{"id":400,"date":"2024-06-30T20:15:09","date_gmt":"2024-06-30T12:15:09","guid":{"rendered":"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/?p=400"},"modified":"2024-07-06T20:52:28","modified_gmt":"2024-07-06T12:52:28","slug":"generative-metaprogramming-chapter5","status":"publish","type":"post","link":"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/","title":{"rendered":"\u300a\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\u300b\u7b2c\u4e94\u7ae0 \u5fc6\u6614\u5e74\u6a21\u677f\u4e09\u4e24\u4e8b"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_85 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\r\n<div class=\"ez-toc-title-container\">\r\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\r\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/http\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/http\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\r\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E5%89%8D%E8%A8%80\" >\u524d\u8a00<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E6%B3%9B%E5%9E%8B%E2%80%A6%E2%80%A6%E5%85%83%E7%BC%96%E7%A8%8B\" >\u6cdb\u578b\u2026\u2026\u5143\u7f16\u7a0b<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E6%8A%BD%E8%B1%A1%E5%8C%96%E3%80%81%E5%85%B7%E4%BD%93%E5%8C%96%E2%80%A6%E2%80%A6%E6%A8%A1%E6%9D%BF\" >\u62bd\u8c61\u5316\u3001\u5177\u4f53\u5316\u2026\u2026\u6a21\u677f<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E5%8F%98%E9%87%8F%E3%80%81%E5%87%BD%E6%95%B0%E4%B8%8E%E7%B1%BB%E6%A8%A1%E6%9D%BF\" >\u53d8\u91cf\u3001\u51fd\u6570\u4e0e\u7c7b\u6a21\u677f<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E5%8F%98%E9%87%8F%E6%A8%A1%E6%9D%BF\" 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class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E6%A8%A1%E6%9D%BF%E5%8F%82%E6%95%B0\" >\u6a21\u677f\u53c2\u6570<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E6%A8%A1%E6%9D%BF%E5%8F%82%E6%95%B0%E7%9A%84%E7%B1%BB%E5%9E%8B\" >\u6a21\u677f\u53c2\u6570\u7684\u7c7b\u578b<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E7%B1%BB%E5%9E%8B%E5%8F%82%E6%95%B0%EF%BC%88Type%EF%BC%89\" 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href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E5%AE%9E%E7%8E%B0_make_index_sequence_%E5%B1%95%E7%8E%B0%E5%87%BA%E7%9A%84%E5%90%84%E7%A7%8D%E6%A8%A1%E6%9D%BF%E6%8A%80%E6%9C%AF\" >\u5b9e\u73b0 make_index_sequence \u5c55\u73b0\u51fa\u7684\u5404\u79cd\u6a21\u677f\u6280\u672f<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E4%BB%A5%E6%A8%A1%E6%9D%BF%E5%81%8F%E7%89%B9%E5%8C%96%E5%AE%9E%E7%8E%B0_make_index_sequence\" >\u4ee5\u6a21\u677f\u504f\u7279\u5316\u5b9e\u73b0 make_index_sequence<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E4%BB%A5_constexpr_if_%E5%AE%9E%E7%8E%B0_make_index_sequence\" >\u4ee5 constexpr if \u5b9e\u73b0 make_index_sequence<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E4%BB%A5%E9%80%92%E5%BD%92_Lambda_%E5%AE%9E%E7%8E%B0_make_index_sequence\" >\u4ee5\u9012\u5f52 Lambda \u5b9e\u73b0 make_index_sequence<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E4%BB%A5%E6%A0%87%E7%AD%BE%E5%88%86%E5%8F%91%E5%AE%9E%E7%8E%B0_make_index_sequence\" >\u4ee5\u6807\u7b7e\u5206\u53d1\u5b9e\u73b0 make_index_sequence<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-19\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E4%B8%80%E7%A7%8D%E6%9B%B4%E5%BF%AB%E7%9A%84_make_index_sequence_%E5%AE%9E%E7%8E%B0%E6%B3%95\" >\u4e00\u79cd\u66f4\u5feb\u7684 make_index_sequence \u5b9e\u73b0\u6cd5<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-20\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E7%B1%BB%E5%9E%8B%E8%90%83%E5%8F%96\" >\u7c7b\u578b\u8403\u53d6<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-21\" href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2024\/06\/30\/generative-metaprogramming-chapter5\/#%E6%80%BB%E7%BB%93\" >\u603b\u7ed3<\/a><\/li><\/ul><\/nav><\/div>\r\n<h2><span class=\"ez-toc-section\" id=\"%E5%89%8D%E8%A8%80\"><\/span>\u524d\u8a00<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u672c\u7cfb\u5217\u5206\u4e3a\u4e0a\u4e2d\u4e0b\u4e09\u4e2a\u7bc7\u7ae0\uff0c\u524d\u56db\u7ae0\u4f5c\u4e3a\u4e0a\u7bc7\uff0c\u8be6\u7ec6\u4ecb\u7ecd\u4e86\u5b8f\u5728\u4ea7\u751f\u5f0f\u7f16\u7a0b\u4e2d\u7684\u539f\u7406\u548c\u5e94\u7528\uff0c\u672c\u7ae0\u5f00\u59cb\u6b65\u5165\u4e2d\u7bc7\uff0c\u6b63\u5f0f\u8fdb\u5165 C++ \u7684\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\u6280\u672f\u3002<\/p>\n<p>\u5b8f\u662f C \u65f6\u671f\u7684\u4ea7\u7269\uff0c\u529f\u80fd\u9887\u4e3a\u7b80\u964b\uff0c\u4ea6\u975e\u56fe\u7075\u5b8c\u5907\uff0c\u5373\u6216\u8bf8\u822c\u5947\u6280\u5999\u8bc0\u52a0\u8eab\uff0c\u9650\u5236\u4ecd\u591a\u3002\u4e14\u8c03\u8bd5\u4e0d\u6613\uff0c\u6709\u6240\u675f\u7f1a\uff0c\u4ee5\u662f\u4ec5\u4f5c\u8f85\u52a9\uff0c\u7528\u6765\u5b9e\u73b0\u7b80\u5355\u7684\u4ee3\u7801\u751f\u6210\u529f\u80fd\u3002\u81f3 C++ \u65f6\u671f\uff0c\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\u5de5\u5177\u9661\u589e\uff0c\u5176\u4e2d\u4ee5\u6a21\u677f\u4e3a\u4e00\u5207\u7684\u6839\u57fa\uff0c\u53d1\u679d\u6563\u53f6\uff0c\u5c14\u4eca\u6b63\u5411\u9759\u6001\u53cd\u5c04\u524d\u8fdb\u3002<\/p>\n<p>\u672c\u7ae0\u6d89\u53ca\u4e0d\u8ba1\u5176\u6570\u7684\u6a21\u677f\u6280\u672f\uff0c\u4e3b\u8981\u96c6\u4e2d\u4e8e\u6a21\u677f\u7684\u6838\u5fc3\u7406\u8bba\u548c\u7528\u6cd5\uff0c\u6982\u5ff5\u9519\u7efc\u590d\u6742\uff0c\u6280\u672f\u5c42\u51fa\u4e0d\u7a77\u3002\u96be\u5ea6\u7b49\u7ea7\u7edd\u5bf9\u4e0d\u4f4e\uff0c\u662f\u672c\u7cfb\u5217\u4e2d\u975e\u5e38\u91cd\u8981\u7684\u4e00\u7ae0\u3002<\/p>\n<p>\u7eb5\u7136\u67d0\u4e9b\u6982\u5ff5\u548c\u6280\u672f\u4f60\u5df2\u77e5\u6089\uff0c\u4e5f\u83ab\u8981\u8df3\u8fc7\u67d0\u4e2a\u5c0f\u8282\uff0c\u56e0\u4e3a\u672c\u7cfb\u5217\u7684\u91cd\u5fc3\u4e0d\u5728\u6a21\u677f\u7f16\u7a0b\uff0c\u800c\u5728\u4ea7\u751f\u5f0f\u7f16\u7a0b\uff0c\u8bba\u8ff0\u89d2\u5ea6\u5c06\u6709\u6240\u5dee\u5f02\u3002<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E6%B3%9B%E5%9E%8B%E2%80%A6%E2%80%A6%E5%85%83%E7%BC%96%E7%A8%8B\"><\/span>\u6cdb\u578b\u2026\u2026\u5143\u7f16\u7a0b<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u4f20\u7edf\u8fc7\u7a0b\u5f0f\u7f16\u7a0b\u7684\u601d\u8def\u662f\u5c06\u903b\u8f91\u4f5c\u4e3a\u51fd\u6570\uff0c\u6570\u636e\u4f5c\u4e3a\u51fd\u6570\u7684\u8f93\u5165\u548c\u8f93\u51fa\uff0c\u901a\u8fc7\u65e0\u6570\u4e2a\u51fd\u6570\u6765\u7ec4\u7ec7\u5b8c\u6574\u7684\u903b\u8f91\u9700\u6c42\uff0c\u597d\u4f3c\u642d\u79ef\u6728\uff0c\u6784\u5efa\u51fa\u5404\u79cd\u7269\u4f53\u3002<\/p>\n<p>\u9762\u5411\u5bf9\u8c61\u7f16\u7a0b\u66f4\u8fdb\u4e00\u6b65\uff0c\u601d\u8def\u662f\u5c06\u903b\u8f91\u548c\u6570\u636e\u5408\u5e76\u8d77\u6765\uff0c\u6784\u6210\u4e00\u4e2a\u4e2a\u7c7b\uff0c\u7c7b\u4e2d\u5305\u542b\u5404\u79cd\u6570\u636e\u548c\u51fd\u6570\uff0c\u5916\u90e8\u53ea\u80fd\u501f\u52a9\u516c\u5f00\u51fd\u6570\u64cd\u7eb5\u8fd9\u4e9b\u6570\u636e\u3002\u8fd9\u79cd\u4ee5\u5bf9\u8c61\u8868\u793a\u73b0\u5b9e\u4e8b\u7269\u7684\u65b9\u5f0f\u4e0e\u4eba\u7684\u601d\u7ef4\u66f4\u52a0\u63a5\u8fd1\uff0c\u7b80\u5316\u4e86\u62bd\u8c61\u5316\u7684\u96be\u5ea6\u3002<\/p>\n<p>\u6cdb\u578b\u7f16\u7a0b\u5219\u6b32\u5c06\u903b\u8f91\u548c\u6570\u636e\u5206\u79bb\uff0c\u5e76\u63d0\u4f9b\u4e00\u79cd\u62bd\u8c61\u5316\u6570\u636e\u7684\u65b9\u5f0f\uff0c\u4f7f\u5f97\u4e0d\u540c\u7684\u6570\u636e\u80fd\u591f\u4f7f\u7528\u540c\u4e00\u79cd\u903b\u8f91\uff0c\u6781\u5927\u964d\u4f4e\u4e86\u4ee3\u7801\u7684\u91cd\u590d\u6027\u3002\u4e8e\u662f\uff0c\u540c\u4e00\u4e2a\u51fd\u6570\u80fd\u591f\u4f20\u9012\u4e0d\u540c\u7684\u53c2\u6570\u7c7b\u578b\uff0c\u8fd9\u53eb\u51fd\u6570\u6a21\u677f\uff1b\u540c\u4e00\u4e2a\u7c7b\u80fd\u591f\u4f20\u9012\u4e0d\u540c\u7684\u6570\u636e\uff0c\u8fd9\u53eb\u7c7b\u6a21\u677f\u3002<\/p>\n<p>C++ \u662f\u4e00\u79cd\u591a\u8303\u5f0f\u8bed\u8a00\uff0c\u4ee5\u6a21\u677f\u652f\u6301\u6cdb\u578b\u7f16\u7a0b\uff0c\u5141\u8bb8\u7f16\u5199\u6cdb\u578b\u7684\u51fd\u6570\u548c\u6570\u636e\uff0c\u529f\u80fd\u4e0d\u4f9d\u8d56\u4e8e\u67d0\u79cd\u5177\u4f53\u7684\u6570\u636e\u7c7b\u578b\uff0c\u4f7f\u7528 SFINAE \u548c Concepts \u7ea6\u675f\u62bd\u8c61\u5316\u7684\u7c7b\u578b\u3002\u8fd9\u79cd\u80fd\u529b\u4f7f\u5176\u652f\u6301 Parametric Polymorphism\uff0c\u5728\u591a\u6001\u7684\u9009\u62e9\u4e0a\u4e0d\u5fc5\u5c40\u9650\u4e8e\u4f20\u7edf\u7684 Subtype Polymorphism\uff0c\u53ef\u4ee5\u4f7f\u7528\u7f16\u8bd1\u671f\u591a\u6001\u66ff\u4ee3\u8fd0\u884c\u671f\u591a\u6001\u3002<\/p>\n<p>C++ \u4e2d\uff0c\u5143\u7f16\u7a0b\u6307\u7684\u662f\u53d1\u751f\u4e8e\u7f16\u8bd1\u671f\u7684\u7f16\u7a0b\uff0c\u6a21\u677f\u4e3a C++ \u5e26\u6765\u6cdb\u578b\u7f16\u7a0b\u7684\u540c\u65f6\uff0c\u4e5f\u5e26\u6765\u4e86\u5143\u7f16\u7a0b\u80fd\u529b\u3002\u7531\u6a21\u677f\u5b9e\u73b0\u7684\u5143\u7f16\u7a0b\uff0c\u79f0\u4e3a\u6a21\u677f\u5143\u7f16\u7a0b\u3002\u800c\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\uff0c\u6307\u7684\u662f\u53d1\u751f\u4e8e\u7f16\u8bd1\u671f\u7684\u5bf9\u4e8e\u7f16\u7a0b\u7684\u7f16\u7a0b\uff0c\u6a21\u677f\u672c\u5c31\u652f\u6301\u5728\u7f16\u8bd1\u671f\u751f\u6210\u4ee3\u7801\uff0c\u56e0\u6b64\u6a21\u677f\u4e5f\u80fd\u591f\u5b9e\u73b0\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\u3002<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E6%8A%BD%E8%B1%A1%E5%8C%96%E3%80%81%E5%85%B7%E4%BD%93%E5%8C%96%E2%80%A6%E2%80%A6%E6%A8%A1%E6%9D%BF\"><\/span>\u62bd\u8c61\u5316\u3001\u5177\u4f53\u5316\u2026\u2026\u6a21\u677f<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u5728\u6a21\u677f\u4e16\u754c\u4e2d\uff0c\u51fd\u6570\u4e0d\u518d\u662f\u5177\u4f53\u7684\u51fd\u6570\uff0c\u6570\u636e\u7c7b\u578b\u4e5f\u4e0d\u518d\u662f\u5177\u4f53\u7684\u6570\u636e\u7c7b\u578b\u3002\u6a21\u677f\u5b9b\u5982\u4e00\u4e2a\u6a21\u5177\uff0c\u501f\u5176\u80fd\u591f\u4ea7\u751f\u5404\u5f0f\u5404\u6837\u7684\u7269\u4f53\uff0c\u8fd9\u4e9b\u7269\u4f53\u7684\u989c\u8272\u3001\u6750\u6599\u53ef\u80fd\u4e0d\u5c3d\u76f8\u540c\uff0c\u4f46\u662f\u5f62\u72b6\u3001\u5927\u5c0f\u662f\u4e00\u81f4\u7684\u3002\u4e5f\u5c31\u662f\u8bf4\uff0c\u4e00\u7c7b\u7269\u4f53\uff0c\u5fc5\u987b\u5b58\u5728\u5171\u540c\u7684\u90e8\u5206\uff0c\u624d\u80fd\u591f\u62bd\u8c61\u51fa\u4e00\u4e2a\u6a21\u5177\uff0c\u6a21\u5177\u7684\u4f5c\u7528\u5c31\u662f\u91cd\u590d\u5229\u7528\u8fd9\u4e9b\u5171\u540c\u4e4b\u5904\uff0c\u51cf\u5c11\u91cd\u590d\u6027\u3002<\/p>\n<p>\u7f16\u7a0b\u662f\u5de5\u5177\uff0c\u672c\u8d28\u662f\u89e3\u51b3\u95ee\u9898\uff0c\u89e3\u51b3\u95ee\u9898\u8003\u9a8c\u7684\u5c31\u662f\u62bd\u8c61\u5316\u548c\u5177\u4f53\u5316\u7684\u80fd\u529b\u3002\u62bd\u8c61\u5316\u5e94\u5bf9\u7684\u662f\u73b0\u5b9e\u4e16\u754c\u4e2d\u7684\u4e0d\u53d8\uff0c\u800c\u5177\u4f53\u5316\u5e94\u5bf9\u7684\u662f\u73b0\u5b9e\u4e16\u754c\u4e2d\u7684\u53d8\u5316\uff0c\u80fd\u591f\u6e05\u695a\u5730\u8ba4\u8bc6\u5230\u53d8\u4e0e\u4e0d\u53d8\u662f\u4ec0\u4e48\uff0c\u95ee\u9898\u4e5f\u5c31\u8fce\u5203\u800c\u89e3\u4e86\u3002\u90a3\u5148\u6765\u5206\u6e05\u62bd\u8c61\u5316\u548c\u5177\u4f53\u5316\u7684\u6982\u5ff5\u3002<\/p>\n<p>\u62bd\u8c61\u7684\u610f\u601d\u662f\uff0c\u5728\u8bb8\u591a\u4e8b\u7269\u4e2d\uff0c\u53bb\u9664\u975e\u672c\u8d28\u7684\u5c5e\u6027\uff0c\u62bd\u51fa\u672c\u8d28\u5c5e\u6027\u3002\u62bd\u8c61\u5316\u5c31\u662f\u5448\u73b0\u51fa\u5177\u4f53\u4e8b\u7269\u5171\u540c\u672c\u8d28\u7684\u8fc7\u7a0b\u3002\u5c06\u590d\u6742\u7684\u73b0\u5b9e\uff0c\u7b80\u5316\u6210\u5355\u7eaf\u7684\u6a21\u578b\uff0c\u8fd9\u79cd\u62bd\u8c61\u5316\u65b9\u5f0f\u79f0\u4e3a\u6a21\u578b\u5316\uff0c\u6240\u8c13\u95ee\u9898\u5efa\u6a21\uff0c\u5c31\u662f\u5bf9\u95ee\u9898\u8fdb\u884c\u6a21\u578b\u5316\uff0c\u4e5f\u5373\u62bd\u8c61\u7684\u8fc7\u7a0b\u3002\u5177\u4f53\u7684\u6982\u5ff5\u76f8\u5bf9\u7b80\u5355\uff0c\u5c31\u662f\u6307\u770b\u5f97\u89c1\u6478\u5f97\u7740\u7684\u4e8b\u7269\uff0c\u6bcf\u4e2a\u4e8b\u7269\u90fd\u662f\u72ec\u4e00\u65e0\u4e8c\u7684\uff0c\u662f\u4ee5\u53d8\u5316\u5c24\u76db\u3002\u5177\u4f53\u5316\u5c31\u662f\u5c06\u62bd\u8c61\u4e8b\u7269\u52a0\u8f7d\u6e05\u6670\u7684\u8fc7\u7a0b\uff0c\u662f\u4e00\u79cd\u6709\u52a9\u4e8e\u7406\u89e3\u964c\u751f\u4e8b\u7269\u7684\u65b9\u5f0f\u3002\u6570\u636e\u7c7b\u578b\u662f\u5177\u4f53\u4e8b\u7269\uff0c\u80fd\u591f\u6e05\u6670\u7b80\u660e\u5730\u5448\u73b0\u51fa\u4e0d\u540c\u6570\u636e\u7c7b\u578b\u7684\u5171\u540c\u903b\u8f91\uff0c\u5c31\u662f\u7528\u6a21\u677f\u7c7b\u578b\u4ee3\u66ff\u5177\u4f53\u7c7b\u578b\u7684\u7cbe\u5999\u4e4b\u5904\u3002<\/p>\n<p>\u6a21\u677f\u672c\u8eab\u662f\u4e00\u79cd\u62bd\u8c61\u5316\u7684\u5de5\u5177\uff0c\u4ee5\u5176\u7f16\u5199\u7684\u662f\u62bd\u8c61\u903b\u8f91\uff0c\u8868\u793a\u67d0\u7c7b\u7c7b\u578b\u7684\u5171\u6709\u672c\u8d28\uff0c\u662f\u4e0d\u53d8\u7684\u90e8\u5206\u3002\u5176\u672c\u8eab\u662f\u6ca1\u6709\u7528\u7684\uff0c\u5b9e\u9645\u9700\u8981\u7684\u8fd8\u662f\u5177\u4f53\u903b\u8f91\uff0c\u56e0\u6b64\u9700\u8981\u6709\u5177\u4f53\u5316\u7684\u8fc7\u7a0b\uff0c\u5c06\u62bd\u8c61\u903b\u8f91\u8f6c\u53d8\u4e3a\u5177\u4f53\u903b\u8f91\u3002\u5728 C++ \u6a21\u677f\u4e2d\uff0c\u8fd9\u79cd\u5c06\u62bd\u8c61\u903b\u8f91\u8f6c\u53d8\u6210\u5177\u4f53\u903b\u8f91\u7684\u8fc7\u7a0b\uff0c\u79f0\u4e3a\u5b9e\u4f8b\u5316\u3002\u5b9e\u4f8b\u5316\u5c06\u5728\u7f16\u8bd1\u671f\u5c06\u62bd\u8c61\u7c7b\u578b\u66ff\u6362\u6210\u5177\u4f53\u7c7b\u578b\uff0c\u6839\u636e\u6a21\u677f\u751f\u6210\u4e00\u4e2a\u4e2a\u5177\u4f53\u903b\u8f91\u3002\u8fd9\u79cd\u5b9e\u4f8b\u5316\u673a\u5236\uff0c\u4fbf\u662f\u6211\u4eec\u6240\u9700\u8981\u7684\u4ee3\u7801\u751f\u6210\u80fd\u529b\u3002<\/p>\n<p>\u4e0e\u5b8f\u4e0d\u540c\uff0c\u6a21\u677f\u5177\u4f53\u5316\u540e\u751f\u6210\u7684\u4ee3\u7801\uff0c\u5e76\u65e0\u6cd5\u76f4\u63a5\u5728\u751f\u6210\u7684\u6e90\u7801\u4e2d\u770b\u5230\uff0c\u4f46\u662f\u53ef\u4ee5\u901a\u8fc7 CppInsight \u8fd9\u7c7b\u5de5\u5177\u5bdf\u770b\u3002<\/p>\n<p>\u6bd4\u5982\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template &lt;typename T&gt;\ninline constexpr T Integer = 42;\n\nint main() {\n    std::cout &lt;&lt; Integer&lt;int&gt; &lt;&lt; Integer&lt;long&gt; &lt;&lt; &quot;\\n&quot;;\n}<\/code><\/pre>\n<p>\u5c06\u5728\u7f16\u8bd1\u671f\u751f\u6210\u4ee5\u4e0b\u4ee3\u7801\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;typename T&gt;\ninline constexpr const T Integer = 42;\n\ntemplate&lt;&gt;\ninline constexpr const int Integer&lt;int&gt; = 42;\ntemplate&lt;&gt;\ninline constexpr const long Integer&lt;long&gt; = 42;<\/code><\/pre>\n<p>\u7531\u6b64\uff0c\u901a\u8fc7\u6a21\u677f\uff0c\u6211\u4eec\u62e5\u6709\u4e86\u751f\u6210\u6570\u636e\u548c\u51fd\u6570\u7684\u80fd\u529b\u3002<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E5%8F%98%E9%87%8F%E3%80%81%E5%87%BD%E6%95%B0%E4%B8%8E%E7%B1%BB%E6%A8%A1%E6%9D%BF\"><\/span>\u53d8\u91cf\u3001\u51fd\u6570\u4e0e\u7c7b\u6a21\u677f<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u5728\u7f16\u7a0b\u8bed\u8a00\u4e2d\uff0c\u80fd\u591f\u64cd\u7eb5\u7684\u6700\u5c0f\u5355\u5143\u65e0\u975e\u5c31\u662f\u6570\u636e\u548c\u51fd\u6570\u8fd9\u4e24\u7c7b\u3002\u6570\u636e\u6784\u6210\u4e86\u53d8\u91cf\u53ca\u51fd\u6570\u7684\u8f93\u5165\u8f93\u51fa\uff0c\u6570\u636e\u548c\u51fd\u6570\u53c8\u7ec4\u6210\u4e86\u7c7b\uff0c\u62bd\u8c61\u5316\u4f5c\u7528\u5176\u4e0a\uff0c\u4fbf\u53ef\u5206\u6210\u53d8\u91cf\u6a21\u677f\u3001\u51fd\u6570\u6a21\u677f\u548c\u7c7b\u6a21\u677f\u3002<\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E5%8F%98%E9%87%8F%E6%A8%A1%E6%9D%BF\"><\/span>\u53d8\u91cf\u6a21\u677f<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u53d8\u91cf\u6a21\u677f\u662f\u9488\u5bf9\u53d8\u91cf\u7684\u62bd\u8c61\u5316\uff0c\u4e0e\u5176\u4ed6\u6a21\u677f\u4e0d\u540c\uff0c\u5b83\u76f4\u5230 C++14 \u624d\u8fdb\u5165\u6807\u51c6\u3002<\/p>\n<p>\u56ff\u4e8e C++98\/03 \u7684\u5c40\u9650\u6027\uff0c\u65e7\u65f6\u65e0\u6cd5\u76f4\u63a5\u5bf9\u53d8\u91cf\u65bd\u52a0\u6a21\u677f\u3002\u4e8e\u662f\uff0c\u4ea7\u751f\u4e86\u4e00\u4e9b\u66ff\u4ee3\u4e4b\u6cd5\uff0c\u4e00\u79cd\u662f\u5728\u7c7b\u6a21\u677f\u4e2d\u4f7f\u7528 <code class=\"\" data-line=\"\">constexpr static<\/code> \u6570\u636e\u6210\u5458\uff0c\u53e6\u4e00\u79cd\u662f\u901a\u8fc7 <code class=\"\" data-line=\"\">constexpr<\/code> \u51fd\u6570\u6a21\u677f\u8fd4\u56de\u5e38\u91cf\u503c\u3002<\/p>\n<p>\u7b2c\u4e00\u79cd\u65b9\u6cd5\u5012\u662f\u7ecf\u5178\uff0c\u6bd4\u5982 <code class=\"\" data-line=\"\">std::numeric_limits<\/code> \u7684\u5b9e\u73b0\u3002<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;typename T&gt;\nstruct numeric_limits {\n    static constexpr bool is_modulo = ...;\n};\n\n\/\/ ...\ntemplate&lt;typename T&gt;\nconstexpr bool numeric_limits&lt;T&gt;::is_modulo;<\/code><\/pre>\n<p>\u8fd9\u79cd\u65b9\u6cd5\u5b58\u5728\u4e24\u4e2a\u7f3a\u70b9\uff0c\u4e00\u662f\u91cd\u590d\u6027\uff0c\u5fc5\u987b\u5728\u7c7b\u5916\u5b9a\u4e49\u9759\u6001\u6570\u636e\u6210\u5458\uff0c\u4ee5\u6ee1\u8db3 ODR-used \u6570\u636e\uff08\u8fd9\u70b9\u5728 C++17 \u4e4b\u540e\u4e0d\u518d\u662f\u95ee\u9898\uff0c\u901a\u8fc7 <code class=\"\" data-line=\"\">inline<\/code> \u53ef\u4ee5\u5149\u660e\u6b63\u5927\u5730\u8fdd\u80cc ODR\uff09\uff1b\u4e8c\u662f\u7b80\u6d01\u6027\uff0c\u4f7f\u7528\u65f6\u9700\u8981\u901a\u8fc7 <code class=\"\" data-line=\"\">numeric_limits&lt;X&gt;::is_modulo<\/code> \u8fd9\u79cd\u5197\u4f59\u7684\u8bed\u6cd5\u5f62\u5f0f\u3002<\/p>\n<p>\u7b2c\u4e8c\u79cd\u65b9\u6cd5\uff0c\u540c\u6837\u53ef\u4ee5\u770b <code class=\"\" data-line=\"\">std::numeric_limits<\/code> \u7684\u5b9e\u73b0\u3002<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;&gt;\nstruct numeric_limits&lt;int&gt;\n{\n    static constexpr int\n    min() noexcept { return -__INT_MAX__ - 1; }\n\n    static constexpr int\n    max() noexcept { return __INT_MAX__; }\n\n    ...\n};<\/code><\/pre>\n<p>\u8fd9\u79cd\u65b9\u6cd5\u4e0d\u5b58\u5728\u7b2c\u4e00\u79cd\u65b9\u6cd5\u5f53\u4e2d\u7684\u91cd\u590d\u6027\u95ee\u9898\uff0c\u4f46\u5728\u5b9a\u4e49\u65f6\u9700\u8981\u63d0\u524d\u9009\u62e9\u5982\u4f55\u4f20\u9012\u5e38\u91cf\u3002\u8981\u4e48\u901a\u8fc7 <code class=\"\" data-line=\"\">const<\/code> \u5f15\u7528\u4f20\u9012\uff0c\u6b64\u65f6\u9700\u8981\u8fd4\u56de\u4e00\u4e2a\u5b58\u50a8\u4e8e\u9759\u6001\u533a\u5e38\u91cf\uff1b\u8981\u4e48\u901a\u8fc7\u503c\u4f20\u9012\uff0c\u6bcf\u6b21\u8fd4\u56de\u65f6\u90fd\u590d\u5236\u4e00\u4efd\u5e38\u91cf\u3002\u76f4\u63a5\u4f7f\u7528 <code class=\"\" data-line=\"\">const(expr)<\/code> \u4e0d\u4f1a\u5b58\u5728\u8fd9\u4e2a\u95ee\u9898\uff0c\u5e38\u91cf\u662f\u5426\u9700\u8981\u5b9e\u9645\u5b58\u50a8\u53ea\u4f9d\u8d56\u4e8e\u4f7f\u7528\u60c5\u5883\uff0c\u800c\u4e0d\u4f9d\u8d56\u4e8e\u5b9a\u4e49\u3002<\/p>\n<p>\u4e8b\u5b9e\u4e0a\uff0c\u7f16\u8bd1\u5668\u7684\u4f18\u5316\u80fd\u529b\u4eca\u975e\u6614\u6bd4\uff0cRVO \u4f18\u5316\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u80fd\u591f\u907f\u514d\u8fd9\u4e9b\u7f3a\u9677\uff0c\u4f46\u6beb\u65e0\u7591\u95ee\uff0c\u53d8\u91cf\u6a21\u677f\u80fd\u591f\u66f4\u76f4\u63a5\u3001\u7b80\u5355\u3001\u9ad8\u6548\u5730\u89e3\u51b3\u95ee\u9898\u3002<\/p>\n<p>\u540e\u671f\u7684\u5b9e\u73b0\u90fd\u4f1a\u907f\u514d\u8fd9\u4e9b\u66ff\u4ee3\u65b9\u6cd5\uff0c\u800c\u662f\u76f4\u63a5\u91c7\u7528\u53d8\u91cf\u6a21\u677f\u6765\u89e3\u51b3\u76f8\u5173\u95ee\u9898\u3002\u4e8e\u662f\uff0c\u53ef\u4ee5\u770b\u5230 <code class=\"\" data-line=\"\">xxx::value<\/code> \u90fd\u88ab <code class=\"\" data-line=\"\">xxx_v<\/code> \u8fdb\u4e00\u6b65\u66ff\u4ee3\uff0cMathematical constants \u4e5f\u6e05\u4e00\u8272\u5730\u4f7f\u7528 <code class=\"\" data-line=\"\">inline constexpr<\/code> \u53d8\u91cf\u6a21\u677f\u3002<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">namespace std::numbers {\n    template&lt;class T&gt; inline constexpr T e_v          = \/* unspecified *\/;\n    template&lt;class T&gt; inline constexpr T log2e_v      = \/* unspecified *\/;\n    template&lt;class T&gt; inline constexpr T log10e_v     = \/* unspecified *\/;\n    template&lt;class T&gt; inline constexpr T pi_v         = \/* unspecified *\/;\n    template&lt;class T&gt; inline constexpr T inv_pi_v     = \/* unspecified *\/;\n    template&lt;class T&gt; inline constexpr T inv_sqrtpi_v = \/* unspecified *\/;\n    template&lt;class T&gt; inline constexpr T ln2_v        = \/* unspecified *\/;\n    template&lt;class T&gt; inline constexpr T ln10_v       = \/* unspecified *\/;\n    template&lt;class T&gt; inline constexpr T sqrt2_v      = \/* unspecified *\/;\n    template&lt;class T&gt; inline constexpr T sqrt3_v      = \/* unspecified *\/;\n    template&lt;class T&gt; inline constexpr T inv_sqrt3_v  = \/* unspecified *\/;\n    template&lt;class T&gt; inline constexpr T egamma_v     = \/* unspecified *\/;\n    template&lt;class T&gt; inline constexpr T phi_v        = \/* unspecified *\/;\n\n    inline constexpr double e          = e_v&lt;double&gt;;\n    inline constexpr double log2e      = log2e_v&lt;double&gt;;\n    inline constexpr double log10e     = log10e_v&lt;double&gt;;\n    inline constexpr double pi         = pi_v&lt;double&gt;;\n    inline constexpr double inv_pi     = inv_pi_v&lt;double&gt;;\n    inline constexpr double inv_sqrtpi = inv_sqrtpi_v&lt;double&gt;;\n    inline constexpr double ln2        = ln2_v&lt;double&gt;;\n    inline constexpr double ln10       = ln10_v&lt;double&gt;;\n    inline constexpr double sqrt2      = sqrt2_v&lt;double&gt;;\n    inline constexpr double sqrt3      = sqrt3_v&lt;double&gt;;\n    inline constexpr double inv_sqrt3  = inv_sqrt3_v&lt;double&gt;;\n    inline constexpr double egamma     = egamma_v&lt;double&gt;;\n    inline constexpr double phi        = phi_v&lt;double&gt;;\n}<\/code><\/pre>\n<p>\u5982\u4eca\uff0c\u82e5\u662f\u60f3\u4f7f\u7528\u5e38\u91cf $$\\pi$$\uff0c\u53ef\u4ee5\u76f4\u63a5\u901a\u8fc7 <code class=\"\" data-line=\"\">std::numbers::pi<\/code> \u5f97\u5230\u9ed8\u8ba4\u7c7b\u578b\u7684\uff0c\u663e\u5f0f\u5730\u4f20\u9012\u6a21\u677f\u53c2\u6570\uff0c\u53ef\u4ee5\u5f97\u5230\u4e0d\u540c\u7c7b\u578b\u7684\u5e38\u91cf\u3002<\/p>\n<p>\u6ce8\u610f\uff0c\u53d8\u91cf\u6a21\u677f\u5e38\u5728 file scope \u4e0b\u4f7f\u7528\uff0c\u6b64\u65f6 <code class=\"\" data-line=\"\">constexpr<\/code> \u4f1a\u9690\u5f0f Internal Linkage\uff0c\u5018\u53ea\u5355\u72ec\u4f7f\u7528 <code class=\"\" data-line=\"\">constexpr<\/code> \u4fee\u9970\u53d8\u91cf\u6a21\u677f\uff0c\u591a\u4e2a TUs \u95f4\u94fe\u63a5\u4f1a\u62f7\u8d1d\u591a\u4efd\u6570\u636e\uff0c\u9020\u6210\u5de8\u5927\u7684\u5f00\u9500\u3002\u800c <code class=\"\" data-line=\"\">inline<\/code> \u80fd\u591f\u6307\u5b9a External Linkage\uff0c\u907f\u514d\u8fd9\u79cd\u5f00\u9500\uff0c\u662f\u4ee5\u53d8\u91cf\u6a21\u677f\u4e00\u822c\u90fd\u91c7\u7528 <code class=\"\" data-line=\"\">inline constexpr<\/code> \u4fee\u9970\u3002<\/p>\n<p>\u8fd9\u4e9b\u90fd\u53ea\u662f\u6807\u51c6\u4e2d\u7684\u4f8b\u5b50\uff0c\u73b0\u5b9e\u4e2d\u6709\u54ea\u4e9b\u7528\u5230\u53d8\u91cf\u6a21\u677f\u7684\u4f8b\u5b50\u5462\uff1f<\/p>\n<p>\u7b2c\u4e00\u4e2a\u4f8b\u5b50\uff0c\u5047\u8bbe\u4f60\u5728\u5f00\u53d1\u67d0\u4e2a\u6a21\u62df\u5668\uff0c\u9700\u8981\u6307\u5b9a\u6a21\u62df\u7684\u5f00\u59cb\u65f6\u95f4\u548c\u7ed3\u675f\u65f6\u95f4\uff0c\u6a21\u62df\u5668\u662f\u5168\u5c40\u53ef\u7528\u7684\uff0c\u5176\u4e2d\u7684\u6240\u6709\u6a21\u62df\u8bbe\u5907\u90fd\u4f1a\u4f7f\u7528\u8be5\u6a21\u62df\u65f6\u95f4\u3002\u6b64\u65f6\u7684\u4e00\u79cd\u505a\u6cd5\u5c31\u662f\u5c06\u65f6\u95f4\u4ee5 <code class=\"\" data-line=\"\">inline constexpr\/constinit<\/code> \u53d8\u91cf\u6a21\u677f\u653e\u5230\u5168\u5c40\u914d\u7f6e\uff0c\u4ece\u800c\u80fd\u591f\u5206\u522b\u6307\u5b9a\u548c\u83b7\u53d6\u4ee5 <code class=\"\" data-line=\"\">milliseconds\/seconds\/minutes\/hours...<\/code> \u4e3a\u7cbe\u5ea6\u7684\u6a21\u62df\u65f6\u95f4\u3002\u5f53\u7136\uff0c\u66f4\u597d\u7684\u505a\u6cd5\u662f\u50cf asio \u90a3\u6837\uff0c\u62bd\u8c61\u51fa\u4e00\u4e2a <code class=\"\" data-line=\"\">sim_context<\/code>\uff0c\u5c06\u6240\u6709\u914d\u7f6e\u5185\u5bb9\u653e\u5230\u8be5\u7c7b\u5f53\u4e2d\uff0c\u4e4b\u540e\u518d\u5c06\u8be5\u4e0a\u4e0b\u6587\u5bf9\u8c61\u4f20\u9012\u5230\u6bcf\u4e2a\u6a21\u62df\u8bbe\u5907\u5f53\u4e2d\uff0c\u4ece\u800c\u907f\u514d\u5168\u5c40\u5bf9\u8c61\u3002<\/p>\n<p>\u7b2c\u4e8c\u4e2a\u4f8b\u5b50\uff0c\u53d8\u91cf\u6a21\u677f\u53ef\u4ee5\u7ed3\u5408 Lambda \u91cd\u8f7d\u4f7f\u7528\u3002\u6cdb\u578b Lambda \u867d\u7136\u5177\u6709\u51fd\u6570\u6a21\u677f\u548c\u7c7b\u6a21\u677f\u7684\u90e8\u5206\u7279\u5f81\uff0c\u4f46\u5b83\u7684\u6570\u636e\u90e8\u5206\u53ea\u80fd\u901a\u8fc7\u6355\u83b7\u53c2\u6570\uff0c\u65e0\u6cd5\u771f\u6b63\u50cf\u7c7b\u90a3\u6837\u4f7f\u7528\u3002\u901a\u8fc7\u7ed3\u5408\u53d8\u91cf\u6a21\u677f\uff0c\u6cdb\u578b Lambda \u5f97\u4ee5\u50cf\u7c7b\u90a3\u6837\u4f20\u9012\u6570\u636e\u7c7b\u578b\u3002\u5177\u4f53\u7684\u4f8b\u5b50\uff0c\u8fd9\u91cc\u5f15\u7528 <a href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/www.cppmore.com\/2022\/01\/16\/generic-lambda\">\u6cdb\u578b Lambda\uff0c\u5982\u6b64\u5f3a\u5927\uff01<\/a> \u4e2d\u5c55\u793a\u7684\u62bd\u8c61\u5de5\u5382\u6cd5\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;class... Ts&gt; struct AbstractAIFactory : Ts... { using Ts::operator()...; };\ntemplate&lt;class... Ts&gt; AbstractAIFactory(Ts...) -&gt; AbstractAIFactory&lt;Ts...&gt;;\n\ntemplate&lt;class T, class U&gt;\nconcept IsAbstractAI = std::same_as&lt;T, U&gt;;\n\ntemplate&lt;class T&gt;\nstatic constexpr auto AIFactory = AbstractAIFactory {\n    []() requires IsAbstractAI&lt;T, Lux&gt; { return new LuxEasy; },\n    []() requires IsAbstractAI&lt;T, Ziggs&gt; { return new ZiggsEasy; },\n    []() requires IsAbstractAI&lt;T, Teemo&gt; { return new TeemoEasy; }\n};\n\nauto lux = AIFactory&lt;Ziggs&gt;();\nlux-&gt;print();<\/code><\/pre>\n<p>\u6b64\u5904 <code class=\"\" data-line=\"\">AIFactory<\/code> \u5e76\u4e0d\u4f4d\u4e8e file scope\uff0c\u4e8e\u662f\u53ef\u4ee5\u4f7f\u7528 <code class=\"\" data-line=\"\">static constexpr<\/code> \u5f3a\u4fdd\u8bc1\u7f16\u8bd1\u671f\u6267\u884c\u3002\u8fd9\u91cc\u7684\u91cd\u590d\u6027\u6a21\u677f\u65e0\u6cd5\u89e3\u51b3\uff0c\u4f46\u662f\u501f\u52a9 GMP \u5e93\u76ee\u524d\u7684\u4ee3\u7801\u751f\u6210\u80fd\u529b\uff0c\u89e3\u51b3\u8d77\u6765\u5374\u662f\u4e0d\u518d\u8bdd\u4e0b\u3002\u53ef\u4ee5\u7b80\u5316\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">#define CONCRETE_AI_FACTORY(x) \\\n    []() requires IsAbstractAI&lt;T, x&gt; { return new GMP_CONCAT(x, Easy); },\n\ntemplate&lt;class T&gt;\nstatic constexpr auto AIFactory = AbstractAIFactory {\n    GMP_FOR_EACH(CONCRETE_AI_FACTORY, Lux, Ziggs, Teemo)\n}<\/code><\/pre>\n<p>\u8fd9\u4e5f\u662f\u7ed3\u5408\u4e0d\u540c\u7c7b\u578b\u4ea7\u751f\u5f0f\u5de5\u5177\u7684\u4e00\u4e2a\u4f8b\u5b50\u3002<\/p>\n<p>\u81f3\u6b64\uff0c\u5173\u4e8e\u53d8\u91cf\u6a21\u677f\u7684\u8ba8\u8bba\u544a\u4e00\u6bb5\u843d\uff0c\u7ee7\u7eed\u6765\u770b\u4e0b\u4e00\u7c7b\u6a21\u677f\u3002<\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E5%87%BD%E6%95%B0%E6%A8%A1%E6%9D%BF\"><\/span>\u51fd\u6570\u6a21\u677f<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u51fd\u6570\u6a21\u677f\u662f\u9488\u5bf9\u51fd\u6570\u7684\u62bd\u8c61\u5316\uff0c\u501f\u6b64\u53ef\u4ea7\u751f\u5177\u6709\u540c\u4e00\u903b\u8f91\u7684\u51fd\u6570\u65cf\uff0cC++98\/03 \u4fbf\u8fdb\u5165\u6807\u51c6\u3002<\/p>\n<p>\u51fd\u6570\u6a21\u677f\u662f\u62bd\u8c61\u5316\u7684\u51fd\u6570\u8868\u8fbe\uff0c\u62bd\u8c61\u4e4b\u7269\u672c\u8eab\u5e76\u4e0d\u5b58\u5728\uff0c\u5b83\u65e2\u4e0d\u662f\u7c7b\u578b\uff0c\u4e5f\u4e0d\u662f\u51fd\u6570\u3002\u5177\u4f53\u5316\u4e4b\u540e\u7684\u4ee3\u7801\u624d\u62e5\u6709\u5b9e\u4f53\uff0c\u5177\u6709\u771f\u6b63\u7684\u53c2\u6570\u7c7b\u578b\uff0c\u624d\u5c5e\u4e8e\u51fd\u6570\u3002\u751f\u6210\u53ef\u7528\u4ee3\u7801\u7684\u8fc7\u7a0b\uff0c\u79f0\u4e3a\u51fd\u6570\u6a21\u677f\u5b9e\u4f8b\u5316\uff0c\u5b9e\u4f8b\u5316\u540e\u751f\u6210\u7684\u51fd\u6570\u79f0\u4e3a\u6a21\u677f\u51fd\u6570\u3002<\/p>\n<p>\u51fd\u6570\u6a21\u677f\u5141\u8bb8\u7f16\u5199\u6cdb\u578b\u51fd\u6570\uff0c\u6bd4\u5982\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;class T&gt;\nconst T&amp; min(const T&amp; a, const T&amp; b) {\n    return b &lt; a ? b : a;\n}\n\ntemplate&lt;class T&gt;\nconst T&amp; max(const T&amp; a, const T&amp; b) {\n    return b &lt; a ? a : b;\n}<\/code><\/pre>\n<p><code class=\"\" data-line=\"\">min()<\/code> \u548c <code class=\"\" data-line=\"\">max()<\/code> \u53ef\u4ee5\u63a5\u53d7\u652f\u6301 <code class=\"\" data-line=\"\">operator&lt;<\/code> \u7684\u64cd\u4f5c\u6570\uff0c\u5982\u6b64\u4fbf\u62bd\u8c61\u4e86\u6240\u6709\u7c7b\u578b\u7684\u6700\u5927\u6700\u5c0f\u903b\u8f91\uff0c\u65e0\u9700\u4e3a\u6bcf\u4e2a\u7c7b\u578b\u91cd\u590d\u7f16\u5199\u76f8\u540c\u7684\u529f\u80fd\u3002<\/p>\n<p>\u6ce8\u610f\uff0c\u8fd9\u91cc <code class=\"\" data-line=\"\">max()<\/code> \u7684\u5b9e\u73b0\u4e0e\u6807\u51c6\u7684\u5b9e\u73b0\u4e0d\u540c\uff0c\u6807\u51c6\u91c7\u7528\u7684\u662f <code class=\"\" data-line=\"\">a &lt; b ? b : a<\/code>\u3002\u5728\u4e24\u4e2a\u64cd\u4f5c\u6570\u7b49\u4ef7\u5374\u4e0d\u76f8\u7b49\u65f6\uff0c\u6807\u51c6\u5b9e\u73b0\u5c06\u8fd4\u56de <code class=\"\" data-line=\"\">a<\/code>\uff0c\u800c\u6b64\u5904\u7684\u5b9e\u73b0\u5c06\u8fd4\u56de <code class=\"\" data-line=\"\">b<\/code>\u3002\u91c7\u53d6\u8fd9\u79cd\u5b9e\u73b0\u7684\u76ee\u7684\u662f\u4fdd\u8bc1\u66f4\u5f3a\u7684\u4e00\u81f4\u6027\uff0c\u4f8b\u5982 <code class=\"\" data-line=\"\">{min(a, b), max(a, b)}<\/code>\uff0c\u5728<code class=\"\" data-line=\"\">a<\/code> \u548c <code class=\"\" data-line=\"\">b<\/code> \u7b49\u4ef7\u800c\u4e0d\u76f8\u7b49\u65f6\uff0c\u6807\u51c6\u5b9e\u73b0\u5c06\u8fd4\u56de <code class=\"\" data-line=\"\">{a, a}<\/code>\uff0c\u6b64\u5904\u5b9e\u73b0\u5c06\u8fd4\u56de <code class=\"\" data-line=\"\">{a, b}<\/code>\uff0c\u4e00\u4e2a\u7f6e\u5c0f\uff0c\u53e6\u4e00\u4e2a\u4fbf\u7f6e\u5927\uff0c\u66f4\u52a0\u5229\u4e8e\u6392\u5e8f\u3002<\/p>\n<p>C++ \u4e2d\u7b49\u4ef7\u7684\u5b9a\u4e49\u662f <code class=\"\" data-line=\"\">!(a &lt; b) &amp;&amp; !(b &lt; a)<\/code>\uff0c\u800c\u76f8\u7b49\u7684\u5b9a\u4e49\u662f <code class=\"\" data-line=\"\">a == b<\/code>\uff0c\u524d\u8005\u53ea\u5bf9\u6bd4\u90e8\u5206 values\uff0c\u800c \u540e\u8005\u5bf9\u6bd4\u5168\u90e8 values \u548c types\u3002\u4e0b\u9762\u662f\u4e00\u4e2a\u5b8c\u6574\u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ Check if the two operands are equivalent.\ntemplate&lt;class T&gt;\nconstexpr bool equivalent(T const&amp; a, T const&amp; b) {\n    return !(a &lt; b) &amp;&amp; !(b &lt; a);\n}\n\n\/\/ Check if the two operands are equal.\ntemplate&lt;class T&gt;\nconstexpr bool equal(const T&amp; a, const T&amp; b) {\n    return a == b;\n}\n\n\/\/ max() in standard\ntemplate&lt;class T&gt;\nconstexpr const T&amp; max1(T const&amp; a, T const&amp; b) {\n    return a &lt; b ? b : a;\n}\n\n\/\/ max() in example\ntemplate&lt;class T&gt;\nconstexpr const T&amp; max2(T const&amp; a, T const&amp; b) {\n    return b &lt; a ? a : b;\n}\n\nstruct X { int a, b; };\nconstexpr bool operator==(X const&amp; lhs, X const&amp; rhs) {\n    return lhs.a == rhs.a &amp;&amp; lhs.b == rhs.b;\n}\n\nconstexpr bool operator&lt;(X const&amp; lhs, X const&amp; rhs) {\n    return lhs.a &lt; rhs.a;\n}\n\nint main() {\n    constexpr X x1{0, 1};\n    constexpr X x2{0, 2};\n\n    static_assert(!equal(x1, x2), &quot;x1 and x2 are equal!&quot;);\n    static_assert(equivalent(x1, x2), &quot;x1 and x2 are not equivalent!&quot;);\n\n    static_assert(x1 == max1(x1, x2), &quot;x1 was not returned by max1&quot;);\n    static_assert(x2 == max2(x1, x2), &quot;x2 was not returned by max2&quot;);\n}<\/code><\/pre>\n<p>\u51fd\u6570\u6a21\u677f\u4ea6\u53ef\u91cd\u8f7d\uff0c\u4e0d\u8fc7\u5728\u91cd\u8f7d\u51b3\u8bae\u4e2d\u975e\u6a21\u677f\u51fd\u6570\u8981\u4f18\u4e8e\u6a21\u677f\u51fd\u6570\uff0c\u6b64\u7c7b\u8bdd\u9898\uff0c\u4e0d\u518d\u7ec6\u8ff0\uff0c\u89c1 <a href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/github.com\/lkimuk\/the-book-of-modern-cpp\">[The Book of Modern C++]\/p63<\/a>\u3002<\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E7%B1%BB%E6%A8%A1%E6%9D%BF\"><\/span>\u7c7b\u6a21\u677f<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u7c7b\u6a21\u677f\u662f\u9488\u5bf9\u7c7b\u7684\u62bd\u8c61\u5316\uff0c\u501f\u6b64\u53ef\u4ea7\u751f\u4e0d\u540c\u7c7b\u578b\u7684\u6570\u636e\u548c\u51fd\u6570\uff0c\u652f\u6301\u504f\u7279\u5316\uff0c\u7528\u5904\u6700\u5e7f\u3002C++98 \u5373\u5b58\u5728\uff0c\u81f3 C++03 \u5404\u7c7b\u5947\u6280\u6deb\u5de7\u5df2\u904d\u5730\u751f\u82b1\uff0c\u6781\u4e00\u65f6\u4e4b\u76db\uff0c\u5567\u5567\u4e4b\u58f0\u4e0d\u7edd\u3002<\/p>\n<p>\u7c7b\u6a21\u677f\u4e0e\u524d\u4e24\u7c7b\u6a21\u677f\u6700\u5927\u7684\u4e0d\u540c\u5728\u4e8e\u7c7b\u80fd\u591f\u7ee7\u627f\uff0c\u8fd9\u5176\u4e2d\u6700\u7edd\u5999\u7684\u6280\u672f\u662f\u9012\u5f52\u7ee7\u627f\u3002\u6700\u7ecf\u5178\u7684\u5e94\u7528\u662f <code class=\"\" data-line=\"\">std::tuple<\/code> \u7684\u5b9e\u73b0\uff0c\u4e0b\u9762\u5c55\u793a\u7cbe\u7b80\u7248\u7684\u4e00\u79cd\u5b9e\u73b0\u3002<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;typename... Types&gt; class Tuple;\ntemplate&lt;&gt; class Tuple&lt;&gt; {}\n\ntemplate&lt;typename Head, typename... Tail&gt;\nclass Tuple&lt;Head, Tail...&gt; : public Tuple&lt;Tail...&gt;\n{\n    using TailType = Tuple&lt;Tail...&gt;;\nprotected:\n    Head head_;\n\npublic:\n    Tuple() {}\n    Tuple(Head v, Tail... vtails) : head_(v), TailType(vtails...) {}\n\n    Head head() { return head_; }\n    TailType&amp; tail() { return *this; }\n};<\/code><\/pre>\n<p>\u9012\u5f52\u7ee7\u627f\u5c06\u4f9d\u6b21\u7ee7\u627f\u53ef\u53d8\u6a21\u677f\u53c2\u6570\uff0c\u76f4\u81f3 <code class=\"\" data-line=\"\">Tuple&lt;&gt;<\/code>\uff0c\u5047\u5982\u8c03\u7528\u4e3a <code class=\"\" data-line=\"\">Tuplet(1, 2.0, &quot;blah blah...&quot;)<\/code>\uff0c\u5c55\u5f00\u540e\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">------------------------------\nTuple&lt;&gt;                      |\n------------------------------\n\u2191\n------------------------------\nTuple&lt;string&gt;                |\nstring head_(&quot;blah blah...&quot;);|\n------------------------------\n\u2191\n------------------------------\nTuple&lt;float, string&gt;         |\nfloat head_(2.0);            |\n------------------------------\n\u2191\n------------------------------\nTuple&lt;int, float, string&gt;    |\nint head_(1);                |\n------------------------------<\/code><\/pre>\n<p>\u9012\u5f52\u7ee7\u627f\u662f\u6a21\u677f\u5f53\u4e2d\u6700\u5f3a\u7684\u4ee3\u7801\u751f\u6210\u6280\u672f\uff0c\u5be5\u5be5\u6570\u884c\u5b9e\u73b0\uff0c\u4fbf\u80fd\u81ea\u52a8\u4ea7\u751f\u6210\u5343\u4e0a\u4e07\u884c\u4ee3\u7801\u3002\u76f8\u5e94\u5730\uff0c\u8fd9\u90e8\u5206\u8fd0\u7528\u8d77\u6765\u6781\u4e3a\u590d\u6742\u3002<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E6%B4%9E%E6%82%89%E6%A8%A1%E6%9D%BF%E5%AE%9E%E4%BE%8B%E5%8C%96\"><\/span>\u6d1e\u6089\u6a21\u677f\u5b9e\u4f8b\u5316<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u6a21\u677f\u5b9e\u4f8b\u5316\u7684\u5f62\u5f0f\u5206\u4e3a\u4e24\u79cd\uff0c\u4e00\u79cd\u79f0\u4e3a\u663e\u5f0f\u5b9e\u4f8b\u5316\uff0c\u4e00\u79cd\u79f0\u4e3a\u9690\u5f0f\u5b9e\u4f8b\u5316\u3002\u6a21\u677f\u5b9e\u4f8b\u5316\u7684\u53d8\u91cf\u3001\u51fd\u6570\u548c\u7c7b\u7b49\u5b9e\u4f53\u53eb\u4f5c\u7279\u5316\u3002<\/p>\n<p>\u663e\u5f0f\u5b9e\u4f8b\u5316\u8bed\u6cd5\u5177\u6709\u4e24\u79cd\u5f62\u5f0f\uff0c\u663e\u5f0f\u5b9e\u4f8b\u5316\u5b9a\u4e49\u548c\u663e\u5f0f\u5b9e\u4f8b\u5316\u58f0\u660e\uff0c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<pre><code class=\"\" data-line=\"\">template declaration        \/\/ explicit instantiation definition\nextern template declaration \/\/ explicit instantiation declaration<\/code><\/pre>\n<p>\u663e\u5f0f\u5b9e\u4f8b\u5316\u4e0d\u80fd\u6dfb\u52a0 <code class=\"\" data-line=\"\">inline\/constexpr\/consteval<\/code> \u4fee\u9970\u7b26\uff0c\u4e5f\u4e0d\u80fd\u6dfb\u52a0\u5c5e\u6027\u4fee\u9970\u3002<\/p>\n<p>\u5bf9\u4e8e\u8f83\u5c11\u63a5\u89e6\u6a21\u677f\u7684 C++ \u5f00\u53d1\u8005\u6765\u8bf4\uff0c\u53ef\u80fd\u4ece\u672a\u4f7f\u7528\u8fc7\u663e\u5f0f\u5b9e\u4f8b\u5316\u3002\u4f46\u5bf9\u4e8e\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\u6765\u8bf4\uff0c\u6a21\u677f\u8fd0\u7528\u9891\u7387\u6781\u9ad8\uff0c\u8fd9\u65e0\u7591\u4f1a\u589e\u52a0\u7f16\u8bd1\u65f6\u95f4\u548c\u8f93\u51fa\u5927\u5c0f\uff0c\u800c\u663e\u5f0f\u5b9e\u4f8b\u5316\u80fd\u591f\u4f18\u5316\u8fd9\u65b9\u9762\u7684\u5f00\u9500\u3002<\/p>\n<p>\u82e5\u8981\u6df1\u5165\u8ba8\u8bba\u8fd9\u90e8\u5206\u5185\u5bb9\uff0c\u9700\u8981\u5148\u7406\u89e3\u9690\u5f0f\u5b9e\u4f8b\u5316\uff0c\u5426\u5219\u96be\u4ee5\u77e5\u6653\u5f00\u9500\u4ece\u4f55\u800c\u6765\u3002<\/p>\n<p>\u9690\u5f0f\u5b9e\u4f8b\u5316\u5c31\u662f\u7f16\u8bd1\u5668\u5c06\u62bd\u8c61\u6a21\u677f\u8f6c\u6362\u6210\u5177\u4f53\u4ee3\u7801\u7684\u65b9\u5f0f\uff0c\u7f16\u8bd1\u5668\u548c\u94fe\u63a5\u5668\u5fc5\u987b\u786e\u4fdd\u6bcf\u4e2a\u6a21\u677f\u5b9e\u4f8b\u5728\u53ef\u6267\u884c\u7a0b\u5e8f\u4e2d\u53ea\u4f1a\u5b58\u5728\u4e00\u4efd\u3002C++ \u6807\u51c6\u5e76\u6ca1\u6709\u89c4\u5b9a\u5230\u5e95\u5e94\u8be5\u91c7\u7528\u54ea\u79cd\u65b9\u5f0f\u5b9e\u73b0\uff0c\u4e8b\u5b9e\u4e0a\uff0c\u4e3b\u8981\u5b58\u5728\u4e24\u79cd\u57fa\u672c\u7684\u89e3\u51b3\u65b9\u6848\uff0c\u5206\u522b\u662f Borland \u6a21\u578b\u548c Cfront \u6a21\u578b\u3002<\/p>\n<p>Borland \u6a21\u578b\u4e2d\uff0c\u7f16\u8bd1\u5668\u5728\u6bcf\u4e2a\u4f7f\u7528\u6a21\u677f\u7684\u7ffb\u8bd1\u5355\u5143\u4e2d\u90fd\u4f1a\u751f\u6210\u6a21\u677f\u5b9e\u4f8b\uff0c\u518d\u7531\u94fe\u63a5\u5668\u5c06\u591a\u4e2a\u7ffb\u8bd1\u5355\u5143\u5408\u5e76\u8d77\u6765\uff0c\u5254\u9664\u91cd\u590d\u751f\u6210\u7684\u6a21\u677f\u5b9e\u4f8b\uff0c\u53ea\u4fdd\u7559\u4e00\u4efd\u3002\u6b64\u6a21\u677f\u53ea\u9700\u8003\u8651\u76ee\u6807\u6587\u4ef6\u672c\u8eab\uff0c\u65e0\u9700\u62c5\u5fc3\u5916\u90e8\u590d\u6742\u6027\u3002\u4f46\u662f\uff0c\u7531\u4e8e\u91cd\u590d\u751f\u6210\u591a\u4e2a\u6a21\u677f\u5b9e\u4f8b\uff0c\u6a21\u677f\u4ee3\u7801\u88ab\u91cd\u590d\u7f16\u8bd1\uff0c\u5bfc\u81f4\u7f16\u8bd1\u65f6\u95f4\u589e\u957f\u3002\u8fd9\u79cd\u6a21\u578b\u4e0b\uff0c\u6a21\u677f\u4ee3\u7801\u7684\u5b9a\u4e49\u901a\u5e38\u9700\u8981\u653e\u5728\u5934\u6587\u4ef6\u5f53\u4e2d\uff0c\u4ee5\u5728\u5b9e\u4f8b\u5316\u65f6\u80fd\u88ab\u627e\u5230\u3002<\/p>\n<p>Cfront \u6a21\u578b\u4e2d\uff0c\u589e\u52a0\u4e86\u4e00\u4e2a\u6a21\u677f\u5e93\u7684\u6982\u5ff5\uff0c\u7528\u6765\u81ea\u52a8\u7ef4\u62a4\u6a21\u677f\u5b9e\u4f8b\u3002\u5f53\u6784\u5efa\u5355\u4e2a\u76ee\u6807\u6587\u4ef6\u65f6\uff0c\u7f16\u8bd1\u5668\u4f1a\u5c06\u9047\u5230\u7684\u6a21\u677f\u5b9a\u4e49\u548c\u5b9e\u4f8b\u5316\u653e\u5165\u6a21\u677f\u5e93\uff0c\u5982\u679c\u5b9e\u4f8b\u5316\u5df2\u7ecf\u5b58\u5728\u4e8e\u6a21\u677f\u5e93\u4e2d\uff0c\u7f16\u8bd1\u5668\u4f1a\u91cd\u7528\u8be5\u5b9e\u4f8b\u5316\uff0c\u800c\u4e0d\u662f\u91cd\u65b0\u751f\u6210\u3002\u5728\u94fe\u63a5\u65f6\uff0c\u94fe\u63a5\u5305\u88c5\u5668\u4f1a\u6dfb\u52a0\u6a21\u677f\u5e93\u4e2d\u7684\u5bf9\u8c61\uff0c\u5e76\u7f16\u8bd1\u4efb\u4f55\u4e4b\u524d\u672a\u751f\u6210\u7684\u6240\u9700\u5b9e\u4f8b\u3002\u8fd9\u4e2a\u6a21\u578b\u5bf9\u7f16\u8bd1\u901f\u5ea6\u7684\u4f18\u5316\u7a0b\u5ea6\u66f4\u9ad8\uff0c\u5e76\u4e14\u65e0\u9700\u50cf Borland \u6a21\u578b\u90a3\u6837\u9700\u8981\u66ff\u6362\u94fe\u63a5\u5668\uff0c\u76f4\u63a5\u4f7f\u7528\u7cfb\u7edf\u94fe\u63a5\u5668\u5373\u53ef\u3002\u4f46\u662f\uff0c\u590d\u6742\u6027\u4e5f\u6025\u5267\u589e\u52a0\uff0c\u51fa\u9519\u7684\u6982\u7387\u66f4\u5927\u3002\u5b9e\u8df5\u4e2d\uff0c\u5728\u4e00\u4e2a\u76ee\u5f55\u4e2d\u6784\u5efa\u591a\u4e2a\u7a0b\u5e8f\u548c\u5728\u591a\u4e2a\u76ee\u5f55\u4e2d\u6784\u5efa\u4e00\u4e2a\u7a0b\u5e8f\u53ef\u80fd\u4f1a\u975e\u5e38\u56f0\u96be\u3002\u8fd9\u79cd\u6a21\u578b\u4e0b\uff0c\u4ee3\u7801\u901a\u5e38\u4f1a\u5c06\u975e\u5185\u8054\u6210\u5458\u6a21\u677f\u7684\u5b9a\u4e49\u5206\u79bb\u51fa\u6765\uff0c\u653e\u5230\u4e00\u4e2a\u6587\u4ef6\u4e2d\u5355\u72ec\u7f16\u8bd1\u3002<\/p>\n<p>GNU C++ \u91c7\u7528\u7684\u4fbf\u662f Borland \u6a21\u578b\uff0c\u5728\u7f16\u8bd1\u6a21\u677f\u4ee3\u7801\u65f6\uff0c\u6bcf\u4e2a\u7ffb\u8bd1\u5355\u5143\u4e2d\u90fd\u4f1a\u751f\u6210\u4e00\u4efd\u4f7f\u7528\u7684\u6a21\u677f\u5b9e\u4f8b\uff0c\u968f\u540e\u518d\u7531\u94fe\u63a5\u5668\u79fb\u9664\u91cd\u590d\u751f\u6210\u7684\u5b9e\u4f8b\uff0c\u8fd9\u4fbf\u662f\u5bfc\u81f4\u7f16\u8bd1\u65f6\u95f4\u548c\u8f93\u51fa\u5927\u5c0f\u589e\u52a0\u7684\u7f6a\u9b41\u7978\u9996\u3002<\/p>\n<p>\u5982\u4f55\u5e72\u6389\u8fd9\u4e2a\u7f6a\u9b41\u7978\u9996\uff1f<\/p>\n<p>\u8fd9\u91cc\u4e0d\u8c08\u67d0\u4e2a\u7f16\u8bd1\u5668\u7279\u6709\u7684\u89e3\u51b3\u65b9\u5f0f\uff0c\u53ea\u8bf4 C++ \u6807\u51c6\u6240\u63d0\u4f9b\u7684\u901a\u7528\u65b9\u5f0f\uff0c\u5373\u672c\u8282\u5f00\u5934\u6240\u8bf4\u7684\u663e\u5f0f\u5b9e\u4f8b\u5316\u3002<\/p>\n<p>\u663e\u5f0f\u5b9e\u4f8b\u5316\u5b9a\u4e49 C++03 \u5c31\u5df2\u652f\u6301\uff0c\u4e3b\u8981\u662f\u7528\u6765\u5f3a\u5236\u7f16\u8bd1\u5668\u751f\u6210\u5b9e\u4f8b\u5316\u6a21\u677f\uff1b\u663e\u5f0f\u5b9e\u4f8b\u5316\u58f0\u660e\u4e8e C++11 \u52a0\u5165\u6807\u51c6\uff0c\u4e3b\u8981\u662f\u7528\u6765\u7981\u6b62\u7f16\u8bd1\u5668\u5728\u7ffb\u8bd1\u5355\u5143\u4e2d\u5b9e\u4f8b\u5316\u6a21\u677f\u3002\u6362\u8a00\u4e4b\uff0c\u540e\u8005\u80fd\u591f\u963b\u6b62\u9690\u5f0f\u5b9e\u4f8b\u5316\u3002\u963b\u6b62\u4e4b\u540e\u4fbf\u907f\u514d\u4e86 Borland \u6a21\u578b\u5e26\u6765\u7684\u7f16\u8bd1\u5f00\u9500\uff0c\u51cf\u5c11\u7f16\u8bd1\u65f6\u95f4\uff0c\u90a3\u5982\u4f55\u518d\u4f7f\u7528\u6a21\u677f\u5b9e\u4f8b\u5316\u5462\uff1f\u5c31\u662f\u901a\u8fc7\u663e\u5f0f\u5b9e\u4f8b\u5316\u5b9a\u4e49\uff0c\u624b\u52a8\u5f3a\u5236\u7f16\u8bd1\u5668\u751f\u6210\u3002<\/p>\n<p>\u53e3\u8bf4\u65e0\u51ed\uff0c\u6211\u4eec\u5148\u6765\u9a8c\u8bc1\u4e00\u4e0b\u7f16\u8bd1\u5668\u662f\u5426\u771f\u7684\u4f1a\u751f\u6210\u591a\u4e2a\u6a21\u677f\u5b9e\u4f8b\u3002<\/p>\n<p>\u5148\u51c6\u5907\u6a21\u677f\u5934\u6587\u4ef6 <code class=\"\" data-line=\"\">foo.h<\/code>\uff0c\u5185\u5bb9\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ foo.h\n#ifndef FOO_H_\n#define FOO_H_\n\n#include &lt;iostream&gt;\n\ntemplate&lt;class T&gt;\nclass Foo {\npublic:\n    Foo(T x) : data_(x) {}\n\n    void print() const {\n        std::cout &lt;&lt; &quot;x:&quot; &lt;&lt; data_ &lt;&lt; &quot;\\n&quot;;\n    }\n\nprivate:\n    T data_;\n};\n\n#endif \/\/ FOO_H_<\/code><\/pre>\n<p>\u518d\u51c6\u5907\u4e24\u4e2a\u6e90\u6587\u4ef6\uff0c\u518d\u5176\u4e2d\u4f7f\u7528\u8be5\u6a21\u677f\u5b9a\u4e49\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ source_one.cpp\n#include &quot;foo.h&quot;\n\nvoid do_something1() {\n    Foo&lt;int&gt; foo(1);\n    foo.print();\n}\n\n\/\/ source_two.cpp\n#include &quot;foo.h&quot;\n\nvoid do_something2() {\n    Foo&lt;int&gt; foo(2);\n    foo.print();\n}<\/code><\/pre>\n<p>\u5206\u522b\u4f7f\u7528\u5982\u4e0b\u547d\u4ee4\uff0c\u67e5\u770b\u4e24\u4e2a\u7ffb\u8bd1\u5355\u5143\u7684\u7b26\u53f7\u8868\uff1a<\/p>\n<pre><code class=\"\" data-line=\"\">nm -C -S source_one.o | grep Foo\nnm -C -S source_two.o | grep Foo<\/code><\/pre>\n<p>\u7b26\u53f7\u8868\u4e2d\u7684\u5185\u5bb9\u5206\u522b\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ source_one.o\n0000000000000000 000000000000001b W Foo&lt;int&gt;::Foo(int)\n0000000000000000 000000000000001b W Foo&lt;int&gt;::Foo(int)\n0000000000000000 n Foo&lt;int&gt;::Foo(int)\n0000000000000000 0000000000000048 W Foo&lt;int&gt;::print() const\n\n\/\/ source_two.o\n0000000000000000 000000000000001b W Foo&lt;int&gt;::Foo(int)\n0000000000000000 000000000000001b W Foo&lt;int&gt;::Foo(int)\n0000000000000000 n Foo&lt;int&gt;::Foo(int)\n0000000000000000 0000000000000048 W Foo&lt;int&gt;::print() const<\/code><\/pre>\n<p>\u7b2c\u4e00\u5217\u8868\u793a\u7b26\u53f7\u5728\u76ee\u6807\u6587\u4ef6\u4e2d\u7684\u5730\u5740\uff0c<code class=\"\" data-line=\"\">0000000000000000<\/code> \u8868\u793a\u7f16\u8bd1\u5668\u5728\u7f16\u8bd1\u9636\u6bb5\u6ca1\u6709\u4e3a\u5b83\u4eec\u5206\u914d\u5b9e\u9645\u5730\u5740\uff0c\u8fd9\u4e9b\u5730\u5740\u5c06\u5728\u94fe\u63a5\u9636\u6bb5\u7531\u94fe\u63a5\u5668\u8fdb\u884c\u5206\u914d\u548c\u5904\u7406\uff1b\u7b2c\u4e8c\u5217\u8868\u793a\u751f\u6210\u4ee3\u7801\u7684\u5927\u5c0f\uff1b\u7b2c\u4e09\u5217\u8868\u793a\u7b26\u53f7\u7c7b\u578b\uff0c<code class=\"\" data-line=\"\">W<\/code> \u8868\u793a\u5f31\u7b26\u53f7\uff0c\u5f31\u7b26\u53f7\u5141\u8bb8\u591a\u4e2a\u5b9a\u4e49\u5728\u94fe\u63a5\u65f6\u5171\u5b58\uff0c<code class=\"\" data-line=\"\">n<\/code> \u8868\u793a\u5c40\u90e8\u7b26\u53f7\uff0c\u662f\u7f16\u8bd1\u5668\u751f\u6210\u4f9b\u5185\u90e8\u4f7f\u7528\u7684\u7b26\u53f7\uff0c\u4e0d\u4f1a\u88ab\u5bfc\u51fa\u5230\u6700\u7ec8\u7684\u94fe\u63a5\u9636\u6bb5\uff1b\u6700\u540e\u4e00\u5217\u5c31\u662f\u7b26\u53f7\u7684\u540d\u79f0\u3002<\/p>\n<p>\u540c\u4e00\u4e2a\u5bf9\u8c61\u6587\u4ef6\u4e2d\u51fa\u73b0\u4e86\u76f8\u540c\u7684\u6784\u9020\u51fd\u6570\u7b26\u53f7\uff0c\u8fd9\u662f\u4e3a\u4ec0\u4e48\u5462\uff1f\u76f4\u63a5\u8f93\u51fa Mangled Name \u67e5\u770b\u4e00\u4e0b\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">0000000000000000 W _ZN3FooIiEC1Ei\n0000000000000000 W _ZN3FooIiEC2Ei\n0000000000000000 n _ZN3FooIiEC5Ei\n0000000000000000 W _ZNK3FooIiE5printEv<\/code><\/pre>\n<p>\u53ef\u89c1\uff0c\u5c3d\u7ba1 Demangled Name \u662f\u76f8\u540c\u7684\uff0c\u4f46 Mangled Name \u5374\u4e0d\u76f8\u540c\u3002\u552f\u4e00\u7684\u533a\u522b\u5728\u4e8e <code class=\"\" data-line=\"\">C1\/C2<\/code>\uff0c\u5176\u610f\u4e49\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">&lt;ctor-dtor-name&gt; ::= C1   # complete object constructor\n        ::= C2           # base object constructor\n        ::= C3           # complete object allocating constructor\n        ::= D0           # deleting destructor\n        ::= D1           # complete object destructor\n        ::= D2           # base object destructor<\/code><\/pre>\n<p><code class=\"\" data-line=\"\">C2<\/code> \u8868\u793a\u57fa\u7c7b\u5bf9\u8c61\u6784\u9020\uff0c\u4f8b\u5b50\u4e2d\u5e76\u4e0d\u6d89\u53ca\u7ee7\u627f\uff0c\u4e0d\u9700\u8981\u751f\u6210\u8fd9\u4e2a\u7b26\u53f7\uff0c\u4f46\u7f16\u8bd1\u5668\u4f9d\u7136\u751f\u6210\u4e86\u3002<a href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/http\/gcc.gnu.org\/bugs\/#known\">GCC Bugs<\/a> \u4e2d\u63d0\u53ca\uff0c\u5c3d\u7ba1\u8be5\u95ee\u9898\u9891\u7e41\u88ab\u62a5\u544a\uff0c\u4f46\u5e76\u4e0d\u662f\u5b9e\u9645\u7684\u9519\u8bef\uff1a<\/p>\n<blockquote>\n<p>G++ emits two copies of constructors and destructors.<br \/>\n&nbsp;&nbsp;&nbsp;&nbsp;In general there are three types of constructors (and destructors).<\/p>\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;1. The complete object constructor\/destructor.<br \/>\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2. The base object constructor\/destructor.<br \/>\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3. The allocating constructor\/deallocating destructor.<br \/>\n&nbsp;&nbsp;&nbsp;&nbsp;The first two are different, when virtual base classes are involved.<\/p>\n<\/blockquote>\n<p>\u4f8b\u5b50\u4e2d\u6ca1\u6709\u865a\u57fa\u7c7b\uff0c<code class=\"\" data-line=\"\">C1\/C2<\/code> \u662f\u76f8\u540c\u7684\uff0c\u5728\u8db3\u591f\u7684\u4f18\u5316\u7ea7\u522b\u4e0a\uff0cGCC \u5b9e\u9645\u4e0a\u4f1a\u5c06\u4e24\u4e2a\u7b26\u53f7\u94fe\u63a5\u5230\u76f8\u540c\u7684\u4ee3\u7801\u3002\u56e0\u6b64\uff0c\u4e0d\u5fc5\u592a\u8fc7\u5728\u610f\u51fa\u73b0\u76f8\u540c\u7684\u6784\u9020\u51fd\u6570\u7b26\u53f7\uff0c\u53ea\u770b\u4e00\u4e2a\u5c31\u884c\u3002<\/p>\n<p>\u4e24\u4e2a\u7ffb\u8bd1\u5355\u5143\uff0c<code class=\"\" data-line=\"\">source_one.o<\/code> \u548c <code class=\"\" data-line=\"\">source_two.o<\/code> \u4e4b\u4e2d\uff0c\u4e3a\u6bcf\u4e2a\u6a21\u677f\u51fd\u6570\u90fd\u751f\u6210\u4e86\u4e00\u4e2a\u5355\u72ec\u7684\u8282\uff0c\u5e76\u5360\u636e\u7740\u4e00\u5b9a\u7684\u7a7a\u95f4\u3002\u82e5\u662f\u4e0d\u8ba1\u5176\u6570\u7684\u7ffb\u8bd1\u5355\u5143\u4e2d\u90fd\u4f7f\u7528\u8be5\u6a21\u677f\uff0c\u7f16\u8bd1\u5668\u4f1a\u4e3a\u6bcf\u4e2a\u5355\u5143\u90fd\u5b9e\u4f8b\u5316\u6a21\u677f\uff0c\u589e\u52a0\u7f16\u8bd1\u65f6\u95f4\uff0c\u91cd\u590d\u5360\u7528\u8f93\u51fa\u6587\u4ef6\u7684\u5927\u5c0f\u3002<\/p>\n<p>\u663e\u5f0f\u5b9e\u4f8b\u5316\u5982\u4f55\u907f\u514d\u8fd9\u79cd\u5f00\u9500\uff1f\u6709\u4e09\u79cd\u65b9\u5f0f\uff0c\u4e0b\u9762\u5206\u522b\u5c55\u793a\u3002<\/p>\n<p>\u7b2c\u4e00\u79cd\uff0c\u5c06\u6a21\u677f\u5b9a\u4e49\u4ece\u5934\u6587\u4ef6\u79fb\u52a8\u5230 CPP \u6e90\u6587\u4ef6\uff0c\u5934\u6587\u4ef6\u4e2d\u53ea\u7559\u4e0b\u6a21\u677f\u58f0\u660e\uff0c\u5e76\u5728\u6e90\u6587\u4ef6\u4e2d\u4f7f\u7528\u663e\u5f0f\u5b9e\u4f8b\u5316\u5b9a\u4e49\u5f3a\u5236\u7f16\u8bd1\u5668\u751f\u6210\u6a21\u677f\u5b9e\u4f8b\u3002<\/p>\n<p>\u4e5f\u5c31\u662f\u8bf4\uff0c\u5c06\u4ee3\u7801\u53d8\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ foo.h\n#ifndef FOO_H_\n#define FOO_H_\n\ntemplate&lt;class T&gt;\nclass Foo {\npublic:\n    Foo(T x);\n\n    void print();\n\nprivate:\n    T data_;\n};\n\n#endif \/\/ FOO_H_\n\n\/\/ foo.cpp\n#include &quot;foo.h&quot;\n#include &lt;iostream&gt;\n\ntemplate&lt;class T&gt;\nFoo&lt;T&gt;::Foo(T x)\n    : data_(x)\n{}\n\ntemplate&lt;class T&gt;\nvoid Foo&lt;T&gt;::print()\n{\n    std::cout &lt;&lt; &quot;x:&quot; &lt;&lt; data_ &lt;&lt; &quot;\\n&quot;;\n}\n\n\/\/ Explicit template instantiate\ntemplate class Foo&lt;int&gt;;<\/code><\/pre>\n<p>\u6b64\u65f6\u518d\u6765\u89c2\u5bdf <code class=\"\" data-line=\"\">source_one.cpp<\/code> \u548c <code class=\"\" data-line=\"\">source_two.cpp<\/code> \u751f\u6210\u76ee\u6807\u5f53\u4e2d\u7684\u7b26\u53f7\u8868\uff0c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<pre><code class=\"\" data-line=\"\">\/\/ source_one.o\n                 U Foo&lt;int&gt;::print()\n                 U Foo&lt;int&gt;::Foo(int)\n\n\/\/ source_two.o\n                 U Foo&lt;int&gt;::print()\n                 U Foo&lt;int&gt;::Foo(int)<\/code><\/pre>\n<p><code class=\"\" data-line=\"\">U<\/code> \u8868\u793a\u672a\u5b9a\u4e49\u7684\u7b26\u53f7\uff0c\u6a21\u677f\u5b9a\u4e49\u5982\u4eca\u653e\u5230\u4e86 CPP \u6e90\u6587\u4ef6\uff0c\u8fd9\u4e24\u4e2a\u7ffb\u8bd1\u5355\u5143\u65e0\u6cd5\u770b\u89c1\uff0c\u81ea\u7136\u4e0d\u4f1a\u7f16\u8bd1\uff0c\u4e5f\u6ca1\u6709\u5360\u7528\u76ee\u6807\u6587\u4ef6\u5927\u5c0f\u3002\u552f\u4e00\u7684\u4e00\u4efd\u6a21\u677f\u5b9e\u4f8b\u5728 <code class=\"\" data-line=\"\">foo.cpp<\/code> \u5f53\u4e2d\uff0c\u5b83\u4eec\u53ef\u4ee5\u4f7f\u7528\u6b64\u4efd\u5b9e\u4f8b\uff0c\u94fe\u63a5\u4e4b\u65f6\u5e76\u4e0d\u4f1a\u5b58\u5728\u95ee\u9898\u3002<\/p>\n<p>\u6dfb\u52a0\u4e00\u4e2a <code class=\"\" data-line=\"\">main.cpp<\/code> \u63d0\u4f9b\u4e3b\u51fd\u6570\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">extern void do_something1();\nextern void do_something2();\n\nint main() {\n    do_something1();\n    do_something2();\n}<\/code><\/pre>\n<p>\u94fe\u63a5\u8f93\u51fa\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"language-bash\" data-line=\"\">$&gt; g++ -o main foo.o source_one.o source_two.o main.o\n$&gt; .\/main\nx:1\nx:2<\/code><\/pre>\n<p>\u8fd9\u79cd\u65b9\u5f0f\u7684\u7f3a\u70b9\u5728\u4e8e\uff0c\u5916\u90e8\u9879\u76ee\u65e0\u6cd5\u5b9e\u4f8b\u5316\u6a21\u677f\uff0c\u53ea\u80fd\u4f7f\u7528 <code class=\"\" data-line=\"\">Foo&lt;int&gt;<\/code> \u8fd9\u4e00\u79cd\u663e\u5f0f\u5b9e\u4f8b\u5316\u7684\u6a21\u677f\u5b9e\u4f8b\u3002\u5f53\u7136\uff0c\u5018\u82e5\u4f60\u6b63\u597d\u60f3\u8981\u7981\u6b62\u7528\u6237\u5b9e\u4f8b\u5316\u6a21\u677f\uff0c\u53ea\u5141\u8bb8\u4ed6\u4eec\u4f7f\u7528\u5185\u7f6e\u7684\u67d0\u51e0\u79cd\u5b9e\u4f8b\uff0c\u53c8\u8981\u907f\u514d\u7f16\u8bd1\u5f00\u9500\uff0c\u8fd9\u4e2a\u7f3a\u70b9\u53cd\u800c\u80fd\u591f\u5229\u7528\u8d77\u6765\u3002<\/p>\n<p>\u7b2c\u4e8c\u79cd\uff0c\u6a21\u677f\u5b9a\u4e49\u4f9d\u65e7\u653e\u5728\u5934\u6587\u4ef6\u4e2d\uff0c\u4f46\u662f\u5728\u5176\u4e2d\u6dfb\u52a0\u663e\u5f0f\u5b9e\u4f8b\u5316\u58f0\u660e\u7981\u6b62\u7f16\u8bd1\u5668\u5b9e\u4f8b\u5316\u6a21\u677f\uff0c\u518d\u624b\u52a8\u4f7f\u7528\u663e\u5f0f\u5b9e\u4f8b\u5316\u5b9a\u4e49\u5f3a\u5236\u7f16\u8bd1\u5668\u751f\u6210\u60f3\u8981\u7684\u6a21\u677f\u5b9e\u4f8b\u3002<\/p>\n<p>\u5177\u4f53\u6765\u8bf4\uff0c\u5c06\u4ee3\u7801\u53d8\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ foo.h\n#ifndef FOO_H_\n#define FOO_H_\n\n#include &lt;iostream&gt;\n\ntemplate&lt;class T&gt;\nclass Foo {\npublic:\n    Foo(T x) : data_(x) {}\n\n    void print() const {\n        std::cout &lt;&lt; &quot;x:&quot; &lt;&lt; data_ &lt;&lt; &quot;\\n&quot;;\n    }\n\nprivate:\n    T data_;\n};\n\n\/\/ Explicit template declaration\nextern template class Foo&lt;int&gt;;\n\n#endif \/\/ FOO_H_<\/code><\/pre>\n<p>\u7136\u540e\uff0c\u5728 <code class=\"\" data-line=\"\">source_one.cpp<\/code> \u663e\u5f0f\u5b9e\u4f8b\u5316\u6a21\u677f\uff0c<code class=\"\" data-line=\"\">source_two.cpp<\/code> \u4e2d\u4ec0\u4e48\u90fd\u4e0d\u505a\u3002\u4ee3\u7801\u53d8\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ source_one.cpp\n#include &quot;foo.h&quot;\n\ntemplate class Foo&lt;int&gt;;\n\nvoid do_something1() {\n    Foo&lt;int&gt; foo(1);\n    foo.print();\n}\n\n\/\/ source_two.cpp\n#include &quot;foo.h&quot;\n\nvoid do_something2() {\n    Foo&lt;int&gt; foo(2);\n    foo.print();\n}<\/code><\/pre>\n<p>\u4e8e\u662f\uff0c\u5f53\u524d\u53ea\u6709 <code class=\"\" data-line=\"\">source_one.cpp<\/code> \u4e2d\u5b9e\u9645\u751f\u6210\u4e86\u6a21\u677f\u5b9e\u4f8b\uff0c<code class=\"\" data-line=\"\">source_two.cpp<\/code> \u4e2d\u6ca1\u6709\u6a21\u677f\u5b9e\u4f8b\u3002\u67e5\u770b\u76ee\u6807\u6587\u4ef6\u7b26\u53f7\u8868\uff0c\u5185\u5bb9\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ source_one.o\n0000000000000000 000000000000001b W Foo&lt;int&gt;::Foo(int)\n0000000000000000 000000000000001b W Foo&lt;int&gt;::Foo(int)\n0000000000000000 n Foo&lt;int&gt;::Foo(int)\n0000000000000000 0000000000000048 W Foo&lt;int&gt;::print() const\n\n\/\/ source_two.o\n                 U Foo&lt;int&gt;::Foo(int)\n                 U Foo&lt;int&gt;::print() const<\/code><\/pre>\n<p>\u53ef\u89c1\u4e8b\u5b9e\u7684\u786e\u5982\u6b64\u3002\u82e5\u662f\u73b0\u5728\u94fe\u63a5\u8fd9\u4e24\u4e2a\u76ee\u6807\u6587\u4ef6\uff0c\u5176\u4e2d\u4e5f\u53ea\u4f1a\u5b58\u5728\u4e00\u4efd\u5b9e\u4f8b\uff08\u4f46\u662f\u6ca1\u6709\u5254\u9664\u64cd\u4f5c\uff0c\u672c\u6765\u5c31\u53ea\u5b58\u5728\u4e00\u4efd\u6a21\u677f\u5b9e\u4f8b\uff09\uff1a<\/p>\n<pre><code class=\"language-bash\" data-line=\"\">$&gt; ld -r -o source.o source_one.o source_two.o\n$&gt; nm -C source.o\n                 U _GLOBAL_OFFSET_TABLE_\n000000000000009c t _GLOBAL__sub_I__Z13do_something1v\n0000000000000151 t _GLOBAL__sub_I__Z13do_something2v\n0000000000000000 T do_something1()\n00000000000000b5 T do_something2()\n000000000000004f t __static_initialization_and_destruction_0(int, int)\n0000000000000104 t __static_initialization_and_destruction_0(int, int)\n0000000000000000 W Foo&lt;int&gt;::Foo(int)\n0000000000000000 W Foo&lt;int&gt;::Foo(int)\n0000000000000000 n Foo&lt;int&gt;::Foo(int)\n0000000000000000 W Foo&lt;int&gt;::print() const\n                 U std::ostream::operator&lt;&lt;(int)\n                 U std::ios_base::Init::Init()\n                 U std::ios_base::Init::~Init()\n                 U std::cout\n0000000000000000 r std::piecewise_construct\n0000000000000006 r std::piecewise_construct\n0000000000000000 b std::__ioinit\n0000000000000001 b std::__ioinit\n                 U std::basic_ostream&lt;char, std::char_traits&lt;char&gt; &gt;&amp; std::operator&lt;&lt; &lt;std::char_traits&lt;char&gt; &gt;(std::basic_ostream&lt;char, std::char_traits&lt;char&gt; &gt;&amp;, char const*)\n                 U __cxa_atexit\n                 U __dso_handle\n                 U __stack_chk_fail\n<\/code><\/pre>\n<p>\u63a5\u7740\uff0c\u518d\u5c06\u8fd9\u4e24\u4e2a\u6587\u4ef6\u548c <code class=\"\" data-line=\"\">main.cpp<\/code> \u94fe\u63a5\uff0c\u8f93\u51fa\u53ef\u6267\u884c\u6587\u4ef6\uff0c\u770b\u7a0b\u5e8f\u662f\u5426\u80fd\u591f\u6b63\u5e38\u8fd0\u884c\u3002<\/p>\n<pre><code class=\"\" data-line=\"\">$&gt; g++ -o main source_two.o source_one.o main.o\n$&gt; .\/main\nx:1\nx:2<\/code><\/pre>\n<p>\u4e00\u5207\u6b63\u5e38\uff0c\u8fd9\u79cd\u65b9\u5f0f\u7684\u786e\u6709\u6548\u3002\u4f46\u662f\u4e5f\u6709\u4e00\u4e9b\u7f3a\u70b9\uff0c\u5c06\u6240\u6709\u6a21\u677f\u5b9a\u4e49\u5728\u4e00\u4e2a\u5355\u72ec\u7684\u5934\u6587\u4ef6\u5f53\u4e2d\uff0c\u8be5\u6587\u4ef6\u7a0d\u6709\u52a8\u6539\uff0c\u4f9d\u8d56\u7684\u6240\u6709\u6587\u4ef6\u90fd\u5f97\u91cd\u65b0\u7f16\u8bd1\u3002\u518d\u8005\uff0c\u8fd9\u79cd header-only \u7684\u65b9\u5f0f\uff0c\u8feb\u4f7f\u7528\u6237\u81ea\u5df1\u5b9e\u4f8b\u5316\u6a21\u677f\uff0c\u5c06 header-only \u53bb\u9664\uff0c\u628a\u5b9e\u4f8b\u5316\u653e\u5230 CPP \u6e90\u6587\u4ef6\u4e2d\u53ef\u4ee5\u907f\u514d\u8be5\u95ee\u9898\u3002\u6b64\u5916\uff0c\u6a21\u677f\u7c7b\u578b\u82e5\u662f\u81ea\u5b9a\u4e49\u7c7b\u578b\uff0c\u5219\u4f1a\u5f3a\u5236\u7528\u6237\u5305\u542b\u5305\u542b\u8be5\u7c7b\u578b\uff0c\u65e0\u6cd5\u901a\u8fc7\u524d\u7f6e\u58f0\u660e\u89e3\u51b3\uff0c\u5934\u6587\u4ef6\u4f9d\u8d56\u6027\u589e\u52a0\u3002<\/p>\n<p>\u7b2c\u4e09\u79cd\uff0c\u6a21\u677f\u5b9a\u4e49\u4f9d\u65e7\u653e\u5728\u5934\u6587\u4ef6\u4e2d\uff0c\u6bcf\u4e2a\u5305\u542b\u8005\u589e\u52a0\u663e\u5f0f\u5b9e\u4f8b\u5316\u58f0\u660e\u7981\u6b62\u9690\u5f0f\u5b9e\u4f8b\u5316\u6a21\u677f\u3002<\/p>\n<p>\u6b64\u65f6\uff0c\u6a21\u677f\u5934\u6587\u4ef6\u5c31\u662f\u672c\u8282\u6700\u5f00\u59cb\u7684\u539f\u59cb\u5b9e\u73b0\uff0c\u65e0\u9700\u6539\u53d8\uff0c\u5728 <code class=\"\" data-line=\"\">foo.cpp<\/code> \u4e2d\u5199\u5165\u663e\u5f0f\u5b9e\u4f8b\u5316\u5b9a\u4e49\u3002\u4e8e\u662f\uff0c\u4ee3\u7801\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ foo.cpp\n#include &quot;foo.h&quot;\n\ntemplate class Foo&lt;int&gt;;<\/code><\/pre>\n<p>\u518d\u5728\u6bcf\u4e2a\u5305\u542b\u6a21\u677f\u5934\u6587\u4ef6\u7684\u6e90\u6587\u4ef6\u4e2d\uff0c\u4f7f\u7528\u663e\u5f0f\u5b9e\u4f8b\u5316\u58f0\u660e\u7981\u6b62\u7f16\u8bd1\u5668\u751f\u6210\u6a21\u677f\u5b9e\u4f8b\u3002\u5b9e\u73b0\u53d8\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ source_one.cpp\n#include &quot;foo.h&quot;\n\n\/\/ Explicit template declaration\nextern template class Foo&lt;int&gt;;\n\nvoid do_something1() {\n    Foo&lt;int&gt; foo(1);\n    foo.print();\n}\n\n\/\/ source_two.cpp\n#include &quot;foo.h&quot;\n\n\/\/ Explicit template declaration\nextern template class Foo&lt;int&gt;;\n\nvoid do_something2() {\n    Foo&lt;int&gt; foo(2);\n    foo.print();\n}<\/code><\/pre>\n<p>\u7f16\u8bd1\u751f\u6210\u76ee\u6807\u6587\u4ef6\uff0c\u518d\u6b21\u67e5\u770b\u7b26\u53f7\u8868\uff0c\u5185\u5bb9\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ source_one.o\n                 U Foo&lt;int&gt;::Foo(int)\n                 U Foo&lt;int&gt;::print() const\n\/\/ source_two.o\n                 U Foo&lt;int&gt;::Foo(int)\n                 U Foo&lt;int&gt;::print() const<\/code><\/pre>\n<p>\u53ef\u89c1\uff0c\u8fd9\u4e24\u4e2a\u7ffb\u8bd1\u5355\u5143\u6ca1\u6709\u5b9e\u4f8b\u5316\u6a21\u677f\u3002<\/p>\n<p>\u6700\u540e\uff0c\u94fe\u63a5\u6240\u6709\u6587\u4ef6\uff0c\u67e5\u770b\u7ed3\u679c\u662f\u5426\u6b63\u5e38\u3002<\/p>\n<pre><code class=\"language-bash\" data-line=\"\">$&gt; g++ -o main foo.o source_one.o source_two.o main.o\n$&gt; .\/main\nx:1\nx:2<\/code><\/pre>\n<p>\u7ed3\u679c\u4f9d\u65e7\u4e0d\u5b58\u5728\u95ee\u9898\u3002\u8fd9\u79cd\u65b9\u5f0f\u7684\u7f3a\u70b9\u5f88\u660e\u663e\uff0c\u6bcf\u4e2a\u4f7f\u7528\u8005\u90fd\u9700\u8981\u5728\u6e90\u6587\u4ef6\u4e2d\u4f7f\u7528\u663e\u5f0f\u5b9e\u4f8b\u5316\u58f0\u660e\u4ee5\u7981\u6b62\u7f16\u8bd1\u5668\u751f\u6210\u6a21\u677f\u5b9e\u4f8b\uff0c\u800c\u4ed6\u4eec\u53ef\u80fd\u4f1a\u5728\u4e0d\u7ecf\u610f\u95f4\u5fd8\u8bb0\u3002<\/p>\n<p>\u672c\u8282\u81f3\u6b64\u7ed3\u675f\uff0c\u5173\u4e8e\u9690\u5f0f\u5b9e\u4f8b\u5316\uff0c\u5c31\u662f\u6a21\u677f\u53c2\u6570\u63a8\u5bfc\u548c\u6a21\u677f\u53c2\u6570\u66ff\u6362\u8fd9\u4e2a\u6d41\u7a0b\uff0c\u8001\u751f\u5e38\u8c08\uff0c\u89c1 <a href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/github.com\/lkimuk\/the-book-of-modern-cpp\">[The Book of Modern C++]\/p63<\/a>\u3002<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E6%A8%A1%E6%9D%BF%E5%8F%82%E6%95%B0\"><\/span>\u6a21\u677f\u53c2\u6570<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u672c\u8282\u4ecb\u7ecd\u6a21\u677f\u53c2\u6570\uff0c\u5c5e\u4e8e\u6a21\u677f\u7684\u8f93\u5165\uff0c\u4e5f\u5c31\u662f\u62bd\u8c61\u7684\u6570\u636e\u7c7b\u578b\u3002<\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E6%A8%A1%E6%9D%BF%E5%8F%82%E6%95%B0%E7%9A%84%E7%B1%BB%E5%9E%8B\"><\/span>\u6a21\u677f\u53c2\u6570\u7684\u7c7b\u578b<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u6a21\u677f\u53c2\u6570\u7c7b\u578b\u53ef\u4ee5\u5206\u6210\u5982\u4e0b\u516d\u79cd\uff1a<\/p>\n<ul>\n<li>Type<\/li>\n<li>NonType<\/li>\n<li>Type template<\/li>\n<li>Variable template<\/li>\n<li>Concept<\/li>\n<li>Universal<\/li>\n<\/ul>\n<p>\u7528\u4ee3\u7801\u8868\u793a\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;\n  typename Type,                                \/\/ Type\n  auto NonType,                                 \/\/ Non-type\n  template&lt;template auto...&gt; class Temp,        \/\/ Type template\n  template&lt;template auto...&gt; auto Var,          \/\/ Variable template\n  template&lt;template auto...&gt; concept Concept,   \/\/ Concept\n  template auto Universal                       \/\/ Universal\n&gt;<\/code><\/pre>\n<p>\u5f53\u7136\uff0c\u76ee\u524d C++ \u6807\u51c6\u5c1a\u4e0d\u652f\u6301\u5168\u90e8\u7684\u516d\u79cd\u7c7b\u578b\uff0c\u672c\u8282\u53ea\u770b\u524d\u4e09\u79cd\u3002<\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E7%B1%BB%E5%9E%8B%E5%8F%82%E6%95%B0%EF%BC%88Type%EF%BC%89\"><\/span>\u7c7b\u578b\u53c2\u6570\uff08Type\uff09<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u8fd9\u79cd\u6a21\u677f\u53c2\u6570\u7684\u7c7b\u578b\u5fc5\u987b\u662f\u4e00\u4e2a type-id\uff0c\u5e73\u65f6\u6a21\u677f\u4ee3\u7801\u4e2d\u4f7f\u7528\u7684\u5c31\u662f\u6b64\u7c7b\u53c2\u6570\u3002<\/p>\n<p>\u4f8b\u5982\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ Example from ISO C++\ntemplate&lt;class T&gt; class X {};\ntemplate&lt;class T&gt; void f(T t) {}\n\nstruct {} unnamed_obj;\n\nvoid f() {\n    struct A {};\n    enum { e1 };\n    typedef struct {} B;\n    B b;\n    X&lt;A&gt; x1;        \/\/ OK\n    X&lt;A*&gt; x2;       \/\/ OK\n    X&lt;B&gt; x3;        \/\/ OK\n    f(e1);          \/\/ OK\n    f(unnamed_obj); \/\/ OK\n    f(b);           \/\/ OK\n}<\/code><\/pre>\n<p>\u82e5\u662f\u6a21\u677f\u5b58\u5728\u7c7b\u578b\u53c2\u6570\u548c\u975e\u7c7b\u578b\u53c2\u6570\u7684\u91cd\u8f7d\uff0ctype-id \u4e0e\u8868\u8fbe\u5f0f\u4ea7\u751f\u5c06\u4ea7\u751f\u6b67\u4e49\uff0c\u6b64\u65f6\u53c2\u6570\u7c7b\u578b\u89e3\u6790\u4e3a type-id\uff0c\u5373\u7c7b\u578b\u53c2\u6570\u3002<\/p>\n<p>\u4f8b\u5982\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ Example from ISO C++\ntemplate&lt;class T&gt; void f();\ntemplate&lt;int I&gt; void f();\n\nvoid g() {\n    f&lt;int()&gt;(); \/\/ int() is a type-id: call the first f()\n}<\/code><\/pre>\n<h3><span class=\"ez-toc-section\" id=\"%E9%9D%9E%E7%B1%BB%E5%9E%8B%E5%8F%82%E6%95%B0%EF%BC%88Non-Type%EF%BC%89\"><\/span>\u975e\u7c7b\u578b\u53c2\u6570\uff08Non-Type\uff09<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u8fd9\u79cd\u6a21\u677f\u53c2\u6570\u4e00\u822c\u79f0\u4e3a NTTP(Non-Type Template Parameter)\u3002C++20 \u4e4b\u524d\uff0cNTTP \u88ab\u9650\u5236\u4e3a\uff1a<\/p>\n<blockquote>\n<ul>\n<li>lvalue reference type (to object or to function);<\/li>\n<li>an integral type;<\/li>\n<li>a pointer type (to object or to function);<\/li>\n<li>a pointer to member type (to member object or to member function);<\/li>\n<li>an enumeration type;<\/li>\n<li>std::nullptr_t (since c++11)<\/li>\n<\/ul>\n<\/blockquote>\n<p>C++20 \u4e4b\u540e\uff0cNTTP \u8fdb\u4e00\u6b65\u6269\u5c55\u4e3a\uff1a<\/p>\n<blockquote>\n<ul>\n<li>an floating-point type;<\/li>\n<li>a literal class type with the following properties:<\/li>\n<li>all base classes and non-static data members are public and non-mutable and<\/li>\n<li>the types of all bases classes and non-static data members are structural types or (possibly multi-dimensional) array thereof.<\/li>\n<\/ul>\n<p>from <a href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/en.cppreference.com\/w\/cpp\/language\/template_parameters\">https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/en.cppreference.com\/w\/cpp\/language\/template_parameters<\/a><\/p>\n<\/blockquote>\n<p>NTTP \u4f5c\u4e3a\u6a21\u677f\u53c2\u6570\uff0c\u4f1a\u8f6c\u6362\u6210\u6a21\u677f\u53c2\u6570\u7c7b\u578b\u7684\u5e38\u91cf\u8868\u8fbe\u5f0f\u3002NTTP \u7c7b\u578b\u4e0d\u662f\u62bd\u8c61\u7c7b\u578b\uff0c\u800c\u662f\u5177\u4f53\u7c7b\u578b\u7684\u5e38\u91cf\u8868\u8fbe\u5f0f\uff0c\u6240\u4ee5\u79f0\u4e3a\u975e\u7c7b\u578b\u6a21\u677f\u53c2\u6570\u3002<\/p>\n<p>\u5982\u679c NTTP \u662f\u5f15\u7528\u6216\u6307\u9488\uff0c\u5f15\u7528\u6216\u6307\u5411\u7684\u503c\u4e0d\u80fd\u662f\uff1a<\/p>\n<blockquote>\n<ul>\n<li>a temporary object;<\/li>\n<li>a string literal object;<\/li>\n<li>the result of a <code class=\"\" data-line=\"\">typeid<\/code> expression<\/li>\n<li>a predefined <code class=\"\" data-line=\"\">__func__<\/code> variable;<\/li>\n<li>a subobject of one of the above.<\/li>\n<\/ul>\n<p>from ISO\/IEC C++ 2020 13.4.2\/4<\/p>\n<\/blockquote>\n<p>\u4f8b\u5982\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ Example from ISO C++\ntemplate&lt;const int* pci&gt; struct X {};\nint ai[10];\nX&lt;ai&gt; xi; \/\/ array to pointer and qualification conversions\n\nstruct Y {};\ntemplate&lt;const Y&amp; b&gt; struct Z {};\nY y;\nZ&lt;y&gt; z;               \/\/ no conversion, but note extra cv-qualification\n\ntemplate&lt;int (&amp;pa)[5]&gt; struct W {};\nint b[5];\nW&lt;b&gt; w;               \/\/ no conversion\n\nvoid f(char);\nvoid f(int);\n\ntemplate&lt;void (*pf)(int)&gt; struct A {};\n\nA&lt;&amp;f&gt; a;              \/\/ selects f(int)\n\ntemplate&lt;auto n&gt; struct B {};\nB&lt;5&gt; b1;              \/\/ OK, template parameter type is int\nB&lt;&#039;a&#039;&gt; b2;            \/\/ OK, template parameter type is char\nB&lt;2.5&gt; b3;            \/\/ OK since C++20, template parameter type is double\nB&lt;void(0)&gt; b4;        \/\/ error, template parameter type cannot be void<\/code><\/pre>\n<p>\u518d\u6765\u770b\u4e00\u4e2a\u4e34\u65f6\u5bf9\u8c61\u7684\u4f8b\u5b50\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ Example from ISO C++\ntemplate&lt;const int&amp; CRI&gt; struct B {};\n\nB&lt;1&gt; b1;        \/\/ error: temporary would be required for template argument\n\nint c = 1;\nB&lt;c&gt; b2;        \/\/ OK\n\nstruct X { int n; };\nstruct Y { const int &amp;r; };\ntemplate&lt;Y y&gt; struct C {};\nC&lt;Y{X{1}.n}&gt; c; \/\/ error: subobject of temporary object used to initialize\n                \/\/ reference member of template parameter<\/code><\/pre>\n<p>\u6700\u540e\uff0c\u9700\u8981\u6ce8\u610f\uff0cstring-literal \u4e0d\u80fd\u76f4\u63a5\u7528\u4f5c NTTP\uff0c\u4f46\u53ef\u4ee5\u95f4\u63a5\u901a\u8fc7\u5e38\u91cf\u6307\u9488\u6216\u4f5c\u4e3a\u7c7b\u7684\u6784\u9020\u51fd\u6570\u53c2\u6570\u6765\u4f7f\u7528\u3002<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ Example from ISO C++\ntemplate&lt;class T, T p&gt; class X {};\n\nX&lt;const char*, &quot;Studebaker&quot;&gt; x; \/\/ error: string literal object as template-argument\nX&lt;const char*, &quot;Knope&quot; + 1&gt; x2; \/\/ error: subobject of string literal object as template-argument\n\nconst char p[] = &quot;Vivisectionist&quot;;\nX&lt;const char*, p&gt; y;            \/\/ OK\n\nstruct A {\n    constexpr A(const char*) {}\n};\n\nX&lt;A, &quot;Pyrophoricity&quot;&gt; z;       \/\/ OK, string-literal is a constructor argument to A<\/code><\/pre>\n<h3><span class=\"ez-toc-section\" id=\"%E7%B1%BB%E5%9E%8B%E6%A8%A1%E6%9D%BF%E5%8F%82%E6%95%B0%EF%BC%88Type_template%EF%BC%89\"><\/span>\u7c7b\u578b\u6a21\u677f\u53c2\u6570\uff08Type template\uff09<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u8fd9\u662f\u6a21\u677f Type \u53c2\u6570\u7684\u590d\u6742\u5f62\u5f0f\uff0c\u4e5f\u5c31\u662f template template arguments\u3002<\/p>\n<p>\u6b64\u79cd\u60c5\u51b5\u4e0b\uff0c\u6a21\u677f\u5b9e\u53c2\u53ea\u80fd\u662f\u7c7b\u6a21\u677f\u6216\u522b\u540d\u6a21\u677f\u3002\u5f53\u6a21\u677f\u5b9e\u53c2\u662f\u7c7b\u6a21\u677f\u65f6\uff0c\u5f62\u53c2\u5339\u914d\u53ea\u4f1a\u8003\u8651\u4e3b\u6a21\u677f\uff0c\u504f\u7279\u5316\u6a21\u677f\u4ec5\u5728\u57fa\u4e8e\u6b64\u6a21\u677f\u6a21\u677f\u5f62\u53c2\u5b9e\u4f8b\u5316\u65f6\u624d\u4f1a\u88ab\u8003\u8651\u3002<\/p>\n<p>\u4f8b\u5982\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/\/ Example from ISO C++\n\n\/\/ primary template\ntemplate&lt;class T&gt; class A {\n    int x;\n};\n\n\/\/ partial specialization\ntemplate&lt;class T&gt; class A&lt;T*&gt; {\n    long x;\n};\n\ntemplate&lt;template&lt;class U&gt; class V&gt; class C {\n    V&lt;int&gt; y;\n    V&lt;int*&gt; z;\n};\n\n\/\/ V&lt;int&gt; within C&lt;A&gt; uses the primary template, so c.y.x has type int\n\/\/ V&lt;int*&gt; within C&lt;A&gt; uses the partial specialization, so c.z.x has type long\nC&lt;A&gt; c;<\/code><\/pre>\n<p>\u6a21\u677f\u5b9e\u53c2\u548c\u6a21\u677f\u6a21\u677f\u5f62\u53c2\u5339\u914d\u65f6\uff0c\u540e\u8005\u81f3\u5c11\u8981\u4e0e\u524d\u8005\u540c\u7b49\u7279\u6b8a\u3002\u7b80\u5355\u6765\u8bf4\uff0c\u5c31\u662f\u5f62\u53c2 <code class=\"\" data-line=\"\">P<\/code> \u4e0d\u80fd\u6bd4\u5b9e\u53c2 <code class=\"\" data-line=\"\">A<\/code> \u66f4\u52a0\u62bd\u8c61\u3002\u8fd9\u662f C++17 \u624d\u4fee\u590d\u7684\u4e00\u4e2a\u95ee\u9898\uff0c\u4e4b\u524d <code class=\"\" data-line=\"\">P<\/code> \u4e0e <code class=\"\" data-line=\"\">A<\/code> \u5fc5\u987b\u5b8c\u5168\u5339\u914d\uff0c\u5bfc\u81f4\u4e00\u4e9b\u5408\u7406\u7684\u5b9e\u53c2\u65e0\u6cd5\u5339\u914d\u3002\u6bd4\u5982\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template &lt;template &lt;typename&gt; class&gt; void FD();\ntemplate &lt;typename, typename = int&gt; struct SD { \/* ... *\/ };\nFD&lt;SD&gt;();  \/\/ OK; error before C++17<\/code><\/pre>\n<p>C++17 \u4e4b\u540e\uff0c\u53ea\u8981\u6ee1\u8db3\u540c\u7b49\u7279\u6b8a\u7684\u89c4\u5219\uff0c<code class=\"\" data-line=\"\">P<\/code> \u4e0e <code class=\"\" data-line=\"\">A<\/code> \u5c31\u80fd\u591f\u5339\u914d\uff0c\u5982\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template &lt;template &lt;int&gt; class&gt; void FI();\ntemplate &lt;template &lt;auto&gt; class&gt; void FA();\ntemplate &lt;auto&gt; struct SA {};\ntemplate &lt;int&gt; struct SI {};\nFI&lt;SA&gt;();  \/\/ OK; error before C++17\nFA&lt;SI&gt;();  \/\/ error<\/code><\/pre>\n<p>\u5bf9\u4e8e <code class=\"\" data-line=\"\">FI&lt;SA&gt;()<\/code>\uff0c\u6a21\u677f\u6a21\u677f\u5f62\u53c2 <code class=\"\" data-line=\"\">P<\/code> \u662f <code class=\"\" data-line=\"\">int<\/code>\uff0c\u800c\u6a21\u677f\u5b9e\u53c2 <code class=\"\" data-line=\"\">A<\/code> \u662f <code class=\"\" data-line=\"\">auto<\/code>\uff0c\u524d\u8005\u6bd4\u540e\u8005\u7279\u6b8a\uff0c\u8fd9\u53eb\u81f3\u5c11\u540c\u7b49\u7279\u6b8a\u3002\u524d\u8005\u7684\u7279\u6b8a\u6027\u53ea\u8981\u5c0f\u4e8e\u7b49\u4e8e\u540e\u8005\uff0c\u5c31\u53eb\u540c\u7b49\u7279\u6b8a\uff0c\u5426\u5219\u4fbf\u5339\u914d\u5931\u8d25\uff0c\u4f8b\u5982 <code class=\"\" data-line=\"\">FA&lt;SI&gt;()<\/code>\u3002<\/p>\n<p>\u4e0b\u9762\u63d0\u4f9b\u66f4\u591a\u4f8b\u5b50\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;class T&gt; class A {};\ntemplate&lt;class T, class U = T&gt; class B {};\ntemplate&lt;class... Types&gt; class C {};\ntemplate&lt;auto n&gt; class D {};\n\ntemplate&lt;template&lt;class&gt; class P&gt; class X {};\ntemplate&lt;template&lt;class...&gt; class Q&gt; class Y {};\ntemplate&lt;template&lt;int&gt; class R&gt; class Z {};\n\nX&lt;A&gt; xa; \/\/ OK\nX&lt;B&gt; xb; \/\/ OK since C++17\nX&lt;C&gt; xc; \/\/ OK since C++17\nY&lt;A&gt; ya; \/\/ OK\nY&lt;B&gt; yb; \/\/ OK\nY&lt;C&gt; yc; \/\/ OK\nZ&lt;D&gt; zd; \/\/ OK since C++17<\/code><\/pre>\n<p>\u518d\u6765\u770b\u4e00\u4e2a\u7279\u6b8a\u7684\u4f8b\u5b50\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">\/\/ Example from https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/stackoverflow.com\/questions\/72911910\/exact-rules-for-matching-variadic-template-template-parameters-in-partial-templa\n#include &lt;variant&gt;\n#include &lt;iostream&gt;\n\ntemplate&lt;typename T&gt;\nstruct TypeChecker {\n    void operator()() {\n        std::cout &lt;&lt; &quot;I am other type\\n&quot;;\n    }\n};\n\ntemplate&lt;typename ... Ts, template&lt;typename&gt; typename V&gt;\nrequires std::same_as&lt;V&lt;Ts...&gt;, std::variant&lt;Ts...&gt;&gt;\nstruct TypeChecker&lt;V&lt;Ts...&gt;&gt;\n{\n    void operator()()\n    {\n        std::cout &lt;&lt; &quot;I am std::variant\\n&quot;;\n    }\n};\n\nint main()\n{\n    TypeChecker&lt;std::variant&lt;int, float&gt;&gt;{}();\n    TypeChecker&lt;std::variant&lt;float&gt;&gt;{}();\n    TypeChecker&lt;int&gt;{}();\n}<\/code><\/pre>\n<p>\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\u6a21\u677f\u6a21\u677f\u5f62\u53c2\u548c\u6a21\u677f\u5b9e\u53c2\u662f\u5426\u6ee1\u8db3\u81f3\u5c11\u540c\u7b49\u7279\u6b8a\u539f\u5219\uff1fP \u662f <code class=\"\" data-line=\"\">template&lt;typename&gt; typename V<\/code>\uff0cA \u662f <code class=\"\" data-line=\"\">std::variant&lt;Ts...&gt;<\/code>\uff0c\u770b\u7740\u65e0\u6cd5\u5b8c\u5168\u5339\u914d\uff0c\u5b9e\u9645\u4e0a P \u4e0e A \u6ee1\u8db3\u81f3\u5c11\u540c\u7b49\u7279\u6b8a\u539f\u5219\u3002\u56e0\u6b64\u8f93\u51fa\u5e94\u8be5\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">I am std::variant\nI am std::variant\nI am other type<\/code><\/pre>\n<p>\u7136\u800c\uff0c\u53ea\u6709 GCC \u548c MSVC \u9ed8\u8ba4\u4f1a\u6709\u4ee5\u4e0a\u7ed3\u679c\uff0c Clang \u7684\u8f93\u51fa\u90fd\u662f <code class=\"\" data-line=\"\">I am other type<\/code>\u3002\u53ea\u56e0\u5176\u9ed8\u8ba4\u6ca1\u6709\u5e94\u7528 C++17 \u8fd9\u4e2a\u4fee\u590d\u7684\u5339\u914d\u89c4\u5219\uff0c\u52a0\u4e0a <code class=\"\" data-line=\"\">-frelaxed-template-template-args<\/code> \u7f16\u8bd1\u6807\u5fd7\uff0c\u5219\u53ef\u5f97\u5230\u6b63\u5e38\u8f93\u51fa\u3002\u6b64\u5916\uff0c\u5728 C++17 \u4ee5\u524d\uff0cGCC \u53ef\u4ee5\u6dfb\u52a0 <code class=\"\" data-line=\"\">-fnew-ttp-matching<\/code> \u6807\u5fd7\u6765\u5f97\u5230\u65b0\u7684\u5339\u914d\u7ed3\u679c\u3002<\/p>\n<p>\u540c\u65f6\u4e5f\u9700\u6ce8\u610f\uff0c\u5b9e\u53c2\u5e76\u975e\u4e00\u5b9a\u8981\u662f\u4f8b\u5b50\u4e2d\u7684 <code class=\"\" data-line=\"\">std::variant<\/code>\uff0c\u5176\u4ed6\u652f\u6301\u53ef\u53d8\u6a21\u677f\u53c2\u6570\u7684\u7c7b\u540c\u6837\u9002\u7528\uff0c\u5982 <code class=\"\" data-line=\"\">std::tuple<\/code>\uff0c\u6216\u81ea\u5b9a\u4e49\u7c7b\u578b <code class=\"\" data-line=\"\">template&lt;class...&gt; struct S<\/code>\u3002<\/p>\n<p>\u6700\u540e\uff0c\u518d\u6765\u770b\u4e24\u4e2a\u4f8b\u5b50\uff0c\u7ed3\u675f\u672c\u8282\u3002<\/p>\n<p>\u4f8b\u5b50\u4e00\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;class T&gt; struct eval;\n\ntemplate&lt;template&lt;class, class...&gt; class TT, class T1, class... Rest&gt;\nstruct eval&lt;TT&lt;T1, Rest...&gt;&gt; {};\n\ntemplate&lt;class T1&gt; struct A;\ntemplate&lt;class T1, class T2&gt; struct B;\ntemplate&lt;int N&gt; struct C;\ntemplate&lt;class T1, int N&gt; struct D;\ntemplate&lt;class T1, class T2, int N = 17&gt; struct E;\n\neval&lt;A&lt;int&gt;&gt; eA;        \/\/ OK: matches partial specialization of eval\neval&lt;B&lt;int, float&gt;&gt; eB; \/\/ OK: matches partial specialization of eval\neval&lt;C&lt;17&gt;&gt; eC;         \/\/ error: C does not match TT in partial specialization\neval&lt;D&lt;int, 17&gt; eD;     \/\/ error: D does not match TT in partial specialization\neval&lt;E&lt;int, float&gt;&gt; eE; \/\/ error: E does not match TT in partial specialization<\/code><\/pre>\n<p>\u6a21\u677f\u5f62\u53c2\u548c\u5b9e\u53c2\u4e0d\u5339\u914d\uff0c\u5b9e\u53c2\u4e2d\u7684\u975e\u7c7b\u578b\u53c2\u6570\u6bd4\u6a21\u677f\u5f62\u53c2\u66f4\u7279\u6b8a\uff0c\u4e8e\u662f\u51fa\u9519\u3002<\/p>\n<p>\u4f8b\u5b50\u4e8c\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;typename T&gt; concept C = requires (T t) { t.f(); };\ntemplate&lt;typename T&gt; concept D = C&lt;T&gt; &amp;&amp; requires (T t) { t.g(); };\n\ntemplate&lt;template&lt;C&gt; class P&gt; struct S {};\n\ntemplate&lt;C&gt; struct X {};\ntemplate&lt;D&gt; struct Y {};\ntemplate&lt;typename T&gt; struct Z {};\n\nS&lt;X&gt; s1; \/\/ OK, X and P have equivalent constraints\nS&lt;Y&gt; s2; \/\/ error: P is not at least as specialized as Y\nS&lt;Z&gt; s3; \/\/ OK, P is at least as specialized as Z<\/code><\/pre>\n<p>\u5f53\u6709 Concept \u7ea6\u675f\u65f6\uff0c\u81f3\u5c11\u540c\u7b49\u7279\u6b8a\u539f\u5219\u66f4\u6613\u8bc6\u522b\u3002\u82e5\u662f\u6a21\u677f\u6a21\u677f\u5f62\u53c2\u548c\u6a21\u677f\u5b9e\u53c2\u7684\u7ea6\u675f\u4e00\u81f4\uff0c\u5219\u7ea6\u675f\u7b49\u4ef7\uff1b\u82e5\u6a21\u677f\u6a21\u677f\u5f62\u53c2\u6bd4\u6a21\u677f\u5b9e\u53c2\u7684\u7ea6\u675f\u591a\u4e00\u4e9b\uff0c\u5219\u4e0d\u6ee1\u8db3\u81f3\u5c11\u540c\u7b49\u7279\u6b8a\u539f\u5219\uff1b\u82e5\u6a21\u677f\u6a21\u677f\u5f62\u53c2\u6bd4\u6a21\u677f\u5b9e\u53c2\u7684\u7ea6\u675f\u5c11\u4e00\u4e9b\uff0c\u5219\u6ee1\u8db3\u3002<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E5%AE%9E%E7%8E%B0_make_index_sequence_%E5%B1%95%E7%8E%B0%E5%87%BA%E7%9A%84%E5%90%84%E7%A7%8D%E6%A8%A1%E6%9D%BF%E6%8A%80%E6%9C%AF\"><\/span>\u5b9e\u73b0 make_index_sequence \u5c55\u73b0\u51fa\u7684\u5404\u79cd\u6a21\u677f\u6280\u672f<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u672c\u8282\u4ee5\u5b9e\u73b0 <code class=\"\" data-line=\"\">make_index_sequence<\/code> \u4f5c\u4e3a\u95ee\u9898\uff0c\u5c55\u793a\u8bf8\u591a\u7ecf\u5178\u7684\u6a21\u677f\u6280\u672f\u3002<\/p>\n<p>\u9700\u8981\u6ce8\u610f\uff0c\u6b64\u5904\u5e76\u672a\u53c2\u8003 <code class=\"\" data-line=\"\">std::make_index_sequence<\/code> \u7684\u5b9e\u73b0\uff0c\u6807\u51c6\u5b9e\u73b0\u4e00\u822c\u8003\u8651\u5f97\u66f4\u52a0\u5468\u5230\uff0c\u672c\u5904\u53ea\u662f\u7c4d\u6b64\u9700\u6c42\u6f14\u793a\u5404\u79cd\u6a21\u677f\u6280\u672f\uff0c\u4f5c\u4e3a\u72ec\u7acb\u7684\u4f8b\u5b50\u7406\u89e3\u5373\u53ef\u3002<\/p>\n<p>\u53e6\u5916\uff0c\u6a21\u677f\u548c\u5b8f\u7684\u4ee3\u7801\u751f\u6210\u673a\u5236\u4e0d\u540c\uff0c\u6a21\u677f\u65e0\u6cd5\u76f4\u63a5\u751f\u6210\u539f\u751f\u7684\u7d22\u5f15\uff0c\u4f8b\u5982\u4e0a\u4e00\u7ae0\u4e2d <code class=\"\" data-line=\"\">GMP_MAKE_INDEX_SEQUENCE(2)<\/code> \u53ef\u4ee5\u751f\u6210 <code class=\"\" data-line=\"\">0, 1<\/code>\uff0c\u800c\u6a21\u677f\u53c2\u6570\u9700\u8981\u4f9d\u9644\u4e8e\u53d8\u91cf\u3001\u51fd\u6570\u6216\u7c7b\uff0c\u6807\u51c6\u91cc\u9762\u8fd9\u4e2a\u7c7b\u547d\u540d\u4e3a <code class=\"\" data-line=\"\">index_sequence<\/code>\uff0c\u4e8e\u662f\u5bf9\u5e94\u7684\u751f\u6210\u7ed3\u679c\u4fbf\u4e3a <code class=\"\" data-line=\"\">index_sequence&lt;0, 1&gt;<\/code>\u3002<\/p>\n<p>\u5728\u5b9e\u73b0 <code class=\"\" data-line=\"\">make_index_sequence<\/code> \u4e4b\u524d\uff0c\u5148\u5b9a\u4e49 <code class=\"\" data-line=\"\">index_sequence<\/code>\u3002\u4ee3\u7801\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;size_t... Is&gt; struct index_sequence {};\n\ntemplate&lt;size_t... Is&gt;\nvoid print(index_sequence&lt;Is...&gt;) {\n    (std::cout &lt;&lt; Is &lt;&lt; &quot; &quot;, ...);\n    std::cout &lt;&lt; &quot;\\n&quot;;\n}\n\nint main() {\n    \/\/ Output: 0 1 2\n    print(index_sequence&lt;0, 1, 2&gt;{});\n}<\/code><\/pre>\n<p>\u6b64\u5904\u53ea\u662f\u5229\u7528\u53ef\u53d8\u6a21\u677f\u53c2\u6570\uff0c\u65e0\u987b\u7d6e\u70e6\u3002\u4f46\u8981\u6ce8\u610f\uff0c<code class=\"\" data-line=\"\">make_index_sequence<\/code> \u5b9e\u73b0\u65b9\u5f0f\u4e0d\u540c\uff0c<code class=\"\" data-line=\"\">index_sequence<\/code> \u7684\u5b9e\u73b0\u53ef\u80fd\u4e5f\u9700\u8981\u5fae\u8c03\uff0c\u589e\u52a0\u4e00\u4e9b\u62bd\u8c61\u3002\u540e\u7eed\u5c0f\u8282\uff0c\u6709\u5dee\u5f02\u65f6\u4f1a\u660e\u786e\u5199\u51fa\uff0c\u65e0\u5dee\u5f02\u65f6\u5373\u4e3a\u6b64\u9ed8\u8ba4\u5b9e\u73b0\u3002<\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E4%BB%A5%E6%A8%A1%E6%9D%BF%E5%81%8F%E7%89%B9%E5%8C%96%E5%AE%9E%E7%8E%B0_make_index_sequence\"><\/span>\u4ee5\u6a21\u677f\u504f\u7279\u5316\u5b9e\u73b0 make_index_sequence<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u7b2c\u4e00\u79cd\u65b9\u5f0f\u91c7\u7528\u6a21\u677f\u504f\u7279\u5316\uff0c\u4f5c\u4e3a\u6700\u7ecf\u5178\u7684\u6a21\u677f\u7279\u6027\uff0c\u66b4\u9732\u6838\u5fc3\u7528\u6cd5\u3002<\/p>\n<p>\u5b8c\u6574\u5b9e\u73b0\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;size_t N, bool, size_t...&gt; struct make_index_sequence_helper {};\n\ntemplate&lt;size_t N, size_t... Is&gt;\nstruct make_index_sequence_helper&lt;N, false, Is...&gt; {\n    using type = index_sequence&lt;Is...&gt;;\n};\n\ntemplate&lt;size_t N, size_t... Is&gt;\nstruct make_index_sequence_helper&lt;N, true, Is...&gt; {\n    using type = typename make_index_sequence_helper&lt;N - 1, 0 &lt; N - 1, Is..., sizeof...(Is)&gt;::type;\n};\n\ntemplate&lt;size_t N&gt;\nusing make_index_sequence = typename make_index_sequence_helper&lt;N, 0 &lt; N&gt;::type;<\/code><\/pre>\n<p>\u8fd9\u4e2a\u5b9e\u73b0\u5f15\u51fa\u4e86\u4e00\u4e2a\u5173\u952e\u7684\u6a21\u677f\u6280\u672f\uff0c\u5982\u4f55\u52a8\u6001\u4ea7\u751f\u53ef\u53d8\u6a21\u677f\u53c2\u6570\uff1f<\/p>\n<p>\u4e00\u822c\u6765\u8bf4\uff0c\u53ef\u53d8\u6a21\u677f\u53c2\u6570\u7531\u7528\u6237\u4f20\u5165\uff0c\u800c <code class=\"\" data-line=\"\">make_index_sequence&lt;N&gt;<\/code> \u672c\u8eab\u5c31\u662f\u907f\u514d\u7528\u6237\u4f20\u5165\u53ef\u53d8\u7684\u53c2\u6570\uff0c\u53d6\u800c\u4ee3\u4e4b\u7684\u662f\u4e00\u4e2a\u7f16\u8bd1\u671f\u5e38\u91cf\u3002\u600e\u6837\u4ece\u65e0\u5230\u6709\u4ea7\u751f\u53ef\u53d8\u6a21\u677f\u53c2\u6570\uff0c\u662f\u4e00\u4e2a\u6838\u5fc3\u6280\u672f\uff0c\u76f4\u63a5\u5173\u7cfb\u5230\u7f16\u8bd1\u671f\u8fed\u4ee3\u6280\u672f\u3002<\/p>\n<p>\u5f53\u524d\u7684\u6a21\u677f\u4e0d\u652f\u6301\u81ea\u4e0b\u800c\u4e0a\u8fed\u4ee3\uff0c\u53ea\u5141\u8bb8\u81ea\u4e0a\u800c\u4e0b\u9012\u5f52\u3002\u56e0\u6b64\uff0c\u9012\u5f52\u662f\u5e94\u5bf9\u52a8\u6001\u4ea7\u751f\u5f0f\u95ee\u9898\u7684\u6839\u672c\u601d\u7ef4\u3002\u9012\u5f52\u5b58\u5728\u4e24\u4e2a\u5173\u952e\u70b9\uff0c\u4e00\u662f\u7ed3\u675f\u6761\u4ef6\uff0c\u4e8c\u662f\u94fe\u63a5\u5173\u7cfb\u3002\u903b\u8f91\u88ab\u62c6\u6210\u4e24\u4e2a\u5206\u652f\uff0c\u7ed3\u675f\u4e3a <code class=\"\" data-line=\"\">false<\/code>\uff0c\u672a\u7ed3\u675f\u4e3a <code class=\"\" data-line=\"\">true<\/code>\uff0c\u8fd9\u6b63\u662f\u9700\u8981\u4f7f\u7528\u6a21\u677f\u504f\u7279\u5316\u7684\u539f\u56e0\u3002\u7ed3\u675f\u6761\u4ef6\u5f88\u7b80\u5355\uff0c\u751f\u6210\u6700\u7ec8\u7684 <code class=\"\" data-line=\"\">index_sequence<\/code>\uff0c\u4e3b\u8981\u903b\u8f91\u5904\u7406\u5728\u94fe\u63a5\u5173\u7cfb\u8fd9\u4e2a\u5206\u652f\u3002\u94fe\u63a5\u5173\u7cfb\u903b\u8f91\u5206\u652f\u4e2d\uff0c\u6bcf\u6b21 <code class=\"\" data-line=\"\">N<\/code> \u51cf\u4e00\u7684\u540c\u65f6\uff0c\u53ef\u53d8\u6a21\u677f\u53c2\u6570\u589e\u52a0\u4e00\uff0c\u600e\u4e48\u589e\u52a0\uff1f\u4fbf\u9700\u8981\u501f\u52a9 <code class=\"\" data-line=\"\">sizeof...(Is)<\/code>\uff0c\u5b83\u53ef\u4ee5\u8ba1\u7b97\u53ef\u53d8\u6a21\u677f\u53c2\u6570\u6570\u91cf\uff0c\u8fd9\u4e2a\u6570\u91cf\u6b63\u597d\u4e0e\u7d22\u5f15\u503c\u5bf9\u5e94\u3002\u521d\u59cb\u60c5\u51b5\u4e0b\uff0c\u4e0d\u5b58\u5728\u53ef\u53d8\u6a21\u677f\u53c2\u6570\uff0c\u4e8e\u662f <code class=\"\" data-line=\"\">sizeof...(Is)<\/code> \u4ea7\u751f <code class=\"\" data-line=\"\">0<\/code>\uff0c\u6bcf\u9012\u5f52\u4e00\u6b21\uff0c\u53ef\u53d8\u6a21\u677f\u53c2\u6570\u52a0\u4e00\uff0c\u76f4\u81f3 <code class=\"\" data-line=\"\">N<\/code> \u7b49\u4e8e 0\uff0c\u6b65\u5165\u7ed3\u675f\u6761\u4ef6\u3002<\/p>\n<p>\u6d4b\u8bd5\u4ee3\u7801\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">int main() {\n    \/\/ Output: 0 1 2 3 4\n    print(make_index_sequence&lt;5&gt;{});\n}<\/code><\/pre>\n<h3><span class=\"ez-toc-section\" id=\"%E4%BB%A5_constexpr_if_%E5%AE%9E%E7%8E%B0_make_index_sequence\"><\/span>\u4ee5 constexpr if \u5b9e\u73b0 make_index_sequence<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u7b2c\u4e8c\u79cd\u65b9\u5f0f\u91c7\u7528 C++17 <code class=\"\" data-line=\"\">constexpr if<\/code>\uff0c\u4e24\u4e2a\u5206\u652f\u4e0d\u9700\u518d\u501f\u52a9\u504f\u7279\u5316\u6a21\u677f\uff0c\u6781\u5927\u964d\u4f4e\u4ee3\u7801\u91cd\u590d\u6027\uff0c\u6d41\u7a0b\u8fd1\u4f3c\u52a8\u6001\u6761\u4ef6\u5206\u652f\uff0c\u4ee3\u7801\u66f4\u52a0\u7b80\u6d01\u3001\u6613\u4e8e\u7406\u89e3\u3002<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;size_t N, size_t... Is&gt;\nconstexpr auto make_index_sequence() {\n    if constexpr (sizeof...(Is) &lt; N)\n        return make_index_sequence&lt;N, Is..., sizeof...(Is)&gt;();\n    else\n        return index_sequence&lt;Is...&gt;{};\n}<\/code><\/pre>\n<p>\u89e3\u6cd5\u601d\u8def\uff0c\u8868\u8fc7\u4e0d\u9898\u3002\u4e14\u8bf4\u4e24\u79cd\u65b9\u5f0f\u7684\u533a\u522b\uff0c\u6a21\u677f\u504f\u7279\u5316\u91c7\u7528\u7684\u662f\u7c7b\u6a21\u677f\uff0c\u800c <code class=\"\" data-line=\"\">constexpr if<\/code> \u91c7\u7528\u7684\u662f\u51fd\u6570\u6a21\u677f\uff0c\u7531\u662f\u4e00\u4e2a\u8fd4\u56de\u7684\u662f\u7c7b\u578b\uff0c\u4e00\u4e2a\u8fd4\u56de\u7684\u662f\u7f16\u8bd1\u671f\u5e38\u91cf\u503c\u3002<\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E4%BB%A5%E9%80%92%E5%BD%92_Lambda_%E5%AE%9E%E7%8E%B0_make_index_sequence\"><\/span>\u4ee5\u9012\u5f52 Lambda \u5b9e\u73b0 make_index_sequence<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u7b2c\u4e09\u79cd\u65b9\u5f0f\u91c7\u7528 C++23 Recursive Lambda\uff0c\u65e0\u975e\u662f\u7b2c\u4e8c\u79cd\u65b9\u5f0f\u7684\u53e6\u4e00\u79cd\u8868\u73b0\u5f62\u5f0f\u3002<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">constexpr auto make_index_sequence = []&lt;size_t N, size_t... Is&gt;(this auto self) {\n    if constexpr (sizeof...(Is) &lt; N)\n        return self.template operator()&lt;N, Is..., sizeof...(Is)&gt;();\n    else\n        return index_sequence&lt;Is...&gt;{};\n};\n\nprint(make_index_sequence.template operator()&lt;5&gt;());<\/code><\/pre>\n<p>Template Lambda \u662f C++20 \u52a0\u5165\u7684\u7279\u6027\uff0c\u8c03\u7528\u7684\u5176\u5b9e\u662f <code class=\"\" data-line=\"\">template&lt;size_t N, size_t... Is&gt; operator()<\/code>\uff0c\u662f\u4ee5\u5fc5\u987b\u4f7f\u7528\u8fd9\u79cd\u5947\u602a\u7684\u8bed\u6cd5\u6765\u4f20\u9012\u53c2\u6570\u3002<\/p>\n<p>\u82e5\u60f3\u907f\u514d\u8fd9\u79cd\u8bed\u6cd5\uff0c\u53ef\u4ee5\u4e3a Lambda \u589e\u52a0\u4e00\u4e2a <code class=\"\" data-line=\"\">int_constant<\/code> \u53c2\u6570\uff0c\u7528\u6cd5\u53d8\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;size_t...&gt; struct int_constant {};\n\nconstexpr auto make_index_sequence = []&lt;size_t N, size_t... Is&gt;\n    (this auto self, int_constant&lt;N, Is...&gt;) {\n        if constexpr (sizeof...(Is) &lt; N)\n            return self(int_constant&lt;N, Is..., sizeof...(Is)&gt;{});\n        else\n            return index_sequence&lt;Is...&gt;{};\n};\n\nprint(make_index_sequence(int_constant&lt;5&gt;{}));<\/code><\/pre>\n<p>\u8f83\u4e8e\u524d\u8005\uff0c\u6b64\u6cd5\u7565\u5fae\u7b80\u5316\u4e86\u4e00\u4e9b\u7528\u6cd5\uff0c\u4f46\u4ecd\u9ebb\u70e6\u3002\u66f4\u52a0\u7cbe\u5999\u7684\u4e00\u79cd\u65b9\u5f0f\u662f\u7ec4\u5408\u6cdb\u578b Lambda \u548c\u53d8\u91cf\u6a21\u677f\uff0c\u6dfb\u4e0a\u7c7b\u578b\u80fd\u529b\u3002\u4e8e\u662f\uff0c\u53ef\u4ee5\u50cf\u524d\u9762\u4e24\u79cd\u5b9e\u73b0\u65b9\u5f0f\u90a3\u822c\u4f7f\u7528\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;size_t N&gt;\ninline constexpr auto make_index_sequence = []&lt;size_t... Is&gt;(this auto self) {\n    if constexpr (sizeof...(Is) &lt; N)\n        return self.template operator()&lt;Is..., sizeof...(Is)&gt;();\n    else\n        return index_sequence&lt;Is...&gt;{};\n};\n\nprint(make_index_sequence&lt;5&gt;());<\/code><\/pre>\n<p>\u8fd9\u79cd\u65b9\u5f0f\u548c\u7b2c\u4e8c\u79cd\u65b9\u5f0f <code class=\"\" data-line=\"\">constexpr if<\/code> \u540c\u6e90\uff0c\u8fd4\u56de\u7684\u4f9d\u65e7\u662f\u4e00\u4e2a\u7f16\u8bd1\u671f\u5e38\u91cf\u503c\u3002<\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E4%BB%A5%E6%A0%87%E7%AD%BE%E5%88%86%E5%8F%91%E5%AE%9E%E7%8E%B0_make_index_sequence\"><\/span>\u4ee5\u6807\u7b7e\u5206\u53d1\u5b9e\u73b0 make_index_sequence<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u7b2c\u56db\u79cd\u65b9\u5f0f\u91c7\u7528\u6807\u7b7e\u5206\u53d1\uff0c\u672c\u8d28\u662f\u5229\u7528\u6807\u7b7e\u533a\u5206\u51fd\u6570\u91cd\u8f7d\uff0c\u9009\u62e9\u4e0d\u540c\u7684\u5206\u652f\uff0c\u662f\u65e9\u671f\u7684\u4e00\u79cd\u6a21\u677f\u6280\u672f\u3002<\/p>\n<p>\u5b8c\u6574\u5b9e\u73b0\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;size_t N, size_t... Is&gt;\nconstexpr auto make_index_sequence_impl(std::false_type) {\n    return index_sequence&lt;Is...&gt;{};\n}\n\ntemplate&lt;size_t N, size_t... Is&gt;\nconstexpr auto make_index_sequence_impl(std::true_type) {\n    return make_index_sequence_impl&lt;N, Is..., sizeof...(Is)&gt;(\n        std::bool_constant&lt;sizeof...(Is) + 1 &lt; N&gt;{});\n}\n\ntemplate&lt;size_t N&gt;\nconstexpr auto make_index_sequence() {\n    return make_index_sequence_impl&lt;N&gt;(std::bool_constant&lt;0 &lt; N&gt;{});\n}<\/code><\/pre>\n<p>\u8fd9\u91cc\u76f4\u63a5\u501f\u52a9\u6807\u51c6\u4e2d\u7684\u5df2\u6709\u6807\u7b7e <code class=\"\" data-line=\"\">std::false_type<\/code> \u548c <code class=\"\" data-line=\"\">std::true_type<\/code> \u5b9e\u73b0\u5206\u53d1\uff0c\u5206\u522b\u5bf9\u5e94\u4e24\u4e2a\u903b\u8f91\u5206\u652f\uff0c\u5b9e\u73b0\u9012\u5f52\u3002<code class=\"\" data-line=\"\">std::bool_constant<\/code> \u80fd\u591f\u751f\u6210\u8fd9\u4e24\u4e2a\u6807\u7b7e\uff0c\u4ece\u800c\u5b8c\u6210\u5b9e\u9645\u5206\u53d1\u3002<\/p>\n<p>\u6b64\u6cd5\u4e0e\u6a21\u677f\u504f\u7279\u5316\u76f8\u4f3c\uff0c\u4f46\u672c\u8d28\u4e0a\u5c5e\u4e8e\u4e0d\u540c\u7684\u591a\u6001\u8868\u73b0\u65b9\u5f0f\u3002<\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E4%B8%80%E7%A7%8D%E6%9B%B4%E5%BF%AB%E7%9A%84_make_index_sequence_%E5%AE%9E%E7%8E%B0%E6%B3%95\"><\/span>\u4e00\u79cd\u66f4\u5feb\u7684 make_index_sequence \u5b9e\u73b0\u6cd5<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u672c\u8282\u4ecb\u7ecd\u4e00\u79cd $$O(\\log N)$$ \u590d\u6742\u5ea6\u7684\u5b9e\u73b0\uff0c\u6765\u81ea <a href=\"https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/stackoverflow.com\/a\/17426611\/19868918\">https:\/\/blue-sea-697d.quartiers047.workers.dev:443\/https\/stackoverflow.com\/a\/17426611\/19868918<\/a> \uff0c\u7f16\u8bd1\u901f\u5ea6\u66f4\u5feb\uff0c\u4f46\u76f8\u5e94\u5730\uff0c\u4e5f\u66f4\u590d\u6742\u3002<\/p>\n<p>\u5b8c\u6574\u5b9e\u73b0\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;size_t... Is&gt; struct index_sequence {\n    using type = index_sequence;\n};\n\ntemplate&lt;class, class&gt; struct merge_index_sequence {};\n\ntemplate&lt;size_t... LIs, size_t... RIs&gt;\nstruct merge_index_sequence&lt;index_sequence&lt;LIs...&gt;, index_sequence&lt;RIs...&gt;&gt;\n    : index_sequence&lt;LIs..., (sizeof...(LIs) + RIs)...&gt;\n{};\n\ntemplate&lt;size_t N&gt;\nstruct make_index_sequence : merge_index_sequence&lt;\n        typename make_index_sequence&lt;N \/ 2&gt;::type,\n        typename make_index_sequence&lt;N - N \/ 2&gt;::type\n    &gt;\n{};\n\ntemplate&lt;&gt; struct make_index_sequence&lt;0&gt; : index_sequence&lt;&gt; {};\ntemplate&lt;&gt; struct make_index_sequence&lt;1&gt; : index_sequence&lt;0&gt; {};<\/code><\/pre>\n<p>\u8fd9\u662f\u4e00\u79cd\u4e0e\u9012\u5f52\u7ee7\u627f\u76f8\u4f3c\u7684\u5b9e\u73b0\u601d\u8def\uff0c\u524d\u9762\u7684\u5b9e\u73b0\u601d\u8def\u90fd\u662f\u7ebf\u6027\u9012\u589e\uff0c\u800c\u8fd9\u79cd\u601d\u8def\u6bcf\u6b21\u4f1a\u6298\u534a\u5b9e\u4f8b\u5316\uff0c\u76f4\u63a5\u628a\u5b9e\u73b0\u5316\u6df1\u5ea6\u4ece $$O(N)$$ \u964d\u4f4e\u5230 $$O(\\log N)$$\u3002\u6838\u5fc3\u601d\u8def\u5e76\u65e0\u53d8\u5316\uff0c\u4f9d\u65e7\u662f\u9012\u5f52\uff0c\u5229\u7528 <code class=\"\" data-line=\"\">sizeof...(Is)<\/code> \u9010\u6b21\u589e\u52a0\u6a21\u677f\u53c2\u6570\u3002\u53d8\u5316\u4e3b\u8981\u5728\u4e8e\u6298\u534a\u5b9e\u4f8b\u5316\u4e0e\u5408\u5e76\uff0c\u95ee\u9898\u88ab\u62c6\u5206\u5f97\u66f4\u5c0f\u3002<\/p>\n<p>\u4ee5 N \u53d6 5 \u4e3a\u4f8b\uff0c\u6b64\u65f6\u88ab\u62c6\u5206\u6210\u6c42 2 \u548c 3\uff0c\u4ee3\u7801\u8868\u793a\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">merge_index_sequence&lt;make_index_sequence&lt;2&gt;, make_index_sequence&lt;3&gt;&gt;\n\u2191\nmake_index_sequence&lt;5&gt;<\/code><\/pre>\n<p>\u8fd9\u662f\u7b2c\u4e00\u5c42\u6df1\u5ea6\uff0c\u95ee\u9898\u8f6c\u6362\u6210\u6c42 <code class=\"\" data-line=\"\">make_index_sequence&lt;2&gt;<\/code> \u548c <code class=\"\" data-line=\"\">make_index_sequence&lt;3&gt;<\/code>\u3002<\/p>\n<p>\u5148\u770b <code class=\"\" data-line=\"\">make_index_sequence&lt;2&gt;<\/code>\uff0c\u53c8\u88ab\u62c6\u5206\u6210\u6c42 1 \u548c 2\uff0c\u4ee3\u7801\u8868\u793a\u4e3a\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">merge_index_sequence&lt;make_index_sequence&lt;1&gt;, make_index_sequence&lt;0&gt;&gt;\n\u2191\nmake_index_sequence&lt;2&gt;<\/code><\/pre>\n<p>\u5230\u6b64\u65f6\u5c31\u4e0d\u80fd\u518d\u62c6\u5206\uff0c\u5426\u5219 <code class=\"\" data-line=\"\">1 - 1\/2<\/code> \u5c06\u9020\u6210\u6b7b\u5faa\u73af\uff0c\u4ee5\u662f <code class=\"\" data-line=\"\">make_index_sequence&lt;1&gt;<\/code> \u548c <code class=\"\" data-line=\"\">make_index_sequence&lt;0&gt;<\/code> \u7279\u5316\u4f5c\u4e3a\u7ed3\u675f\u6761\u4ef6\uff0c<code class=\"\" data-line=\"\">make_index_sequence&lt;2&gt;<\/code> \u6700\u7ec8\u751f\u6210\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">index_sequence&lt;0, 1&gt;\n\u2191\nmake_index_sequence&lt;2&gt;<\/code><\/pre>\n<p>\u53d6 <code class=\"\" data-line=\"\">type<\/code>\uff0c\u5373\u4e3a <code class=\"\" data-line=\"\">index_sequence&lt;0, 1&gt;<\/code>\u3002<\/p>\n<p>\u518d\u770b <code class=\"\" data-line=\"\">make_index_sequence&lt;3&gt;<\/code>\uff0c\u88ab\u62c6\u5206\u6210 1 \u548c 2\uff0c\u4ee3\u7801\u8868\u793a\u4e3a\uff1a<\/p>\n<pre><code class=\"\" data-line=\"\">merge_index_sequence&lt;make_index_sequence&lt;1&gt;, make_index_sequence&lt;2&gt;&gt;\n\u2191\nmake_index_sequence&lt;3&gt;<\/code><\/pre>\n<p>\u540c\u7406\u53ef\u5f97\uff0c\u6700\u7ec8\u751f\u6210 <code class=\"\" data-line=\"\">index_sequence&lt;0, 1, 2&gt;<\/code>\u3002<\/p>\n<p>\u4ee5\u4e0a\u662f\u7b2c\u4e8c\u5c42\u6df1\u5ea6\uff0c\u95ee\u9898\u62c6\u5206\u4fbf\u5df2\u89e3\u51b3\uff0c\u81f3\u6b64\u5408\u5e76\u7ed3\u675f\u3002\u5229\u7528 <code class=\"\" data-line=\"\">merge_index_sequence<\/code> \u5408\u5e76 <code class=\"\" data-line=\"\">index_sequence&lt;0, 1&gt;<\/code> \u548c <code class=\"\" data-line=\"\">index_sequence&lt;0, 1, 2&gt;<\/code>\uff0c\u6700\u7ec8\u5f97\u5230 <code class=\"\" data-line=\"\">index_sequence&lt;0, 1, 2, 3, 4&gt;<\/code>\uff0c\u95ee\u9898\u89e3\u51b3\u3002<\/p>\n<p>\u6ce8\u610f\uff0c\u524d\u6587\u63d0\u5230\u8fd9\u79cd\u601d\u8def\u4e0e\u9012\u5f52\u7ee7\u627f\u76f8\u4f3c\uff0c\u4f46\u5176\u5e76\u975e\u9012\u5f52\u7ee7\u627f\uff0c\u53ea\u662f\u9012\u5f52\u5b9e\u4f8b\u5316\u7684\u4e00\u79cd\u5f62\u5f0f\uff0c\u8fdc\u65e0\u9012\u5f52\u7ee7\u627f\u590d\u6742\u3002<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E7%B1%BB%E5%9E%8B%E8%90%83%E5%8F%96\"><\/span>\u7c7b\u578b\u8403\u53d6<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u7c7b\u578b\u8403\u53d6\u5c31\u662f\u4ece\u5df2\u6709\u6a21\u677f\u7c7b\u578b\u4e2d\u63d0\u53d6\u4fe1\u606f\u7684\u65b9\u6cd5\uff0c\u662f\u6a21\u677f\u7684\u6838\u5fc3\u6280\u672f\u4e4b\u4e00\u3002<\/p>\n<p>\u4ee5 <code class=\"\" data-line=\"\">std::function<\/code> \u4e3a\u4f8b\uff0c\u5982\u4f55\u8403\u53d6\u6a21\u677f\u53c2\u6570\u7684\u57fa\u672c\u4fe1\u606f\uff1f\u6574\u4f53\u601d\u8def\u662f\u589e\u52a0\u95f4\u63a5\u5c42\uff0c\u5c06\u60f3\u8981\u7684\u53c2\u6570\u91cd\u65b0\u5199\u5230\u6a21\u677f\u5934\u3002<\/p>\n<p>\u5b9e\u73b0\u4e00\u4e2a <code class=\"\" data-line=\"\">function_traits<\/code> \u8403\u53d6\u4fe1\u606f\uff0c\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;typename T&gt;\nstruct function_traits;\n\ntemplate&lt;typename R, typename... Args&gt;\nstruct function_traits&lt;std::function&lt;R(Args...)&gt;&gt;\n{\n    static constexpr std::size_t size = sizeof...(Args);\n    using result_type = R;\n\n    template&lt;size_t I&gt;\n    struct get {\n        using type = typename std::tuple_element&lt;I, std::tuple&lt;Args...&gt;&gt;::type;\n    };\n};<\/code><\/pre>\n<p>\u8fd9\u4e2a\u5de5\u5177\u80fd\u591f\u8403\u53d6 <code class=\"\" data-line=\"\">std::function<\/code> \u7684\u53c2\u6570\u4e2a\u6570\u3001\u8fd4\u56de\u7c7b\u578b\u53ca\u6307\u5b9a\u4f4d\u53c2\u6570\u7c7b\u578b\u3002\u4f7f\u7528\u793a\u4f8b\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt;class F, size_t I&gt;\nvoid print_ith_type() {\n    std::cout &lt;&lt; typeid(typename function_traits&lt;F&gt;::get&lt;I&gt;::type).name() &lt;&lt; &quot;\\n&quot;;\n};\n\nint main() {\n    using FuncType = std::function&lt;void(int, double, std::string)&gt;;\n\n    std::cout &lt;&lt; &quot;size of template parameter list: &quot; &lt;&lt; function_traits&lt;FuncType&gt;::size &lt;&lt; &quot;\\n&quot;;\n    std::cout &lt;&lt; typeid(function_traits&lt;FuncType&gt;::result_type).name() &lt;&lt; &quot;\\n&quot;;\n\n    print_ith_type&lt;FuncType, 0&gt;();\n    print_ith_type&lt;FuncType, 1&gt;();\n    print_ith_type&lt;FuncType, 2&gt;();\n}<\/code><\/pre>\n<p>\u5f53\u7136\u53ef\u4ee5\u8fdb\u4e00\u6b65\u7b80\u5316\u5b8c\u5584\uff0c\u6b64\u5904\u53ea\u5c55\u793a\u8fd9\u79cd\u65b9\u5f0f\uff0c\u4e0d\u7ec6\u4f5c\u8868\u3002<\/p>\n<p>\u4f46\u4e5f\u6709\u67d0\u4e9b\u7279\u6b8a\u7684\uff0c\u4ee5 <code class=\"\" data-line=\"\">is_member_function_pointer<\/code> \u7684\u4e00\u79cd\u5b9e\u73b0\u65b9\u5f0f\u4e3a\u4f8b\uff1a<\/p>\n<pre><code class=\"language-cpp\" data-line=\"\">template&lt; class T &gt;\nstruct is_member_function_pointer_helper : std::false_type {};\n\ntemplate&lt; class T, class U&gt;\nstruct is_member_function_pointer_helper&lt;T U::*&gt; : std::is_function&lt;T&gt; {};\n\ntemplate&lt; class T &gt;\nstruct is_member_function_pointer : is_member_function_pointer_helper&lt; std::remove_cv_t&lt;T&gt; &gt; {};<\/code><\/pre>\n<p>\u6ce8\u610f\u8fd9\u91cc\u7684 <code class=\"\" data-line=\"\">&lt;T U::*&gt;<\/code>\uff0c<code class=\"\" data-line=\"\">T<\/code> \u548c <code class=\"\" data-line=\"\">U::*<\/code> \u5206\u522b\u5bf9\u5e94\u54ea\u90e8\u5206\u7c7b\u578b\uff1f\u5018\u82e5\u6210\u5458\u51fd\u6570\u4e3a <code class=\"\" data-line=\"\">void A::foo()<\/code>\uff0c\u6b64\u65f6 <code class=\"\" data-line=\"\">T<\/code> \u5bf9\u5e94 <code class=\"\" data-line=\"\">void()<\/code>\uff0c<code class=\"\" data-line=\"\">U::*<\/code> \u5bf9\u5e94 <code class=\"\" data-line=\"\">A::foo<\/code>\u3002<\/p>\n<p>\u7c7b\u578b\u8403\u53d6\u5728\u6a21\u677f\u5143\u7f16\u7a0b\u4e2d\uff0c\u5e76\u4e0d\u7b97\u96be\uff0c\u4e0d\u518d\u591a\u8bba\u3002<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E6%80%BB%E7%BB%93\"><\/span>\u603b\u7ed3<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u672c\u7ae0\u6df1\u5165\u56de\u987e\u4e86\u6a21\u677f\u6d89\u53ca\u7684\u6838\u5fc3\u7406\u8bba\u548c\u6280\u672f\uff0c\u662f\u4ea7\u751f\u5f0f\u6a21\u677f\u5143\u7f16\u7a0b\u7684\u57fa\u672c\u77e5\u8bc6\u3002<\/p>\n<p>\u6a21\u677f\u6240\u5e26\u6765\u7684\u6cdb\u578b\u601d\u7ef4\u3001\u6a21\u677f\u53c2\u6570\u3001\u6a21\u677f\u7c7b\u578b\u3001\u6a21\u677f\u5b9e\u4f8b\u5316\u3001\u7c7b\u578b\u8403\u53d6\u662f\u5176\u4e2d\u7684\u6838\u5fc3\uff0c\u518d\u9ad8\u6df1\u7684\u6a21\u677f\u6280\u672f\uff0c\u4e5f\u4ee5\u6b64\u4e3a\u57fa\u77f3\u3002<\/p>\n<p>\u67d0\u4e9b\u6982\u5ff5\u8ba8\u8bba\u5f97\u97ad\u8f9f\u5165\u91cc\uff0c\u6bd4\u8f83\u6df1\u523b\uff0c\u5373\u4fbf\u662f\u6a21\u677f\u4e66\u7c4d\u4e2d\u4ea6\u672a\u6d89\u53ca\uff0c\u6709\u4e00\u5b9a\u96be\u5ea6\uff0c\u4f46\u5bf9\u4e8e\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\u6765\u8bf4\uff0c\u5f88\u662f\u5fc5\u8981\u3002<\/p>\n<p>\u540e\u7eed\u7ae0\u8282\uff0c\u5c06\u5229\u7528\u8fd9\u4e9b\u6280\u672f\u5b9e\u73b0\u4ee3\u7801\u751f\u6210\uff0c\u7f16\u5199\u5f3a\u5927\u7684\u5de5\u5177\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u524d\u8a00 \u672c\u7cfb\u5217\u5206\u4e3a\u4e0a\u4e2d\u4e0b\u4e09\u4e2a\u7bc7\u7ae0\uff0c\u524d\u56db\u7ae0\u4f5c\u4e3a\u4e0a\u7bc7\uff0c\u8be6\u7ec6\u4ecb\u7ecd\u4e86\u5b8f\u5728\u4ea7\u751f\u5f0f\u7f16\u7a0b\u4e2d\u7684\u539f\u7406\u548c\u5e94\u7528\uff0c\u672c\u7ae0\u5f00\u59cb\u6b65\u5165\u4e2d\u7bc7\uff0c\u6b63\u5f0f\u8fdb\u5165 C++ \u7684\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\u6280\u672f\u3002 \u5b8f\u662f C \u65f6\u671f\u7684\u4ea7\u7269\uff0c\u529f\u80fd\u9887\u4e3a\u7b80\u964b\uff0c\u4ea6\u975e\u56fe\u7075\u5b8c\u5907\uff0c\u5373\u6216\u8bf8\u822c\u5947\u6280\u5999\u8bc0\u52a0\u8eab\uff0c\u9650\u5236\u4ecd\u591a\u3002\u4e14\u8c03\u8bd5\u4e0d\u6613\uff0c\u6709\u6240\u675f\u7f1a\uff0c\u4ee5\u662f\u4ec5\u4f5c\u8f85\u52a9\uff0c\u7528\u6765\u5b9e\u73b0\u7b80\u5355\u7684\u4ee3\u7801\u751f\u6210\u529f\u80fd\u3002\u81f3 C++ \u65f6\u671f\uff0c\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\u5de5\u5177\u9661\u589e\uff0c\u5176\u4e2d\u4ee5\u6a21\u677f\u4e3a\u4e00\u5207\u7684\u6839\u57fa\uff0c\u53d1\u679d\u6563\u53f6\uff0c\u5c14\u4eca\u6b63\u5411\u9759\u6001\u53cd\u5c04\u524d\u8fdb\u3002 \u672c\u7ae0\u6d89\u53ca\u4e0d\u8ba1\u5176\u6570\u7684\u6a21\u677f\u6280\u672f\uff0c\u4e3b\u8981\u96c6\u4e2d\u4e8e\u6a21\u677f\u7684\u6838\u5fc3\u7406\u8bba\u548c\u7528\u6cd5\uff0c\u6982\u5ff5\u9519\u7efc\u590d\u6742\uff0c\u6280\u672f\u5c42\u51fa\u4e0d\u7a77\u3002\u96be\u5ea6\u7b49\u7ea7\u7edd\u5bf9\u4e0d\u4f4e\uff0c\u662f\u672c\u7cfb\u5217\u4e2d\u975e\u5e38\u91cd\u8981\u7684\u4e00\u7ae0\u3002 \u7eb5\u7136\u67d0\u4e9b\u6982\u5ff5\u548c\u6280\u672f\u4f60\u5df2\u77e5\u6089\uff0c\u4e5f\u83ab\u8981\u8df3\u8fc7\u67d0\u4e2a\u5c0f\u8282\uff0c\u56e0\u4e3a\u672c\u7cfb\u5217\u7684\u91cd\u5fc3\u4e0d\u5728\u6a21\u677f\u7f16\u7a0b\uff0c\u800c\u5728\u4ea7\u751f\u5f0f\u7f16\u7a0b\uff0c\u8bba\u8ff0\u89d2\u5ea6\u5c06\u6709\u6240\u5dee\u5f02\u3002 \u6cdb\u578b\u2026\u2026\u5143\u7f16\u7a0b \u4f20\u7edf\u8fc7\u7a0b\u5f0f\u7f16\u7a0b\u7684\u601d\u8def\u662f\u5c06\u903b\u8f91\u4f5c\u4e3a\u51fd\u6570\uff0c\u6570\u636e\u4f5c\u4e3a\u51fd\u6570\u7684\u8f93\u5165\u548c\u8f93\u51fa\uff0c\u901a\u8fc7\u65e0\u6570\u4e2a\u51fd\u6570\u6765\u7ec4\u7ec7\u5b8c\u6574\u7684\u903b\u8f91\u9700\u6c42\uff0c\u597d\u4f3c\u642d\u79ef\u6728\uff0c\u6784\u5efa\u51fa\u5404\u79cd\u7269\u4f53\u3002 \u9762\u5411\u5bf9\u8c61\u7f16\u7a0b\u66f4\u8fdb\u4e00\u6b65\uff0c\u601d\u8def\u662f\u5c06\u903b\u8f91\u548c\u6570\u636e\u5408\u5e76\u8d77\u6765\uff0c\u6784\u6210\u4e00\u4e2a\u4e2a\u7c7b\uff0c\u7c7b\u4e2d\u5305\u542b\u5404\u79cd\u6570\u636e\u548c\u51fd\u6570\uff0c\u5916\u90e8\u53ea\u80fd\u501f\u52a9\u516c\u5f00\u51fd\u6570\u64cd\u7eb5\u8fd9\u4e9b\u6570\u636e\u3002\u8fd9\u79cd\u4ee5\u5bf9\u8c61\u8868\u793a\u73b0\u5b9e\u4e8b\u7269\u7684\u65b9\u5f0f\u4e0e\u4eba\u7684\u601d\u7ef4\u66f4\u52a0\u63a5\u8fd1\uff0c\u7b80\u5316\u4e86\u62bd\u8c61\u5316\u7684\u96be\u5ea6\u3002 \u6cdb\u578b\u7f16\u7a0b\u5219\u6b32\u5c06\u903b\u8f91\u548c\u6570\u636e\u5206\u79bb\uff0c\u5e76\u63d0\u4f9b\u4e00\u79cd\u62bd\u8c61\u5316\u6570\u636e\u7684\u65b9\u5f0f\uff0c\u4f7f\u5f97\u4e0d\u540c\u7684\u6570\u636e\u80fd\u591f\u4f7f\u7528\u540c\u4e00\u79cd\u903b\u8f91\uff0c\u6781\u5927\u964d\u4f4e\u4e86\u4ee3\u7801\u7684\u91cd\u590d\u6027\u3002\u4e8e\u662f\uff0c\u540c\u4e00\u4e2a\u51fd\u6570\u80fd\u591f\u4f20\u9012\u4e0d\u540c\u7684\u53c2\u6570\u7c7b\u578b\uff0c\u8fd9\u53eb\u51fd\u6570\u6a21\u677f\uff1b\u540c\u4e00\u4e2a\u7c7b\u80fd\u591f\u4f20\u9012\u4e0d\u540c\u7684\u6570\u636e\uff0c\u8fd9\u53eb\u7c7b\u6a21\u677f\u3002 C++ \u662f\u4e00\u79cd\u591a\u8303\u5f0f\u8bed\u8a00\uff0c\u4ee5\u6a21\u677f\u652f\u6301\u6cdb\u578b\u7f16\u7a0b\uff0c\u5141\u8bb8\u7f16\u5199\u6cdb\u578b\u7684\u51fd\u6570\u548c\u6570\u636e\uff0c\u529f\u80fd\u4e0d\u4f9d\u8d56\u4e8e\u67d0\u79cd\u5177\u4f53\u7684\u6570\u636e\u7c7b\u578b\uff0c\u4f7f\u7528 SFINAE \u548c Concepts \u7ea6\u675f\u62bd\u8c61\u5316\u7684\u7c7b\u578b\u3002\u8fd9\u79cd\u80fd\u529b\u4f7f\u5176\u652f\u6301 Parametric Polymorphism\uff0c\u5728\u591a\u6001\u7684\u9009\u62e9\u4e0a\u4e0d\u5fc5\u5c40\u9650\u4e8e\u4f20\u7edf\u7684 Subtype Polymorphism\uff0c\u53ef\u4ee5\u4f7f\u7528\u7f16\u8bd1\u671f\u591a\u6001\u66ff\u4ee3\u8fd0\u884c\u671f\u591a\u6001\u3002 C++ \u4e2d\uff0c\u5143\u7f16\u7a0b\u6307\u7684\u662f\u53d1\u751f\u4e8e\u7f16\u8bd1\u671f\u7684\u7f16\u7a0b\uff0c\u6a21\u677f\u4e3a C++ \u5e26\u6765\u6cdb\u578b\u7f16\u7a0b\u7684\u540c\u65f6\uff0c\u4e5f\u5e26\u6765\u4e86\u5143\u7f16\u7a0b\u80fd\u529b\u3002\u7531\u6a21\u677f\u5b9e\u73b0\u7684\u5143\u7f16\u7a0b\uff0c\u79f0\u4e3a\u6a21\u677f\u5143\u7f16\u7a0b\u3002\u800c\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\uff0c\u6307\u7684\u662f\u53d1\u751f\u4e8e\u7f16\u8bd1\u671f\u7684\u5bf9\u4e8e\u7f16\u7a0b\u7684\u7f16\u7a0b\uff0c\u6a21\u677f\u672c\u5c31\u652f\u6301\u5728\u7f16\u8bd1\u671f\u751f\u6210\u4ee3\u7801\uff0c\u56e0\u6b64\u6a21\u677f\u4e5f\u80fd\u591f\u5b9e\u73b0\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\u3002 \u62bd\u8c61\u5316\u3001\u5177\u4f53\u5316\u2026\u2026\u6a21\u677f \u5728\u6a21\u677f\u4e16\u754c\u4e2d\uff0c\u51fd\u6570\u4e0d\u518d\u662f\u5177\u4f53\u7684\u51fd\u6570\uff0c\u6570\u636e\u7c7b\u578b\u4e5f\u4e0d\u518d\u662f\u5177\u4f53\u7684\u6570\u636e\u7c7b\u578b\u3002\u6a21\u677f\u5b9b\u5982\u4e00\u4e2a\u6a21\u5177\uff0c\u501f\u5176\u80fd\u591f\u4ea7\u751f\u5404\u5f0f\u5404\u6837\u7684\u7269\u4f53\uff0c\u8fd9\u4e9b\u7269\u4f53\u7684\u989c\u8272\u3001\u6750\u6599\u53ef\u80fd\u4e0d\u5c3d\u76f8\u540c\uff0c\u4f46\u662f\u5f62\u72b6\u3001\u5927\u5c0f\u662f\u4e00\u81f4\u7684\u3002\u4e5f\u5c31\u662f\u8bf4\uff0c\u4e00\u7c7b\u7269\u4f53\uff0c\u5fc5\u987b\u5b58\u5728\u5171\u540c\u7684\u90e8\u5206\uff0c\u624d\u80fd\u591f\u62bd\u8c61\u51fa\u4e00\u4e2a\u6a21\u5177\uff0c\u6a21\u5177\u7684\u4f5c\u7528\u5c31\u662f\u91cd\u590d\u5229\u7528\u8fd9\u4e9b\u5171\u540c\u4e4b\u5904\uff0c\u51cf\u5c11\u91cd\u590d\u6027\u3002 \u7f16\u7a0b\u662f\u5de5\u5177\uff0c\u672c\u8d28\u662f\u89e3\u51b3\u95ee\u9898\uff0c\u89e3\u51b3\u95ee\u9898\u8003\u9a8c\u7684\u5c31\u662f\u62bd\u8c61\u5316\u548c\u5177\u4f53\u5316\u7684\u80fd\u529b\u3002\u62bd\u8c61\u5316\u5e94\u5bf9\u7684\u662f\u73b0\u5b9e\u4e16\u754c\u4e2d\u7684\u4e0d\u53d8\uff0c\u800c\u5177\u4f53\u5316\u5e94\u5bf9\u7684\u662f\u73b0\u5b9e\u4e16\u754c\u4e2d\u7684\u53d8\u5316\uff0c\u80fd\u591f\u6e05\u695a\u5730\u8ba4\u8bc6\u5230\u53d8\u4e0e\u4e0d\u53d8\u662f\u4ec0\u4e48\uff0c\u95ee\u9898\u4e5f\u5c31\u8fce\u5203\u800c\u89e3\u4e86\u3002\u90a3\u5148\u6765\u5206\u6e05\u62bd\u8c61\u5316\u548c\u5177\u4f53\u5316\u7684\u6982\u5ff5\u3002 \u62bd\u8c61\u7684\u610f\u601d\u662f\uff0c\u5728\u8bb8\u591a\u4e8b\u7269\u4e2d\uff0c\u53bb\u9664\u975e\u672c\u8d28\u7684\u5c5e\u6027\uff0c\u62bd\u51fa\u672c\u8d28\u5c5e\u6027\u3002\u62bd\u8c61\u5316\u5c31\u662f\u5448\u73b0\u51fa\u5177\u4f53\u4e8b\u7269\u5171\u540c\u672c\u8d28\u7684\u8fc7\u7a0b\u3002\u5c06\u590d\u6742\u7684\u73b0\u5b9e\uff0c\u7b80\u5316\u6210\u5355\u7eaf\u7684\u6a21\u578b\uff0c\u8fd9\u79cd\u62bd\u8c61\u5316\u65b9\u5f0f\u79f0\u4e3a\u6a21\u578b\u5316\uff0c\u6240\u8c13\u95ee\u9898\u5efa\u6a21\uff0c\u5c31\u662f\u5bf9\u95ee\u9898\u8fdb\u884c\u6a21\u578b\u5316\uff0c\u4e5f\u5373\u62bd\u8c61\u7684\u8fc7\u7a0b\u3002\u5177\u4f53\u7684\u6982\u5ff5\u76f8\u5bf9\u7b80\u5355\uff0c\u5c31\u662f\u6307\u770b\u5f97\u89c1\u6478\u5f97\u7740\u7684\u4e8b\u7269\uff0c\u6bcf\u4e2a\u4e8b\u7269\u90fd\u662f\u72ec\u4e00\u65e0\u4e8c\u7684\uff0c\u662f\u4ee5\u53d8\u5316\u5c24\u76db\u3002\u5177\u4f53\u5316\u5c31\u662f\u5c06\u62bd\u8c61\u4e8b\u7269\u52a0\u8f7d\u6e05\u6670\u7684\u8fc7\u7a0b\uff0c\u662f\u4e00\u79cd\u6709\u52a9\u4e8e\u7406\u89e3\u964c\u751f\u4e8b\u7269\u7684\u65b9\u5f0f\u3002\u6570\u636e\u7c7b\u578b\u662f\u5177\u4f53\u4e8b\u7269\uff0c\u80fd\u591f\u6e05\u6670\u7b80\u660e\u5730\u5448\u73b0\u51fa\u4e0d\u540c\u6570\u636e\u7c7b\u578b\u7684\u5171\u540c\u903b\u8f91\uff0c\u5c31\u662f\u7528\u6a21\u677f\u7c7b\u578b\u4ee3\u66ff\u5177\u4f53\u7c7b\u578b\u7684\u7cbe\u5999\u4e4b\u5904\u3002 \u6a21\u677f\u672c\u8eab\u662f\u4e00\u79cd\u62bd\u8c61\u5316\u7684\u5de5\u5177\uff0c\u4ee5\u5176\u7f16\u5199\u7684\u662f\u62bd\u8c61\u903b\u8f91\uff0c\u8868\u793a\u67d0\u7c7b\u7c7b\u578b\u7684\u5171\u6709\u672c\u8d28\uff0c\u662f\u4e0d\u53d8\u7684\u90e8\u5206\u3002\u5176\u672c\u8eab\u662f\u6ca1\u6709\u7528\u7684\uff0c\u5b9e\u9645\u9700\u8981\u7684\u8fd8\u662f\u5177\u4f53\u903b\u8f91\uff0c\u56e0\u6b64\u9700\u8981\u6709\u5177\u4f53\u5316\u7684\u8fc7\u7a0b\uff0c\u5c06\u62bd\u8c61\u903b\u8f91\u8f6c\u53d8\u4e3a\u5177\u4f53\u903b\u8f91\u3002\u5728 C++ \u6a21\u677f\u4e2d\uff0c\u8fd9\u79cd\u5c06\u62bd\u8c61\u903b\u8f91\u8f6c\u53d8\u6210\u5177\u4f53\u903b\u8f91\u7684\u8fc7\u7a0b\uff0c\u79f0\u4e3a\u5b9e\u4f8b\u5316\u3002\u5b9e\u4f8b\u5316\u5c06\u5728\u7f16\u8bd1\u671f\u5c06\u62bd\u8c61\u7c7b\u578b\u66ff\u6362\u6210\u5177\u4f53\u7c7b\u578b\uff0c\u6839\u636e\u6a21\u677f\u751f\u6210\u4e00\u4e2a\u4e2a\u5177\u4f53\u903b\u8f91\u3002\u8fd9\u79cd\u5b9e\u4f8b\u5316\u673a\u5236\uff0c\u4fbf\u662f\u6211\u4eec\u6240\u9700\u8981\u7684\u4ee3\u7801\u751f\u6210\u80fd\u529b\u3002 \u4e0e\u5b8f\u4e0d\u540c\uff0c\u6a21\u677f\u5177\u4f53\u5316\u540e\u751f\u6210\u7684\u4ee3\u7801\uff0c\u5e76\u65e0\u6cd5\u76f4\u63a5\u5728\u751f\u6210\u7684\u6e90\u7801\u4e2d\u770b\u5230\uff0c\u4f46\u662f\u53ef\u4ee5\u901a\u8fc7 CppInsight \u8fd9\u7c7b\u5de5\u5177\u5bdf\u770b\u3002 \u6bd4\u5982\uff1a template &lt;typename T&gt; inline constexpr T Integer = 42; int&hellip; <a 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\u65f6\u671f\uff0c\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\u5de5\u5177\u9661\u589e\uff0c\u5176\u4e2d\u4ee5\u6a21\u677f\u4e3a\u4e00\u5207\u7684\u6839\u57fa\uff0c\u53d1\u679d\u6563\u53f6\uff0c\u5c14\u4eca\u6b63\u5411\u9759\u6001\u53cd\u5c04\u524d\u8fdb\u3002 \u672c\u7ae0\u6d89\u53ca\u4e0d\u8ba1\u5176\u6570\u7684\u6a21\u677f\u6280\u672f\uff0c\u4e3b\u8981\u96c6\u4e2d\u4e8e\u6a21\u677f\u7684\u6838\u5fc3\u7406\u8bba\u548c\u7528\u6cd5\uff0c\u6982\u5ff5\u9519\u7efc\u590d\u6742\uff0c\u6280\u672f\u5c42\u51fa\u4e0d\u7a77\u3002\u96be\u5ea6\u7b49\u7ea7\u7edd\u5bf9\u4e0d\u4f4e\uff0c\u662f\u672c\u7cfb\u5217\u4e2d\u975e\u5e38\u91cd\u8981\u7684\u4e00\u7ae0\u3002 \u7eb5\u7136\u67d0\u4e9b\u6982\u5ff5\u548c\u6280\u672f\u4f60\u5df2\u77e5\u6089\uff0c\u4e5f\u83ab\u8981\u8df3\u8fc7\u67d0\u4e2a\u5c0f\u8282\uff0c\u56e0\u4e3a\u672c\u7cfb\u5217\u7684\u91cd\u5fc3\u4e0d\u5728\u6a21\u677f\u7f16\u7a0b\uff0c\u800c\u5728\u4ea7\u751f\u5f0f\u7f16\u7a0b\uff0c\u8bba\u8ff0\u89d2\u5ea6\u5c06\u6709\u6240\u5dee\u5f02\u3002 \u6cdb\u578b\u2026\u2026\u5143\u7f16\u7a0b \u4f20\u7edf\u8fc7\u7a0b\u5f0f\u7f16\u7a0b\u7684\u601d\u8def\u662f\u5c06\u903b\u8f91\u4f5c\u4e3a\u51fd\u6570\uff0c\u6570\u636e\u4f5c\u4e3a\u51fd\u6570\u7684\u8f93\u5165\u548c\u8f93\u51fa\uff0c\u901a\u8fc7\u65e0\u6570\u4e2a\u51fd\u6570\u6765\u7ec4\u7ec7\u5b8c\u6574\u7684\u903b\u8f91\u9700\u6c42\uff0c\u597d\u4f3c\u642d\u79ef\u6728\uff0c\u6784\u5efa\u51fa\u5404\u79cd\u7269\u4f53\u3002 \u9762\u5411\u5bf9\u8c61\u7f16\u7a0b\u66f4\u8fdb\u4e00\u6b65\uff0c\u601d\u8def\u662f\u5c06\u903b\u8f91\u548c\u6570\u636e\u5408\u5e76\u8d77\u6765\uff0c\u6784\u6210\u4e00\u4e2a\u4e2a\u7c7b\uff0c\u7c7b\u4e2d\u5305\u542b\u5404\u79cd\u6570\u636e\u548c\u51fd\u6570\uff0c\u5916\u90e8\u53ea\u80fd\u501f\u52a9\u516c\u5f00\u51fd\u6570\u64cd\u7eb5\u8fd9\u4e9b\u6570\u636e\u3002\u8fd9\u79cd\u4ee5\u5bf9\u8c61\u8868\u793a\u73b0\u5b9e\u4e8b\u7269\u7684\u65b9\u5f0f\u4e0e\u4eba\u7684\u601d\u7ef4\u66f4\u52a0\u63a5\u8fd1\uff0c\u7b80\u5316\u4e86\u62bd\u8c61\u5316\u7684\u96be\u5ea6\u3002 \u6cdb\u578b\u7f16\u7a0b\u5219\u6b32\u5c06\u903b\u8f91\u548c\u6570\u636e\u5206\u79bb\uff0c\u5e76\u63d0\u4f9b\u4e00\u79cd\u62bd\u8c61\u5316\u6570\u636e\u7684\u65b9\u5f0f\uff0c\u4f7f\u5f97\u4e0d\u540c\u7684\u6570\u636e\u80fd\u591f\u4f7f\u7528\u540c\u4e00\u79cd\u903b\u8f91\uff0c\u6781\u5927\u964d\u4f4e\u4e86\u4ee3\u7801\u7684\u91cd\u590d\u6027\u3002\u4e8e\u662f\uff0c\u540c\u4e00\u4e2a\u51fd\u6570\u80fd\u591f\u4f20\u9012\u4e0d\u540c\u7684\u53c2\u6570\u7c7b\u578b\uff0c\u8fd9\u53eb\u51fd\u6570\u6a21\u677f\uff1b\u540c\u4e00\u4e2a\u7c7b\u80fd\u591f\u4f20\u9012\u4e0d\u540c\u7684\u6570\u636e\uff0c\u8fd9\u53eb\u7c7b\u6a21\u677f\u3002 C++ \u662f\u4e00\u79cd\u591a\u8303\u5f0f\u8bed\u8a00\uff0c\u4ee5\u6a21\u677f\u652f\u6301\u6cdb\u578b\u7f16\u7a0b\uff0c\u5141\u8bb8\u7f16\u5199\u6cdb\u578b\u7684\u51fd\u6570\u548c\u6570\u636e\uff0c\u529f\u80fd\u4e0d\u4f9d\u8d56\u4e8e\u67d0\u79cd\u5177\u4f53\u7684\u6570\u636e\u7c7b\u578b\uff0c\u4f7f\u7528 SFINAE \u548c Concepts \u7ea6\u675f\u62bd\u8c61\u5316\u7684\u7c7b\u578b\u3002\u8fd9\u79cd\u80fd\u529b\u4f7f\u5176\u652f\u6301 Parametric Polymorphism\uff0c\u5728\u591a\u6001\u7684\u9009\u62e9\u4e0a\u4e0d\u5fc5\u5c40\u9650\u4e8e\u4f20\u7edf\u7684 Subtype Polymorphism\uff0c\u53ef\u4ee5\u4f7f\u7528\u7f16\u8bd1\u671f\u591a\u6001\u66ff\u4ee3\u8fd0\u884c\u671f\u591a\u6001\u3002 C++ \u4e2d\uff0c\u5143\u7f16\u7a0b\u6307\u7684\u662f\u53d1\u751f\u4e8e\u7f16\u8bd1\u671f\u7684\u7f16\u7a0b\uff0c\u6a21\u677f\u4e3a C++ \u5e26\u6765\u6cdb\u578b\u7f16\u7a0b\u7684\u540c\u65f6\uff0c\u4e5f\u5e26\u6765\u4e86\u5143\u7f16\u7a0b\u80fd\u529b\u3002\u7531\u6a21\u677f\u5b9e\u73b0\u7684\u5143\u7f16\u7a0b\uff0c\u79f0\u4e3a\u6a21\u677f\u5143\u7f16\u7a0b\u3002\u800c\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\uff0c\u6307\u7684\u662f\u53d1\u751f\u4e8e\u7f16\u8bd1\u671f\u7684\u5bf9\u4e8e\u7f16\u7a0b\u7684\u7f16\u7a0b\uff0c\u6a21\u677f\u672c\u5c31\u652f\u6301\u5728\u7f16\u8bd1\u671f\u751f\u6210\u4ee3\u7801\uff0c\u56e0\u6b64\u6a21\u677f\u4e5f\u80fd\u591f\u5b9e\u73b0\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\u3002 \u62bd\u8c61\u5316\u3001\u5177\u4f53\u5316\u2026\u2026\u6a21\u677f \u5728\u6a21\u677f\u4e16\u754c\u4e2d\uff0c\u51fd\u6570\u4e0d\u518d\u662f\u5177\u4f53\u7684\u51fd\u6570\uff0c\u6570\u636e\u7c7b\u578b\u4e5f\u4e0d\u518d\u662f\u5177\u4f53\u7684\u6570\u636e\u7c7b\u578b\u3002\u6a21\u677f\u5b9b\u5982\u4e00\u4e2a\u6a21\u5177\uff0c\u501f\u5176\u80fd\u591f\u4ea7\u751f\u5404\u5f0f\u5404\u6837\u7684\u7269\u4f53\uff0c\u8fd9\u4e9b\u7269\u4f53\u7684\u989c\u8272\u3001\u6750\u6599\u53ef\u80fd\u4e0d\u5c3d\u76f8\u540c\uff0c\u4f46\u662f\u5f62\u72b6\u3001\u5927\u5c0f\u662f\u4e00\u81f4\u7684\u3002\u4e5f\u5c31\u662f\u8bf4\uff0c\u4e00\u7c7b\u7269\u4f53\uff0c\u5fc5\u987b\u5b58\u5728\u5171\u540c\u7684\u90e8\u5206\uff0c\u624d\u80fd\u591f\u62bd\u8c61\u51fa\u4e00\u4e2a\u6a21\u5177\uff0c\u6a21\u5177\u7684\u4f5c\u7528\u5c31\u662f\u91cd\u590d\u5229\u7528\u8fd9\u4e9b\u5171\u540c\u4e4b\u5904\uff0c\u51cf\u5c11\u91cd\u590d\u6027\u3002 \u7f16\u7a0b\u662f\u5de5\u5177\uff0c\u672c\u8d28\u662f\u89e3\u51b3\u95ee\u9898\uff0c\u89e3\u51b3\u95ee\u9898\u8003\u9a8c\u7684\u5c31\u662f\u62bd\u8c61\u5316\u548c\u5177\u4f53\u5316\u7684\u80fd\u529b\u3002\u62bd\u8c61\u5316\u5e94\u5bf9\u7684\u662f\u73b0\u5b9e\u4e16\u754c\u4e2d\u7684\u4e0d\u53d8\uff0c\u800c\u5177\u4f53\u5316\u5e94\u5bf9\u7684\u662f\u73b0\u5b9e\u4e16\u754c\u4e2d\u7684\u53d8\u5316\uff0c\u80fd\u591f\u6e05\u695a\u5730\u8ba4\u8bc6\u5230\u53d8\u4e0e\u4e0d\u53d8\u662f\u4ec0\u4e48\uff0c\u95ee\u9898\u4e5f\u5c31\u8fce\u5203\u800c\u89e3\u4e86\u3002\u90a3\u5148\u6765\u5206\u6e05\u62bd\u8c61\u5316\u548c\u5177\u4f53\u5316\u7684\u6982\u5ff5\u3002 \u62bd\u8c61\u7684\u610f\u601d\u662f\uff0c\u5728\u8bb8\u591a\u4e8b\u7269\u4e2d\uff0c\u53bb\u9664\u975e\u672c\u8d28\u7684\u5c5e\u6027\uff0c\u62bd\u51fa\u672c\u8d28\u5c5e\u6027\u3002\u62bd\u8c61\u5316\u5c31\u662f\u5448\u73b0\u51fa\u5177\u4f53\u4e8b\u7269\u5171\u540c\u672c\u8d28\u7684\u8fc7\u7a0b\u3002\u5c06\u590d\u6742\u7684\u73b0\u5b9e\uff0c\u7b80\u5316\u6210\u5355\u7eaf\u7684\u6a21\u578b\uff0c\u8fd9\u79cd\u62bd\u8c61\u5316\u65b9\u5f0f\u79f0\u4e3a\u6a21\u578b\u5316\uff0c\u6240\u8c13\u95ee\u9898\u5efa\u6a21\uff0c\u5c31\u662f\u5bf9\u95ee\u9898\u8fdb\u884c\u6a21\u578b\u5316\uff0c\u4e5f\u5373\u62bd\u8c61\u7684\u8fc7\u7a0b\u3002\u5177\u4f53\u7684\u6982\u5ff5\u76f8\u5bf9\u7b80\u5355\uff0c\u5c31\u662f\u6307\u770b\u5f97\u89c1\u6478\u5f97\u7740\u7684\u4e8b\u7269\uff0c\u6bcf\u4e2a\u4e8b\u7269\u90fd\u662f\u72ec\u4e00\u65e0\u4e8c\u7684\uff0c\u662f\u4ee5\u53d8\u5316\u5c24\u76db\u3002\u5177\u4f53\u5316\u5c31\u662f\u5c06\u62bd\u8c61\u4e8b\u7269\u52a0\u8f7d\u6e05\u6670\u7684\u8fc7\u7a0b\uff0c\u662f\u4e00\u79cd\u6709\u52a9\u4e8e\u7406\u89e3\u964c\u751f\u4e8b\u7269\u7684\u65b9\u5f0f\u3002\u6570\u636e\u7c7b\u578b\u662f\u5177\u4f53\u4e8b\u7269\uff0c\u80fd\u591f\u6e05\u6670\u7b80\u660e\u5730\u5448\u73b0\u51fa\u4e0d\u540c\u6570\u636e\u7c7b\u578b\u7684\u5171\u540c\u903b\u8f91\uff0c\u5c31\u662f\u7528\u6a21\u677f\u7c7b\u578b\u4ee3\u66ff\u5177\u4f53\u7c7b\u578b\u7684\u7cbe\u5999\u4e4b\u5904\u3002 \u6a21\u677f\u672c\u8eab\u662f\u4e00\u79cd\u62bd\u8c61\u5316\u7684\u5de5\u5177\uff0c\u4ee5\u5176\u7f16\u5199\u7684\u662f\u62bd\u8c61\u903b\u8f91\uff0c\u8868\u793a\u67d0\u7c7b\u7c7b\u578b\u7684\u5171\u6709\u672c\u8d28\uff0c\u662f\u4e0d\u53d8\u7684\u90e8\u5206\u3002\u5176\u672c\u8eab\u662f\u6ca1\u6709\u7528\u7684\uff0c\u5b9e\u9645\u9700\u8981\u7684\u8fd8\u662f\u5177\u4f53\u903b\u8f91\uff0c\u56e0\u6b64\u9700\u8981\u6709\u5177\u4f53\u5316\u7684\u8fc7\u7a0b\uff0c\u5c06\u62bd\u8c61\u903b\u8f91\u8f6c\u53d8\u4e3a\u5177\u4f53\u903b\u8f91\u3002\u5728 C++ \u6a21\u677f\u4e2d\uff0c\u8fd9\u79cd\u5c06\u62bd\u8c61\u903b\u8f91\u8f6c\u53d8\u6210\u5177\u4f53\u903b\u8f91\u7684\u8fc7\u7a0b\uff0c\u79f0\u4e3a\u5b9e\u4f8b\u5316\u3002\u5b9e\u4f8b\u5316\u5c06\u5728\u7f16\u8bd1\u671f\u5c06\u62bd\u8c61\u7c7b\u578b\u66ff\u6362\u6210\u5177\u4f53\u7c7b\u578b\uff0c\u6839\u636e\u6a21\u677f\u751f\u6210\u4e00\u4e2a\u4e2a\u5177\u4f53\u903b\u8f91\u3002\u8fd9\u79cd\u5b9e\u4f8b\u5316\u673a\u5236\uff0c\u4fbf\u662f\u6211\u4eec\u6240\u9700\u8981\u7684\u4ee3\u7801\u751f\u6210\u80fd\u529b\u3002 \u4e0e\u5b8f\u4e0d\u540c\uff0c\u6a21\u677f\u5177\u4f53\u5316\u540e\u751f\u6210\u7684\u4ee3\u7801\uff0c\u5e76\u65e0\u6cd5\u76f4\u63a5\u5728\u751f\u6210\u7684\u6e90\u7801\u4e2d\u770b\u5230\uff0c\u4f46\u662f\u53ef\u4ee5\u901a\u8fc7 CppInsight \u8fd9\u7c7b\u5de5\u5177\u5bdf\u770b\u3002 \u6bd4\u5982\uff1a template &lt;typename T&gt; inline constexpr T Integer = 42; int&hellip; Continue Reading \u300a\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\u300b\u7b2c\u4e94\u7ae0 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\u6a21\u677f\u672c\u8eab\u662f\u4e00\u79cd\u62bd\u8c61\u5316\u7684\u5de5\u5177\uff0c\u4ee5\u5176\u7f16\u5199\u7684\u662f\u62bd\u8c61\u903b\u8f91\uff0c\u8868\u793a\u67d0\u7c7b\u7c7b\u578b\u7684\u5171\u6709\u672c\u8d28\uff0c\u662f\u4e0d\u53d8\u7684\u90e8\u5206\u3002\u5176\u672c\u8eab\u662f\u6ca1\u6709\u7528\u7684\uff0c\u5b9e\u9645\u9700\u8981\u7684\u8fd8\u662f\u5177\u4f53\u903b\u8f91\uff0c\u56e0\u6b64\u9700\u8981\u6709\u5177\u4f53\u5316\u7684\u8fc7\u7a0b\uff0c\u5c06\u62bd\u8c61\u903b\u8f91\u8f6c\u53d8\u4e3a\u5177\u4f53\u903b\u8f91\u3002\u5728 C++ \u6a21\u677f\u4e2d\uff0c\u8fd9\u79cd\u5c06\u62bd\u8c61\u903b\u8f91\u8f6c\u53d8\u6210\u5177\u4f53\u903b\u8f91\u7684\u8fc7\u7a0b\uff0c\u79f0\u4e3a\u5b9e\u4f8b\u5316\u3002\u5b9e\u4f8b\u5316\u5c06\u5728\u7f16\u8bd1\u671f\u5c06\u62bd\u8c61\u7c7b\u578b\u66ff\u6362\u6210\u5177\u4f53\u7c7b\u578b\uff0c\u6839\u636e\u6a21\u677f\u751f\u6210\u4e00\u4e2a\u4e2a\u5177\u4f53\u903b\u8f91\u3002\u8fd9\u79cd\u5b9e\u4f8b\u5316\u673a\u5236\uff0c\u4fbf\u662f\u6211\u4eec\u6240\u9700\u8981\u7684\u4ee3\u7801\u751f\u6210\u80fd\u529b\u3002 \u4e0e\u5b8f\u4e0d\u540c\uff0c\u6a21\u677f\u5177\u4f53\u5316\u540e\u751f\u6210\u7684\u4ee3\u7801\uff0c\u5e76\u65e0\u6cd5\u76f4\u63a5\u5728\u751f\u6210\u7684\u6e90\u7801\u4e2d\u770b\u5230\uff0c\u4f46\u662f\u53ef\u4ee5\u901a\u8fc7 CppInsight \u8fd9\u7c7b\u5de5\u5177\u5bdf\u770b\u3002 \u6bd4\u5982\uff1a template &lt;typename T&gt; inline constexpr T Integer = 42; int&hellip; Continue Reading \u300a\u4ea7\u751f\u5f0f\u5143\u7f16\u7a0b\u300b\u7b2c\u4e94\u7ae0 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