From: Adam Prescott <adam@...>
Date: 2011-05-26T04:09:47+09:00
Subject: [ruby-core:36473] Re: [Ruby 1.9 - Feature #4772] Hash#add_keys

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On Wed, May 25, 2011 at 3:20 PM, Joey Zhou <yimutang@gmail.com> wrote:

> 1) hash = Hash.new {|h,k| k.succ }
> 2) hash = Hash.new {|h,k| h[k] = k.succ }
>
> 1) and 2) are different, 2) will actually create any key/value pair the
> hash ever seen a key, but 1) will not, it needs an assignment.
>

Ah I see, I missed the lack of assignment in the block to Hash.new. I
suppose potentially there's some confusion that might come up when using
Hash#add_keys and Hash.new given that one block is being used for both
purposes?

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<div class=3D"gmail_quote">On Wed, May 25, 2011 at 3:20 PM, Joey Zhou <span=
 dir=3D"ltr">&lt;<a href=3D"mailto:yimutang@gmail.com">yimutang@gmail.com</=
a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0=
 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">

<div id=3D":16q">1) hash =3D Hash.new {|h,k| k.succ }<br>
2) hash =3D Hash.new {|h,k| h[k] =3D k.succ }<br>
<br>
1) and 2) are different, 2) will actually create any key/value pair the has=
h ever seen a key, but 1) will not, it needs an assignment.<br></div></bloc=
kquote></div><br><div>Ah I see, I missed the lack of assignment in the bloc=
k to Hash.new. I suppose potentially there&#39;s some confusion that might =
come up when using Hash#add_keys and Hash.new given that one block is being=
 used for both purposes?</div>


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