From: Joey Zhou <yimutang@...>
Date: 2011-05-25T22:35:33+09:00
Subject: [ruby-core:36458] [Ruby 1.9 - Feature #4772] Hash#add_keys


Issue #4772 has been updated by Joey Zhou.


Yukihiro Matsumoto wrote:
> I see no reason to add a method to generate keys only.  Hash is a set of key-value pairs, right?  Can you elaborate why you want this method?
> 
> matz.

Maybe the method name leads to misunderstanding. What I mean is that I give keys, the hash generate values automatically, not generating keys only.

For example:

hash = Hash.new {|h,k| k + k.succ}
hash.add_keys("a","b","c")

Now, the hash should be {"a"=>"ab","b"=>"bc","c"=>"cd"}

In recent version, if I want to do the same thing, the code may be:

hash = Hash.new {|h,k| k + k.succ}
["a","b","c"].each do |key|
  hash[key] = hash[key] # this kind of assignment is somewhat odd
end

hash = Hash.new {|h,k| h[k] = k + k.succ}
["a","b","c"].each do |key|
  hash[key] # making key appears means making it exists? odd too.
end

So I think a method "filling hash with given keys and auto-generated values" is OK.

The name and parameter detail may be thought over.

Joey
----------------------------------------
Feature #4772: Hash#add_keys
http://redmine.ruby-lang.org/issues/4772

Author: Joey Zhou
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 


Hi, do you want to add a new method Hash#add_keys in a new version?

hash = Hash.new {|h,k| k.to_s + "foo" }
hash.add_keys("a","b","c") # the value is hash's default obj or proc value

If there's a word list file, I want to make the words keys of a hash, maybe I can write:

hash = {}
hash.add_keys(*open("file").readlines.map(&:chomp))




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