Ruby 1.9正则表达式作为散列键 [英] Ruby 1.9 regex as a hash key

问题描述

我正在尝试这个例子 myhash = {/（\ d +）/ => hello} with ruby​​ 1.9.2p136（2010-12-25）[i386-mingw32] 。

它没有像预期的那样工作（编辑：因为事实证明它不应该像我期待的那样工作）：

  irb （主）：004：0> myhash = {/（\ d +）/ => hello} 
 => {/（\ d +）/ =>Hello} 
 irb（main）：005：0> myhash [2222] 
 =>无
 irb（main）：006：0> myhash [2222] 
 => nil 
  

在 Rubular ，这是ruby1.8.7 正则表达式的作品。

我是什么失踪？

解决方案

如果没有额外的代码，它将无法正常工作，因为它是将Regexp对象与Integer或String目的。他们不会是价值平等，也不是身份平等。它们会匹配，但需要对Hash类代码进行更改。

  irb（main）：001：0> /(\d+)/.class 
 =>正则表达式
 irb（main）：002：0> 2222.class 
 => Fixnum 
 irb（main）：003：0> '2222'.class 
 =>字符串
 irb（main）：004：0> /（\ d +）/ == 2222 
 => false 
 irb（main）：007：0> /（\d +）/ =='2222'
 => false 
 irb（main）：009：0> /(\d+)/.equal?'2222'
 => false 
 irb（main）：010：0> /(\d+)/.equal?2222 
 => false 
  

您必须迭代哈希并使用=〜如下所示：

  hash.each do | k，v | 
除非（k =〜whatever.to_s）.nil？ 
 puts v 
 end 
 end 
  

或更改Hash类尝试=〜除了正常的匹配条件。 （我认为最后一个选项会很困难，在Hash类中，似乎有很多C代码）。

I am trying this example myhash = {/(\d+)/ => "hello"} with ruby 1.9.2p136 (2010-12-25) [i386-mingw32].
It doesn't work as expected (edit: as it turned out it shouldn't work as I was expecting):

irb(main):004:0> myhash = {/(\d+)/ => "hello"}
=> {/(\d+)/=>"Hello"}
irb(main):005:0> myhash[2222]
=> nil
irb(main):006:0> myhash["2222"]
=> nil

In Rubular which is on ruby1.8.7 the regex works.
What am I missing?

解决方案

It will not work without some extra code, as it is you are comparing a Regexp object with either an Integer or a String object. They won't be value equal, nor identity equal. They would match but that requires changes to the Hash class code.

irb(main):001:0> /(\d+)/.class
=> Regexp
irb(main):002:0> 2222.class
=> Fixnum
irb(main):003:0> '2222'.class
=> String
irb(main):004:0> /(\d+)/==2222
=> false
irb(main):007:0> /(\d+)/=='2222'
=> false
irb(main):009:0> /(\d+)/.equal?'2222'
=> false
irb(main):010:0> /(\d+)/.equal?2222
=> false

you would have to iterate the hash and use =~ in something like:

 hash.each do |k,v|    
   unless (k=~whatever.to_s).nil?
     puts v   
   end
 end

or change the Hash class to try =~ in addition to the normal matching conditions. (I think that last option would be difficult, in mri the Hash class seems to have a lot of C code)

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