From: Robert Klemme <shortcutter@...>
Date: 2008-04-23T18:45:55+09:00
Subject: Re: Extending Hast class with custom [] []= methods

2008/4/23, Iņaki Baz Castillo <ibc@aliax.net>:
> 2008/4/23, Chris Shea <cmshea@gmail.com>:
>
>
> > But he asking for case-insensitivity.  If a key is created with
>  >  uppercase letters, you're out of luck.  And if you look for a value
>  >  for a non-string key, that's no good either:
>
>
> Yeah, finally I've done:
>
>                 class InsensitiveHash < Hash
>                         def [](key)
>                                 find {|h| h[0] =~ /^#{key}$/i }[1]
>                         end
>                 end
>
>
>  It works. :)

... and is awfully inefficient.

Here's another way, which is more efficient for large hashes

class CiHash2 < DelegateClass(Hash)
  CiString = Struct.new :string do
    def to_s; string.downcase end
    def hash; string.downcase.hash end
    def eql?(s) string.downcase.eql? s.string.downcase end
    alias == eql?
    def inspect; string.inspect; end
  end

  def initialize
    super({})
  end

  def []=(k,v)
    k = CiString.new(k) if String === k
    __getobj__[k] = v
  end

  def [](k)
    k = CiString.new(k) if String === k
    __getobj__[k]
  end

  # add other lookup and mutation methods
end

h = CiHash2.new
h["FOO"]=3
h["Foo"]=4
puts h["foo"]
puts h["fOo"]
p h

Cheers

robert

-- 
use.inject do |as, often| as.you_can - without end