From: "Iñaki Baz Castillo" <ibc@...>
Date: 2008-05-23T17:18:52+09:00
Subject: Help extending Hash to allow hexadecimal encoded keys (problem with "Delegator")

Hi, basically I need to implement a Hash in which keys can be encoded
with "pseudo" hexadecimal. This is basically to store URI parameters
and headers (defined in RFC 2396), so:

   "tag"  ==  "t%61g"
  "alice" == "%61l%69ce"

I'm implementing a UriParametersHash using "Derivate" (thanks to Robert Klemme):

-----------------------
	require 'delegate'
	class UriParametersHash < DelegateClass(Hash)
	
		CiString = Struct.new :string do
			
			def unescape(string)
				eval %{ "#{ string.gsub(/%/,'\x') }" }
			end
			private :unescape
			
			def to_s
				string.downcase
			end
			
			def hash
				unescape(string.downcase).hash
			end
			
			def eql?(s)
				unescape(string.downcase).eql? unescape(s.string.downcase)
			end
			alias == eql?
			
			def inspect; string.inspect; end
			
		end  # CiString
			
		def initialize
			super({})
		end
		
		attr_accessor :modified
		
		def []=(k,v)
			k = CiString.new(k) if String === k
			__getobj__[k] = v
		end
		
		def [](k)
			k = CiString.new(k) if String === k
		end

	end  # class UriParametersHash
-----------------------


It works ok:

@uri
=> {"a"=>123, "T%61g"=>"lalala"}

@uri["tag"]
=> "lalala"

@uri["T%61G"] = "lololo"
=> "lololo"


But I need to implement other Hash methods as "delete", "find",
"find_all"... and I get into problems: For example I define "find" in
this way:

		def find()
			k = CiString.new(k) if String === k
			__getobj__"find" (k)
		end


But it gives me an error:

	@uri.find{|e| e[0]=="tag"}
	ArgumentError: wrong number of arguments (1 for 0)
        	from uri.rb:100:in `__getobj__'
	        from uri.rb:100:in `find'


Unfortunatelly I don't find good documentation to handle
__getobj__method, could somebody give me a tip please? Thanks a lot.


-
Iñaki Baz Castillo
<ibc@aliax.net>