From: Heesob Park <phasis@...>
Date: 2008-05-23T18:16:13+09:00
Subject: Re: Help extending Hash to allow hexadecimal encoded keys (problem with "Delegator")

Hi,

2008/5/23 Iñaki Baz Castillo <ibc@aliax.net>:
> 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.
>
>
Here is a modified version including find and find_all:

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

               def find(ifnone = nil,&blk)
                 __getobj__.find(ifnone,&blk)
               end

               def find_all(&blk)
                 __getobj__.find_all(&blk)
               end
       end  # class UriParametersHash


Regards,

Park Heesob