From: Shannon Fang <xrfang@...>
Date: 2005-10-25T14:05:07+09:00
Subject: Re: RCR: Array#to_h

I am just reading the PickAxe 2e recently... According to Dave, to_h means a 
representation of the object in hash, however to_hash means this object is 
inherently compatible with hash, like to_i and to_int...

We do need a good name for it :D

Shannon


>From: "Trans" <transfire@gmail.com>
>Reply-To: ruby-talk@ruby-lang.org
>To: ruby-talk@ruby-lang.org (ruby-talk ML)
>Subject: Re: RCR: Array#to_h
>Date: Tue, 25 Oct 2005 13:57:02 +0900
>
>Actually this has been bugging me as I currently have these:
>
>module Enumerable
>
>   # Produces a hash from an Enumerable with index for keys.
>   #
>   #   a1 = [ :a, :b ]
>   #   a1.to_h  #=> { 0=>:a, 1=>:b }
>   #
>   def to_h( &blk )
>     h = {}
>     if block_given?
>       each_with_index{ |e,i| h[i] = blk.call(e,i) }
>     else
>       each_with_index{ |e,i| h[i] = e }
>     end
>     h
>   end
>
>end
>
>class Array
>
>   # Produces a hash for an Array, or two arrays.
>   # It is just like Enumerbale#to_h but with an
>   # extra feature: If an array is given as the
>   # values, it is zipped with the receiver,
>   # to produce the hash.
>   #
>   #   a1 = [ :a, :b ]
>   #   a2 = [ 1, 2 ]
>   #   a1.to_h(a2)  #=> { :a=>1, :b=>2 }
>   #
>   def to_h(values=nil)
>     h = {}
>     if values
>       size.times{ |i| h[at(i)] = values.at(i) }
>     else
>       each_with_index{ |e,i| h[i] = e }
>     end
>     h
>   end
>
>   # Converts an associative array into a hash.
>   #
>   #   a = [ [:a,1], [:b,2] ]
>   #   a.assoc_to_h  #=> { :a=>1, :b=>2 }
>   #
>   #   a = [ [:a,1,2], [:b,3,4] ]
>   #   a.assoc_to_h(true)  #=> { :a=>[1,2], :b=>[3,4] }
>   #
>   def assoc_to_h(arrayed=nil)
>     h = {}
>     if arrayed
>       each{ |e| h[e.first] = e.slice(1..-1) }
>     else
>       each{ |e| h[e.first] = e.last }
>     end
>     h
>   end
>
>end
>
>I wish there was a good way just to have a single Array#to_h, but it
>doesn;t seem reasonable. Perhaps Enumerable#to_h could be #to_hash?
>
>T.
>
>