From: Ara.T.Howard@...
Date: 2005-04-30T05:04:38+09:00
Subject: Re: Creating arbitrary objects

On Sat, 30 Apr 2005, Matthew Thill wrote:

> I've probably overlooked something, and hopefully someone can help me
> out. I want to be able to create arbitrary object from the contents of a
> string.
>
> For example, if I had the following string:
>
> classname = "Array"
>
> How can I create an Array object, knowing only that the variable
> classname held the name of some class as a string.

this is from my utility lib:

   harp:~ > cat a.rb
   def klass_stamp(hierachy, *a, &b)
     ancestors = hierachy.split(%r/::/)
     parent = Object
     while((child = ancestors.shift))
       klass = parent.const_get child
       parent = klass
     end
     klass::new(*a, &b)
   end

   module A
     module B
       module C
         class X
           class Y
             class Z
               def initialize(*bits, &block)
                 n = 0
                 bits.reverse.each_with_index{|bit, i| n |= (bit << i)}
                 block.call n
               end
             end
           end
         end
       end
     end
   end

   klass_stamp('A::B::C::X::Y::Z', 1, 0, 1, 0, 1, 0){ |n| p n }

   harp:~ > ruby a.rb
   42


HTH.

-a
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