From: Eric Mahurin <eric_mahurin@...>
Date: 2005-06-07T01:00:23+09:00
Subject: making a duck

Regarding duck-typing... Is there an easy way make a "duck"? 
i.e. an object that responds to enough methods to be an
acceptable argument to a certain methods.  For example, if I
have a method that takes aString and uses the #size and #[i]
methods, I could pass it something that looked just enough like
a String to work:

alphabet = Object.duck(:[],proc{|i|?a+i},:size,proc{26})

The implementation I came up with is this:

class Object
    def self.duck(*name_proc)
        duck = self.new
        duckclass = (class << duck;self;end)
        while not name_proc.empty?
            name,proc = name_proc.slice!(0,2)
            duckclass.send(:define_method,name,&proc)
        end
        duck
    end
end


Is there another way to do this?  With all of the talk about
duck-typing, there would already be something out there to do
this.



		
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