From: Brian Candler <b.candler@...>
Date: 2009-10-20T21:02:32+09:00
Subject: Re: instance_eval with method proc

Brian Candler wrote:
> If the method is in a common superclass, then you can make an 
> UnboundMethod and bind it to the new object. e.g.
> 
>>> class Foo; def foo; puts inspect; end; end
> => nil
>>> class Bar < Foo; end
> => nil
>>> b = Bar.new
> => #<Bar:0xb7c04998>
>>> Foo.instance_method(:foo).bind(b).call
> #<Bar:0xb7c04998>
> => nil
>>> 

... and of course, object b usually has the 'foo' method already 
inherited from the parent, in which case b.send(:foo) is sufficient.

But if 'foo' has been overridden, it can still be useful to bind this 
way.

>> class Foo; def foo; puts "foo from parent"; end; end
=> nil
>> class Bar < Foo; def foo; puts "foo from child"; end; end
=> nil
>> b = Bar.new
=> #<Bar:0xb7cf1cfc>
>> b.send(:foo)
foo from child
=> nil
>> m = Foo.instance_method(:foo)
=> #<UnboundMethod: Foo#foo>
>> m.bind(b).call
foo from parent
=> nil
-- 
Posted via http://www.ruby-forum.com/.