From: Robert Klemme <shortcutter@...>
Date: 2011-04-17T06:51:34+09:00
Subject: Re: looking for an "inversion" pattern

On 16.04.2011 23:14, Brian Candler wrote:
> Fearless Fool wrote in post #992929:
>> I'm sure there's a clean way to do this in Ruby, but I haven't figured
>> it out.
>>
>> I'd like to create a method +foo+ that transforms:
>>
>>     my_obj.foo.some_method(*args)
>>
>> to
>>
>>    MyClass.some_method(my_obj, *args)
>
> Not sure, but would bound or unbound methods help you?
>
> bound_method = my_obj.method(:foo)
> bound_method.call(*args)
>
> unbound_method = my_obj.class.instance_method(:foo)
> unbound_method.bind(my_obj).call(*args)

You can only bind to instances of the original type.  You cannot use 
#unbind and #bind to let a method be called on a different type.  But 
this would be necessary for the OP's requirement to be fulfilled.

irb(main):001:0> class Foo
irb(main):002:1> def self.bar;123;end
irb(main):003:1> end
=> nil
irb(main):004:0> m=Foo.method(:bar).unbind
=> #<UnboundMethod: #<Class:Foo>#bar>
irb(main):005:0> f=Foo.new
=> #<Foo:0x105a24a4>
irb(main):006:0> m.bind(f)
TypeError: singleton method called for a different object
         from (irb):6:in `bind'
         from (irb):6
         from /usr/local/bin/irb19:12:in `<main>'
irb(main):007:0> m.bind(Foo)
=> #<Method: Foo.bar>
irb(main):008:0> m.bind(Foo).call
=> 123

Kind regards

	robert

-- 
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