From: Ittay Dror <ittay.dror@...>
Date: 2008-11-22T04:40:28+09:00
Subject: Re: how to wrap method of singleton class

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James Coglan wrote:
>> How do I write a module, so that when included in Foo it will wrap the
>> method foo so that Foo.foo will print:
>>     
>
>
>
> You can't (at least not without doing some sneaky metaprogramming -- this
> code is still a work in progress: http://gist.github.com/25104). A class's
> own methods take precedence over any modules mixed into it. What you can do
> is reopen the singleton class and store a reference to the old method:
>
> class << Foo # Foo singleton class
>   old_foo = Foo.method(:foo)
>   define_method(:foo) do |*args|
>     old_result = old_foo.call(*args)
>     old_result.upcase
>   end
> end
>
>   
doing it this way, i can do:
class << Foo
  alias_method :original, :foo
  def foo
     puts 'bar'
     original
  end
end

but i want a module i can mix in. (for regular methods, the module can 
use the included callback to alias the methods, just not sure how to do 
that for a singleton class)
> Foo.foo #=> "FOO"
>
> You must use define_method for this instead of def. def does not use a block
> so you won't get a closure, which you need to retain visibility of the
> old_foo variable.
>
>   

-- 
Ittay Dror <ittayd@tikalk.com>
Tikal <http://www.tikalk.com>
Tikal Project <http://tikal.sourceforge.net>


-- 
--
Ittay Dror <ittay.dror@gmail.com>


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