From: Ken Bloom <kbloom@...>
Date: 2006-09-09T05:00:14+09:00
Subject: Re: better alias_method

On Sat, 09 Sep 2006 02:54:35 +0900, Trans wrote:

> ara.t.howard@noaa.gov wrote:
>> heh.  i think you may be hitting the same thing i was.  here's some food for
>> thought:
>>
>>
>> this works:
>>
>>      harp:~ > cat a.rb
>>      class C
>>        include Module.new{ def m() 'a' end }
>>        include Module.new{ def m() super + 'b' end }
>>        include Module.new{ def m() super + 'c' end }
>>      end
>>
>>      p C.new.m
>>
>>
>>      harp:~ > ruby a.rb
>>      "abc"
>>
>>
>> while this does not:
>>
>>      harp:~ > cat a.rb
>>      class C
>>        def m() '' end
>>
>>        include Module.new{ def m() super + 'a' end }
>>        include Module.new{ def m() super + 'b' end }
>>        include Module.new{ def m() super + 'c' end }
>>      end
>>
>>      p C.new.m
>>
>>
>>      harp:~ > ruby a.rb
>>      ""
>>
>> even more distilled:
>>
>>      harp:~ > cat a.rb
>>      class C
>>        def m() '' end
>>
>>        include Module.new{ def m() 'a' end }
>>      end
>>
>>      p C.new.m
>>
>>
>>      harp:~ > ruby a.rb
>>      ""
>>
>>
>> i find that behviour quite suprising... in fact, it seems like a bug, but i'm
>> probably wrong...  thoughts?
> 
> Not at all becasue inclusion adds to the inheritance chain, it doesn't
> inject methods. You can of course define an #inject method if you like.
> But it's still difficult to do the orginial intent of this thread b/c
> of how #super works.
> 
> Personally I think it would cool if you could redefine a method calling
> on the previous definition just as one can redefine a variable calling
> on it's previous definition. Eg.
> 
>   a = 1
>   a = a + 1
> 
>   def a ; 1 ; end
>   def a ; a + 1 ; end
> 
> This would eliminate the need for #super except in cases of recursion,
> in which case a special notation is also needed for the definition. Eg.
> def_rec a, or something. But that's cool b/c it would be safer.
> 
> In anycase, alternate solutions to the alias issue include
> #wrap_method,

see http://www.erikveen.dds.nl/monitorfunctions/index.html#implementation

> #alias_chain, Matz' :before and :after system (semi-aop) and cuts (aop).

Where is there information about these?

--Ken

-- 
Ken Bloom. PhD candidate. Linguistic Cognition Laboratory.
Department of Computer Science. Illinois Institute of Technology.
http://www.iit.edu/~kbloom1/