From: Logan Capaldo <logancapaldo@...>
Date: 2006-07-12T13:49:32+09:00
Subject: Re: alias new???


On Jul 12, 2006, at 12:07 AM, David Chelimsky wrote:

> I've seen this work before:
>
> module MagicWithMethodMissing
>   alias_method :__orig_method_missing, :method_missing
>   def method_missing(sym, *args, &block)
>     if some_condition
>       #do special stuff
>     else
>       __orig_method_missing(sym, *args, &block)
>     end
>   end
> end
>
> class MyClass
>   include MagicWithMethodMissing
> end
>
> I want to do the same thing w/ :new on the class
>
> module MagicWithNew
>   alias_method :__orig_new, :new
>   def new(*args, &block)
>     if some_condition
>       #do special stuff
>     else
>       __orig_new(*args, &block)
>     end
>   end
> end
>
> The question I have is how do I get this included in the meta class  
> of MyClass?
>
> Thanks,
> David
>
>
>

Couple of things
1) alias_method gets executed at "compile" time. This means that it  
will try to alias MagicWithNew.

2) This is ok because you dont want to use alias's in this case.  
Since #new is almost never overriden (it's usually #initialize.  
Incidentally are you sure you don't want to define #initialize  
instead?) it's pretty much guaranteed that you class is using the  
original implementation in Class.
so we can use inheritance and super


module MagicWithNew
   def new(*args, &block)
     if some_condition
        do_special_stuff
     else
        super
     end
   end
end

class MyClass
   extend MagicWithNew # note #extend,  not #include
end