From: Daniel Schierbeck <daniel.schierbeck@...>
Date: 2005-11-26T22:32:28+09:00
Subject: Re: `finalize' method?

ts wrote:
>>>>>> "D" == Daniel Schierbeck <daniel.schierbeck@gmail.com> writes:
> 
> D> What would you call such an approach? Encapsulating? I use this often 
> D> enough that I think it would fit lovely in a module:
> 
>  A bad approach, at least for me.
> 
> D>          def self.new(*args)
> D>            yield obj = __new__(*args)
> D>            obj.finalize if obj.respond_to? :finalize
> D>          end
> 
>  There is a convention in ruby : the method ::new must return an object of
>  the class. You must change the name of the method if its return nil, or
>  another object.

Roger. That's not that hard to do:

   module Encapsulatable
     def self.included(klass)
       super
       klass.metaclass_eval do
         private :new

         def encapsulate(*args)
           yield obj = new(*args)
           obj.finalize if obj.respond_to? :finalize
         end
       end
     end
   end

Note that this doesn't prevent the user from calling methods on the 
object after its `finalize' method has been called.

   class Klass
     include Encapsulatable

     def initialize
       puts "initializing..."
     end

     def foo
       puts "called method `foo'"
     end

     def finalize
       puts "finalizing..."
     end
   end

   ref = nil
   Klass.encapsulate { |obj| obj.foo; ref = obj }
   ref.foo

But then again, this ain't Java. If you want to, you could wreak havoc 
in seconds. But we're all friends, right? :)


Cheers,
Daniel