From: Trans <transfire@...>
Date: 2005-11-05T14:37:10+09:00
Subject: Re: lazy.rb


Pit Capitain wrote:
> MenTaLguY schrieb:
> > ...
> > Same problem in both cases, basically.
>
> Here's another implementation that doesn't have these problems:
>
>    module Lazy #:nodoc: all
>      class Thunk
>        instance_methods.each { |m| undef_method m unless m =~ /^__/ }
>        def initialize( &computation )
>          @computation = computation
>        end
>        def method_missing( *args, &block )
>          ( @result ||= @computation.call( self ) ).send( *args, &block )
>        end
>      end
>    end

Ah, that clarifies things. This is essentially a pass-thru Functor with
a cached result. (Why is 'self' being passed to the computation
though?)  While not quite the same as the implict lambda's I suggested,
it is interesting just how similar they are.

This whole Functor paradigm, including things like #every, #enum_for,
#as (was #superfunc), etc. and now this --all are various simple
decorators of a special form where the heart of code is some sort of
transfomation in method_missing. Insteresting stuff. It would be even
more interesting to see if this could somehow be embodied in core so to
operate more efficiently (and perhaps a syntax variation on the
methods?)  --this techinque may have potential for roles and namespace
selectors too.

T.