From: Trans <transfire@...>
Date: 2006-03-19T15:33:48+09:00
Subject: Functor Opinion

So here's the Functor class:

  class Functor < BasicObject
    def initialize(*obj, &func)
      @obj = obj
      @func = func
    end
    def method_missing(op, *args)
      if @obj.empty?
        @func.call(op, *args)
      else
        @func.call(op, *(@obj + args))
      end
    end
  end

Anyone who has seen the older version of this cllas will notice that I
have added the *obj parameter. This allows the Functor to act like a
simple delegator too. But strictly speaking it isn't at all necessary
since one could just use the object(s) passed to the initialize
directly in the block. Eg.

  foo = 1
  Functor.new(foo) { |op, obj, *args| obj.send(op, *args) }

is the exact same as

  foo = 1
  Functor.new { |op, *args| foo.send(op, *args) }

The only time this really is a little more handy is when passing
'self', because of the ambiguity between contexts. Eg.

  Functor.new(self) { |op, obj, *args| obj.send(op, *args) }

vs.

  slf = self
  Functor.new { |op, *args| slf.send(op, *args) }

Not a big deal but there it is. Is there any other reason anyone can
think of that the *obj parameter is acctually needed or more convenient
vs. direct reference in the block itself? If not, is it worth keeping,
or should I just get rid of the *obj parameter altogether?

Settling that issue, I'd like to request that the Functor class be made
part of Ruby's standard library. It is simple, generic and generally
useful --I have had use for it myself on more than a few occasions now
across multiple projects.

Thanks,
T.