From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-09-20T00:34:48+09:00
Subject: Re: help with tricky proc/binding issue

On Mon, 19 Sep 2005, Yukihiro Matsumoto wrote:

> Hi,
>
> In message "Re: help with tricky proc/binding issue"
>    on Mon, 19 Sep 2005 23:42:12 +0900, "Ara.T.Howard" <Ara.T.Howard@noaa.gov> writes:
>
> |i'm trying to be able to define a proc that can be called in the context of
> |self, eg:
> |
> |   block = lambda{ p 42 }
> |   an_obj.instance_eval &block
> |
> |but which can also be called with arguments, for example (imaginary ruby):
>
> I understand what you want.  But I haven't come up with a good name
> for the function yet.

maybe

   class Object
     def evaluate(*args, &block)
       ...
     end
   end

??

another option would be to turn the problem inside out and do something like

   l = lambda{ p x }
   l.self = obj
   l.call


this is what i have so far:

   [ahoward@localhost ~]$ cat a.rb
   class Object
     def evaluate(*a, &b)
       m = "____eval____#{ rand(65536) }____"
       klass = Class === self ? self : self::class
       klass.module_eval{ define_method m, &b }
       begin
         send m, *a
       ensure
         klass.module_eval{ remove_method m }
       end
     end
   end

   class C
     def y
       42
     end
   end

   b = lambda{|x| p [x, y, self]}

   c = C::new
   x = 42
   c.evaluate(x, &b)  #=> [42, 42, #<C:0xb7f2f5c0>]


   [ahoward@localhost ~]$ ruby a.rb
   [42, 42, #<C:0xb7f1b5c0>]


thoughts?

-a
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