From: Mathieu Bouchard <matju@...>
Date: 2001-10-06T13:12:45+09:00
Subject: [ruby-talk:22150] Re: Marshal won't dump a Proc

On Thu, 4 Oct 2001, HarryO wrote:

> In article <Pine.LNX.4.21.0110031855001.27045-100000@relayer>, "Mathieu
> Bouchard" <matju@sympatico.ca> wrote:
> If I understand what you're getting at, the extension you've made to the
> kernel module allows me to do either of these ...
>    p1 = proc { puts "hello, world" }
>    p2 = proc %{ puts "hello, world" }
> Is that right?

yes.

> Assuming you've read my long-winded reply, explaining what I'm trying
> to achieve, I could do something like ...
>    fibonacci = Stream.new([1, 1]) %{ |s, i| s[i - 2] + s[i - 1] }
On Thu, 4 Oct 2001, HarryO wrote:
>    fibonacci = Stream.new([1, 1]) proc %{ |s, i| s[i - 2] + s[i - 1] }

neither is correct. The trick only works with proc. but you may use this
identity:

	foo(a,b,c) { d }

is functionally equivalent to:

	foo a,b,c,&proc { d }

oh, and by the way, if you need to access outer-local scopes, you can't
use the percent trick: it won't pick up the correct scope (not even the
correct self). You'd need the "binding.caller" feature, which is in a RCR
that I submitted some time ago; as a substitute using current means, you'd
have to write:

	foo a,b,c,proc binding, %{ d }

in Ruby 1.6, or:

	foo a,b,c,proc(binding, %{ d })

in Ruby 1.7 (which is slightly more cumbersome). Alternately you could get
away with:

	foo a,b,c,proc(%{ d }){}

where you use the empty proc as a binding (iirc).

________________________________________________________________
Mathieu Bouchard                   http://hostname.2y.net/~matju