From: Jean-Hugues ROBERT <jean_hugues_robert@...>
Date: 2004-05-03T13:45:45+09:00
Subject: Re: Why no Proc##[]=() ? Why no Proc##replace() ?

At 22:10 02/05/2004 +0900, you wrote:
>On Sun, May 02, 2004 at 05:18:09PM +0900, Jean-Hugues ROBERT wrote:
> > There are other ways to do this of course, without replace:
> >   p = proc { @x ||= long_method }
> > or (needed if result can be nil)
> >   p = proc { @x = long_method unless defined? @x; @x }
>
>It seems to me that you're assuming @x is an instance variable of the
>Proc object, which it is not:

You are right, I was wrong. I believed @x was an instance variable
of Proc object.

>def foo; 1 end
>#   =>nil
>p = proc { @x ||= foo }
>#   =>#<Proc:0x401f9cec@(irb):2>
>@x
>#   => (irb):3: warning: instance variable @x not initialized
>#   =>nil
>p[]
>#   =>1
>@x
>#   =>1

Hum... OK. I am wrong. How can I have a block variable that survives
multiple across multiple invocation ?

I had tried with a local variable, but that did not work. So I tried
with an instance variable, and it seemed to work (but does not,
because I was wrong assuming self was the Proc object, whereas in fact
it is the enclosing method's self, which makes sense BTW).

BTW: Where can I save the result of long_method, if neither in a
class variable, nor in a local variable ?

Is there such a thing that "current_block()" or whatever method
that tells me what the Proc object is ?

I guess my example with self.replace { mutated_block } was wrong too
(it was not supposed to work anyways because replace is not there
for Proc/s). So... How can a block remember things ?

Yours,

Jean-Hugues

>--
>Running Debian GNU/Linux Sid (unstable)
>batsman dot geo at yahoo dot com
>
>'Ooohh.. "FreeBSD is faster over loopback, when compared to Linux
>over the wire". Film at 11.'
>         -- Linus Torvalds

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