From: Chad Perrin <perrin@...>
Date: 2006-08-01T08:07:01+09:00
Subject: Re: I thought this was the one that worked?

On Tue, Aug 01, 2006 at 07:54:33AM +0900, Jacob Fugal wrote:
> On 7/31/06, Chad Perrin <perrin@apotheon.com> wrote:
> >On Tue, Aug 01, 2006 at 07:05:31AM +0900, Logan Capaldo wrote:
> >> I'm not sure I understand your question. All blocks (by blocks I mean
> >> do / end and { } ) are (lexically scoped) closures.
> >
> >I'll use a Perl example:
> >
> >sub foo {
> >  my $bar = 1;
> >  return sub { print ++$bar };
> >}
> >
> >my $baz = foo();
> >
> >Voila.  $baz contains a lexical closure.  This is the case because the
> >return value from foo() was lexically "closed" by virtue of $bar going
> >out of scope, but its value still being accessible via the coderef
> >returned from foo() and assigned to $baz.
> 
> How is this different from:
> 
>  def foo
>    bar = 1
>    return proc{ bar += 1; puts bar }
>  end
> 
>  begin
>    puts bar
>  rescue Exception => e
>    puts e
>  end
>  # => undefined local variable or method `bar' for main:Object
> 
>  baz = foo
>  baz.call # => 2
>  baz.call # => 3
>  baz.call # => 4

Who said it's different?  I'm just asking about the foregoing statement
that all blocks are closures (which strikes me as improbable).  That's
like saying that this will generate a closure (which it won't):

sub foo {
  return sub { my $bar = 1; print ++$bar };
}

-- 
CCD CopyWrite Chad Perrin [ http://ccd.apotheon.org ]
print substr("Just another Perl hacker", 0, -2);