> -----Original Message-----
> From: Jonathan Scott Duff [mailto:[EMAIL PROTECTED]
> On Thu, Oct 02, 2003 at 11:39:20AM +0100, Dave Mitchell wrote:
> > On Thu, Oct 02, 2003 at 04:15:06AM -0600, Luke Palmer wrote:
> > > So the question is: What happens when indexof isn't on the call chain,
> > > but that inner closure is?
> >
> > But how can the inner closure be called if not via indexof?
>
> I believe that's exactly what Luke's original example was
> illustrating.
>
> On Thu, Oct 02, 2003 at 01:59:26AM -0600, Luke Palmer wrote:
> > So, I must ask, what does this do:
> >
> > sub foo() {
> > return my $self = {
> > print "Block";
> > return $self;
> > }
> > }
>
> foo() returns a closure that contains code that returns from the foo()
> subroutine (the line that says "return $self") When that closure is
> then called ...
>
> > my $block = foo;
> > print "Main";
> > $block();
>
> ... foo() is no longer executing.
>
> > That is, the block returns from a function that's not currently
> > executing.
> >
> > Will the output be: a)
> >
> > Can't 'return' from closure Block
> >
> > b)
> >
> > Main
> > Block
> > Can't 'return' from closure Block
> >
> > (just like (a) but runtime)
> > c)
> >
> > Main
> > Block
> >
> > (the block's return returns from the main program, or whatever function
> > is currently executing)
> >
> > d)
> >
> > Main
> > Block
> > Main
> > Block
> > Main
> > Block
> > ...
> >
> > (the block closes over the function's return continuation)
>
> I would expect (a) to happen, but (d) has some interesting
> possibilities.
I hope not. Otherwise the ability to use anonymous blocks would be severely
impaired.
If there's a list of keywords that can't be used in anonymous blocks, that's
a pretty severe limitation.
And really, is this any worse than an anonymous block that throws
exceptions?
Speaking to the practical side, I have written code that has to disentangle
itself from the failure of a complex startup sequence. I'd love to be able
to build a dynamic exit sequence. (In fact, being able to do <C>&block .=
{ more_stuff(); };</C> is way up on my list...)
=Austin
