At 18:43 -0500 2000/10/02, David L. Nicol wrote:
>Hmm. C<no scope> could be implemented in terms of the rfc 340 C<with> like
>so:
>
> $scope_out_here = with;
> if ($ints) {
> with $scope_out_here {use integer}
> };
>
>C<caller> is about subroutine calls.
Interesting! I have a few questions (meandering thoughts) though <g>
The example in the RFC gives:
sub A{
my $A = shift;
return with;
};
$context1 = A(3);
print "$context1"; # something like CONTEXT(0XF0GD0G)
print "$A" with $context1; # prints 3
with $context1{print "$A"}; # same thing
This implies that &A is now something akin to a closure, correct?
That is to say, the meaning of C<my $A> becomes changed by the
presence of C<return with;> so that $A is something in between a
lexical scoped to &A and a lexical scoped around &A ({ my $A; sub A
{} }). $A is held in existence by the presence of the context
object. Presumably $A would 'go out of scope' and be destroyed at
the same time as the associated context object? This worries me, but
I admit it's neat ;)
What is more worrying to me is this: with a C<no scope;> pragma, you
can only go up /your/ scope. Consider this:
package Nasty;
my $context;
{
package Unsuspecting_Package;
$context = with;
}
use integer with $context;
Spooky action at a distance to be sure! Also, integer (and others)
is a compile time issue. Using C<no scope> can be easily (it would
appear) implemented for compile-time since it's merely another
pragma. On the other hand, C<with> strikes me as more of a run-time
beast. (at this point, I'm not sure if I have any idea of what I'm
talking about, so excuse me if this has digressed into rambling :)
So I like the idea of C<with>, but am not sure it is compeltely
suitable for invoking pragmata such as integer.
.greg
--
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<click>
"Release to detonate."
