Smylers writes:
> I don't find the Perl 5 approach ugly: I actually like it, because it does
> exactly what it looks like it's doing, and doesn't require learning any
> special syntax or keyword.
>
> To have a variable exist beyond outside a sub, you declare it outside that
> sub. To prevent that variable being accessed from anywhere else, you put
> it in a block. It's simple yet provides the power you need, and it's
> completely obvious what's going on.
I disagree that it's simple.
#! /usr/bin/perl -lw
use strict;
print id();
{
my $next = 17; # the first ID is 17
sub id {
return $next++;
}
}
Unfortunately, that completely fails, because the block containing the
declarator hasn't been evaluated the first time you call the sub. So you
get 0 as the answer (because ++ is sufficiently magic). It can be fixed by
making the block a BEGIN block, but suddenly it doesn't seem so simple. It
doesn't help that when you do this in a module, you probably don't see the
problem (because 'use Foo;' effectively does a require in a BEGIN block).
I'd argue that the requirement for BEGIN when you want a so-called-static
variable in your main program (and you define the sub after using it) makes
this approach less than simple.
In addition, I don't think it 'provides the power you need'. With the Perl5
approach, you can't have so-called-static variables scoped to anything other
than (a group of) subroutines -- they can't be scoped to a loop within a
sub, for example.
--
Aaron Crane * GBdirect Ltd.
http://training.gbdirect.co.uk/courses/perl/
