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2001 Dec 30 17:07

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Re: [vox-tech] Perl: Can I declare $main::variable within a subroutine,
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Re: [vox-tech] Perl: Can I declare $main::variable within a subroutine, while using strict?



also, beware of "closures".  if you're programming in modperl for
instance, your code will be subjected to "closure" behavior, which can
make things odd.

So, use the suggestion below ALWAYS.  The var is always $PACKAGE::var,
$main::tmp in your case.

The specific thing that'll screw you up in closures is making the
assumption that $main:: is always $main::... ie..

use strict;
use vars qw/$tmp/;
print $tmp;

sub blah {
print $main::tmp;
}

this code (baring any stupid typos) would compile and run just fine in
most cases... but in the closure case, the first $tmp _MAY_ wind up in
some other package -- $tmp would not necessarily be $main::tmp.

There's more about this at the modperl site, but there are other places
it'll grab you rather than just modperl.  the important thing is if you
start doing variables outside your use strict scope, make sure you always
reference the variable by the full name you've given it.

I'd also suggest you adopt a $mainvar:: (or perhaps use a hash reference
like $mainvar::href->{myvar}) style so you never accidentally walk over a
variable name.  Globals are dangerous!

On Tue, Aug 07, 2001 at 08:48:49AM -0400, Mike Simons wrote:
> yes,
> 
> --- zap.pl-orig Tue Aug  7 00:55:12 2001
> +++ zap.pl      Tue Aug  7 00:54:54 2001
> @@ -5,3 +5,3 @@
>  
> -print "$tmp\n";
> +print "$main::tmp\n";
>  
> 
> On Mon, Aug 06, 2001 at 02:46:33PM -0500, Jay Strauss wrote:
> > > cat ./tmp
> > #!/usr/bin/perl -w
> > use strict;
> > 
> > create();
> > 
> > print "$tmp\n";
> > 
> > sub create {
> > 
> >         $main::tmp = 1;
> > }
> > 
> > > ./tmp
> > Global symbol "$tmp" requires explicit package name at ./tmp line 6.
> > Execution of ./tmp aborted due to compilation errors.

-- 
Ted Deppner
http://www.psyber.com/~ted/


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