antioch has asked for the wisdom of the Perl Monks concerning the following question:

Hi,

I'm working on a script and at one point the script calls up a subroutine located in an external file. In that external subroutine, it tries to print a variable that is located in the original script file. I can do this fine but I'm working in Perl Tk where it always asks you to use the "my" function to declare variables. That little function required in Perl/Tk causes my problem and I was wondering if anyone knew a way around it. Heres some code example to make this a little easier to understand: 
require "external_subs.txt";

my $a = 1;
my $b = blue;

  if($a == 1) {
        &numbers
      } else{ die;

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That would be the main script file and this would be the external file, "external_subs.txt" : 
sub numbers {
        print "$b";
     }

1;

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If you take out the 'my' fuctions, the whole thing works fine as you can see. But put them in and your stuck in my situation. =\

Also I'm using ActiveState 5.6.1 on Windows XP. Any help would be greatly appreciated! Thanks.

Replies are listed 'Best First'.
Re: Passing Variables to External Subroutines (Perl/Tk)
by NetWallah (Canon) on Jun 15, 2004 at 05:22 UTC
    "use warnings;" gives a clue as to the cause of this behaviour.

    The problem is fixed by using
    our $b = 'blue';
    instead of "my".

    "An our declaration declares a global variable that will be visible across its entire lexical scope, even across package boundaries. "

    Offense, like beauty, is in the eye of the beholder, and a fantasy.
    By guaranteeing freedom of expression, the First Amendment also guarantees offense.

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Re: Passing Variables to External Subroutines (Perl/Tk)
by Plankton (Vicar) on Jun 15, 2004 at 05:18 UTC
    Oooh! Ohhh! I always wanted to say this ...

    You shoud use strict.

    Also you might not want to use the variable names $a and $b because of how sort works.
    Update with Example: 
    Plankton@Chum_Bucket:~/perl/perlmonks> cat scritp.pl
#!/usr/local/bin/perl
use strict;
require "ex.txt";
my $bb = "blue\n";
&numbers ( $bb );
Plankton@Chum_Bucket:~/perl/perlmonks> cat ex.txt
sub numbers {
        my $v = shift;
        print "$v"
     }
 
1;

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    Plankton: 1% Evil, 99% Hot Gas.
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Re: Passing Variables to External Subroutines (Perl/Tk)
by matija (Priest) on Jun 15, 2004 at 05:23 UTC
    Maybe I'm missing something, but what's wrong with saying: 
      &numbers($b);

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    in the main script and 
    sub numbers {
     my $b=shift @_;
        print "$b";
     }

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    in your external_subs.txt? That way, it will work with my, and use strict and all the rest of the stuff that will save you from having your brain fried once your script gets a bit more complex.
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Re: Passing Variables to External Subroutines (Perl/Tk)
by antioch (Sexton) on Jun 15, 2004 at 13:08 UTC
    Ah I see, all of your guys solutions work. I guess it just comes down to preference in some situations. Also I was just using 'a' and 'b' as an example so there wouldnt be a problem, but thanks for lookin out Plankton.

    I didn't think it would be that easy but I guess it was, thanks a lot for all the help! =)

    -antioch
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