How to share/export a global variable between two different perl scripts?

Question

How do we share or export a global variable between two different perl scripts.

Here is the situation:

first.pl

#!/usr/bin/perl
use strict;
our (@a, @b);
.........

second.pl

#!/usr/bin/perl
use strict;
require first.pl;

I want to use global variable (@a, @b) declared in first.pl

Also,suppose there's a variable in second perl file same as first perl file. But I want to use first file's variable. How to achieve this?

Answer 1

In general, when you are working with multiple files, and importing variables or subroutines between them, you will find that requiring files ends up getting a bit complicated as your project grows. This is due to everything sharing a common namespace, but with some variables declared in some files but not others.

The usual way this is resolved in Perl is to create modules, and then import from those modules. In this case:

#!/usr/bin/perl

package My::Module;  # saved as My/Module.pm
use strict;
use warnings;

use Exporter;
our @ISA = 'Exporter';
our @EXPORT = qw(@a @b);

our (@a, @b);

@a = 1..3;
@b = "a".."c";

and then to use the module:

#!/usr/bin/perl

use strict;
use warnings;

use My::Module;  # imports / declares the two variables

print @a;
print @b;

That use line actually means:

BEGIN {
    require "My/Module.pm";
    My::Module->import();
}

The import method comes from Exporter. When it is called, it will export the variables in the @EXPORT array into the calling code.

Looking at the documentation for Exporter and perlmod should give you a starting point.

Answer 2

They will share global variables, yes. Are you seeing some problem with that?

Example:

first.pl:

#!/usr/bin/perl

use strict;
use warnings;

our (@a, @b);

@a = 1..3;
@b = "a".."c";

second.pl:

#!/usr/bin/perl

use strict;
use warnings;

require "first.pl";

our (@a,@b);
print @a;
print @b;

Giving:

$ perl second.pl
123abc

Answer 3

Cant you use package and export the variable?