As a concrete example of this:

unless (caller() =~ /main/) {
    My::Standalone->run();
} else {
    @My::Standalone::EXPORT = qw[run];
}
package My::Standalone;
use strict;
use warnings;
use Exporter;

our @ISA = qw(Exporter);

sub run {
    my($self) = shift || caller();
    print "See, I do something\n";
}

1;
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You can then call this with any of the following:

• perl My/Standalone.pm
• perl -MMy::Standalone -e"run();"

or include it in a script:

#!perl
use strict;
use warnings;
use My::Standalone;

print "Do something\n";
run(); # Call the run function
exit;
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