#######

package Modulino::A;

use strict;
use Exporter qw(import);

# buy() will be useful to others...
our @EXPORT_OK = qw( buy );

__PACKAGE__->run(@ARGV) unless caller;

sub run {
    my ($class, $arg) = (@_);
    $class->perform_modulino_specific_stuff;
    buy($arg);
}

sub perform_modulino_specific_stuff {
    my $class = shift;
    print "[special stuff for Modulino::As]\n";
}

sub buy {
    print "[very useful purchasing algorithm to buy ", $_[0], "]\n";
}

#######

##</code><code>##

package Modulino::B;
use base qw( Modulino::A );

use strict;

unless(caller) {
    no strict 'refs';
    # "override" Modulino::A::buy with Modulino::B::buy...
    *{ "Modulino::A::buy" } = \&buy;
    # re-use Modulino::A::run...
    __PACKAGE__->run(@ARGV);
}

sub perform_modulino_specific_stuff {
    my $class = shift;
    print "[special stuff for Modulino::Bs]\n";
}

sub buy { print "[alternative way to buy ", $_[0], "]\n" }

#######

##</code><code>##

# Demonstrate use of Modulino::A's exported functions...
$ perl -MModulinoA=buy -le 'buy("camels and onions")'

#######