How do I inherit subroutines in Perl with 'use base'?

Question

How do I apply 'use base' in Perl to inherit subs from some base module?

I'm used to C++ inheritance mechanics, and all the sites I googled for this caused more confusion then help. I want to do something like the following:

#! /usr/bin/perl
#The base class to inherit from
use strict;
use warnings;

package 'TestBase';

#-------------------------------
sub tbSub
{
    my ($self, $parm) = @_;
    print "\nTestBase: $parm\n";
}

1;

.

#! /usr/bin/perl
#The descendent class
use strict;
use warnings;

use base qw(TestBase);
sub main;
sub mySub;

#-------------------------------
#Entry point...
main();

#---code------------------------
sub main
{
    mySub(1);
    tbSub(2);
    mySub(3);
}

#-------------------------------
sub mySub
{
    my $parm = shift;
    print "\nTester: $parm\n";
}

Perl complains/cannot find tbSub.

Answer 1

The C++ mechnics aren't much different than the Perl mechanics: To use inheritance, you need two classes: the base class and the inheriting class. But you don't have any descendent class.

You are also lacking a constructor. Unlike C++, Perl will not provide a default constructor for you.

Your base class contains a bad syntax error, so I guess you didn't try the code before posting.

Finally, as tsee already observed, you will have to let Perl know whether you want a function call or a method call.

What you really want would look something like this:

my $foo = TestDescendent->new();
$foo->main();


package TestBase;

sub new {
   my $class = shift;
   return bless {}, $class;
}

sub tbSub
{
   my ($self, $parm) = @_;
   print "\nTestBase: $parm\n";
}

package TestDescendent;
use base 'TestBase';

sub main {
    my $self = shift;
    $self->mySub( 1 );
    $self->tbSub( 2 );
    $self->mySub( 3 );
}

sub mySub
{
    my $self = shift;
    my $parm = shift;
    print "\nTester: $parm\n";
}

1;