Extending an Object in Perl - perl

Question

I've got a base object called RuleObject and an object that inherits from that called RuleObjectString. I have a new method in RuleObjectString that I want to call in my code that uses that object. But I get the error. 'Can't locate object method "compare" via package "RuleObject" at ./testobject.pl line 10.' But I'm not creating a RuleObject. I'm creating a RuleObjectString. What am I doing wrong here?
testobject.pl
1 #! /usr/bin/perl
2
3 use strict;
4
5 use RuleObjectString;
6
7 my $s = RuleObjectString->new();
8 $s->value('stuff goes here');
9
10 if ($s->compare('stuff')){
11 print "MATCH!\n";
12 }else{
13 print "no match :(\n";
14 }
RuleObject.pm
package RuleObject;
our #ISA = qw/Exporter/;
our #EXPORT = qw/new/;
use strict;
sub new{
my $class = shift;
my $self;
$self->{value} = undef;
bless $self;
return $self;
}
sub value{
my $self = shift;
my $value = shift;
if ($value){
$self->{value} = $value;
}else{
return $self->{value};
}
}
RuleObjectString.pm
package RuleObjectString;
our #ISA = qw/RuleObject/;
our #EXPORT = qw/compare/;
use strict;
sub compare{
my $self = shift;
my $compareto = shift;
return $self->value() =~ /$compareto/;
}

Answer 1

I think jmcneirney is on the right track. In your RuleObject constructor, you say
bless $self;
which is the same as
bless $self, __PACKAGE__;
or
bless $self, 'RuleObject'
but what you want is for the object to blessed as a RuleObjectString. So what you want to do is say
bless $self, $class
Now
RuleObject->new()
RuleObjectString->new()
will both call the same constructor, but the object returned by the first call will be blessed as a RuleObject and the second object will be blessed as a RuleObjectString.

Answer 2

This is 2012, so you should consider using proper OOP solutions instead of reinventing the wheel all over again.
By using Moose, the solution would look something like this (untested):
RuleObject.pm
package RuleObject;
use Moose;
has 'value' => ( isa => 'Str', is => 'rw', required => 0, default => '' );
1;
RuleObjectString.pm
package RuleObjectString;
use Moose;
extends 'RuleObject';
sub compare {
my $self = shift;
my $compareto = shift;
return $self->value =~ /$compareto/;
}
1;
Simple! :)

Answer 3

Try dumping the object and see what it is.
print Dumper( $s )
It's going to be a RuleObject.
You might need to define a new() in RuleObjectString
and have it call Super::new().