This might clarify the problem with your question. If your Tinia_CanPwn class isa subclass of your Tinia_CanExtender class, as indicated by your code snippet, then there is no "parent instance". There is only one object (instance) and it is an instance of Tinia_CanPwm, that has inhereted methods from the Tinia_CanExtender class ... not from an instance of that class.

#! perl -slw
use strict;
{
    package Test1; ## This is the parent class which inherits from not
+hing

    sub new{
        my $class = shift;
        return bless { __PACKAGE__ => 'test1 attribute value' }, $clas
+s;
    }
    sub whatAmI{ __PACKAGE__ }; ## No SUPER->whatAmI to call!
                                ## No SUPER->selfRef.
    sub selfRef{ shift }
    1;
}
{
    package Test2;
    our @ISA = 'Test1'; ## A subclass which inherits from Test1.

    sub new{
        my $class = shift;
        my $self = $class->SUPER::new;
        $self->{ __PACKAGE__ } = 'test2 attribute value';
        return bless $self, $class;
    }
    sub whatAmI{ shift->SUPER::whatAmI() . '->' . __PACKAGE__; };
    sub superRef{ shift->SUPER::selfRef; }
    sub selfRef{ shift }
    1;
}
{
    package Test3;
    our @ISA = 'Test2'; ## A sub-subclass which inherits from Test2

    sub new{ 
        my $class = shift;
        my $self = $class->SUPER::new;
        $self->{ __PACKAGE__ } = 'test3 attribute data';
        return bless $self, $class;
    }
    sub whatAmI{ shift->SUPER::whatAmI() . '->' . __PACKAGE__; };
    sub selfRef{ shift }
    sub superRef{ shift->SUPER::selfRef; }
    1;
}
package main;

my $obj = Test3->new;

print 'I am a ', $obj->whatAmI, $/;

print 'My instance id is                          ', $obj, $/;
print 'My instance id in the class is             ', $obj->selfRef, $/
+;
print 'My instance id in my parent class is       ', $obj->superRef, $
+/;
print 'My instance id in my grandparents class is ', $obj->superRef->s
+uperRef, $/;

__END__
P:\test>332433
I am a Test1->Test2->Test3

My instance id is                          Test3=HASH(0x18360e0)

My instance id in the class is             Test3=HASH(0x18360e0)

My instance id in my parent class is       Test3=HASH(0x18360e0)

My instance id in my grandparents class is Test3=HASH(0x18360e0)
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What this attempts to show is that whilst there are three classes providing methods to the instance $obj, the instance handle is the same regardless of which class you are executing a method from.

Hi,

I'd like to have one instance of parent class for communication with serial port. Now child instances beside their own data also contribute to "global" send/receive queue in parent class. Now I have method in parent instance that deals with this queue. Method is inherited into child instances and when I call it - I get reference to child object, but would like to perform operations on parent instance' queue.

Now I would like somehow to get to reference of parent instance from reference of child instance that got into method. How to do this ?

Thanks,

Robert.

You probably don't have an "IS-A" relationship then, but rather a "HAS-A" relationship. One instance of one class (your "parent class") owning a bunch of other specialized classes (your "child class").

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

The answer to the question - the way you have asked it - is NO - it cannot be done - because it does not make any sense.

You need to figure out which process instantiates the parent and the child - That process can be used to connect the two.

If you want to have the latter, you will need to tell the child object who its parent is when you create it. That is the only way.

Inherite (extend) a class exists to get a basic class and add or overwrite some methods. For example, in GUI OO libraries, is very common to have a basic class for controls, that will handle (implement methods) that are common to all the controls, like create, destroy, show, etc... And for each control, like a Button, we have it's own class that Inherite from the basic class, or extends the basic class. Is like tell to class to import the methods and attributes from another class.

What you want is to have a object X that handle some socket data, and another object Y that handle more socket data and also work with X. Soo, create one object X, from your class Tinia_CanExtender, and than create the object Y from the class Tinia_CanPwm. If you want that the object Y has internal reference to X, soo you can paste X as an argument, or set an attribute inside Y.

Take a look in this code:

  my $x = new Tinia_CanExtender() ;
  my $y = new Tinia_CanPwm($x) ;

package Tinia_CanPwm ;

@ISA = qw(Tinia_CanExtender);

sub new {
  my $class = shift ;
  my $this = bless({} , $class) ;
  
  my ( $parent ) = @_ ;
  
  $this->{PARENT} = $parent ;
  
  return $this ;
}

package Tinia_CanExtender ;

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

sub set {
  my $self = shift ;
  my ($state,$set_by) = @_;
  ...
}
[download]