geektron has asked for the wisdom of the Perl Monks concerning the following question:

so i'm trying to subclass Business::OnlinePayment so that my apps can just call the new subclass. here's the ( broken ) constructor code: 
package Unleashed::AuthorizeCard;

use strict;
use base qw/ Business::OnlinePayment /;

sub new {
        my $class = shift;
        my $obj = bless( {}, $class );
        my $realObj = $obj->SUPER::new( "AuthorizeNet"  );

        return $realObj;
}

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I thought that the call to $obj->SUPER::new() would pass the arg ... and it *sort of* does, because here's the error message: 
[ proton ] :: perl -MUnleashed::AuthorizeCard -e '$foo = Unleashed::Au
+thorizeCard->new();'

unknown processor AuthorizeNet (syntax error at (eval 2) line 1, near 
+"use Unleashed::AuthorizeCard="
) at -e line 1

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i know that i could achive similar results with: 

sub new {
    my $obj = Business::OnlinePayment->new( "AuthorizeNet" );
}

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but i thought ( mistakenly? ) that the call to SUPER would do the same thing .....

Replies are listed 'Best First'.
Re: subclass and overridden constructor
by simonm (Vicar) on Dec 03, 2003 at 21:09 UTC
    I think you want something like the below: 
        sub new {
        my $class = shift;
        my $obj = $class->SUPER::new( "AuthorizeNet"  );
        # rebless or do whatever with $obj
        return $obj;
    }

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[d/l]
      that barfs even more .... 
      
unknown processor AuthorizeNet (Can't locate Unleashed/AuthorizeCard/A
+uthorizeNet.pm in @INC

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      and i do have the right mods installed. the test script ( sans subclassing ) works.

      i'm going to have to dig around in Business::OnlinePayment's source, i guess.

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[d/l]
[select]
        Ah, sure enough -- if you look at the source of OnlinePayment.pm you'll see that it's got a very specific approach to subclassing already implemented.

        It might be straightforward to make a package that was a subclass of a specific processor, such as Unleashed::AuthorizeCard::AuthorizeNet inheriting from both your Unleashed::AuthorizeCard and Business::OnlinePayment::AuthorizeNet.

        If you want to dynamically handle whichever processor the end-user selects, you'll probably have to either generate subclasses on the fly, or use delegation rather than inheritance.

        (More generally, this illustrates one of the advantages of well-factored frameworks that use delegation internally; for example, I can imagine a version of Business::OnlinePayment that was divided into separate Transaction and Processor classes, which would allow you to subclass Transaction without worrying which Processor it was connecting to.)

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