Re (tilly) 1: oo perl - using the super-class

Perl has a standard way of doing it already.

Create your sub-classes TransactionA and TransactionB, put Transaction in @ISA for each. Have your Transaction constructor respect inheritance by using the two-argument form of bless. For instance:

sub new {
    my $class = shift;
    my $self = {};
    %$self = @_; # Whatever fits - this is just and example
    return bless($self, $class);
}
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And now your end code will be able to say:

my $trans = new TransactionA;
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and it will all work.

For more take a look at this tutorial.

Comment on Re (tilly) 1: oo perl - using the super-class Select or Download Code

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RE: Re (tilly) 1: oo perl - using the super-class by kevinlyda (Initiate) on Oct 03, 2000 at 18:50 UTC
hm, no, that's exactly what i don't want. i never want to have the main code say: `$trans = new TransactionA` [download] i want to say `$trans = new Transaction($request);` [download] and have $trans be an instance of TransactionA or TransactionB. i'm not up on oo terminology, but i think what i really want is a TransactionFactory class. again, i'm not sure but the above describes what i'm looking for. i'm just wondering if it's a good thing to look for or is there a better design to use?	[reply] [d/l] [select]
RE: RE: Re (tilly) 1: oo perl - using the super-class by merlyn (Sage) on Oct 03, 2000 at 18:52 UTC
Your original code was fine. Just make sure that neither of your two specific types of transaction inherit from the generic transaction, or you're toast on the `new` routine! -- Randal L. Schwartz, Perl hacker	[reply]
RE (tilly) 3: oo perl - using the super-class by tilly (Archbishop) on Oct 03, 2000 at 18:53 UTC
Well you can do whatever you want with the two argument form of bless, but you will break inheritance. OTOH containment (ie making one property of an object be a member of a different class) is usually cleaner than inheritance anyways, but if you play this kind of game you really should document it to avoid potential grief for someone else.	[reply]