http://www.perlmonks.org?node_id=48891
Ovid has asked for the wisdom of the Perl Monks concerning the following question:

I have a problem that I'm not sure of the best approach to take. I have a base class that has two sub-classes that inherit from it:
[base] / \ / \ [subclass A] [subclass B]
B has similar functionality to A. A returns some data, B writes the data to a file, but in a different format than the data returned from A. Under some circumstances, the data written to the file from B is in the exact same format as the data returned from A.

However, I don't want B to inherit A's methods as I don't want the user accessing them from the object. In other words, I might have

my $object = A->new; $object->someWeirdMethod;
What I don't want is
my $object = B->new; $object->someWeirdMethod;
But that happens if I inherit from A, unless I write a bunch of methods to trap those calls and let the user know they shouldn't do that.

The alternative seems to be having B instantiate an A object, but having subclasses instatiating instances of each other strikes me as problematic. I keep up that habit and I might start winding up with circular references that I'll have to explicitly destroy.

Summary: two options that I see:

  1. Have B inherit from A, but don't let people call A's methods from B.
  2. Have B instantiate an instance of A. I like this better, but somehow it feels wrong.
Any pointers? I don't do a lot of OO programming and I'd appreciate feedback as to the best approach to take.

Cheers,
Ovid

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