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Postings from June 2001
Peter Scott wrote: > What's wrong with multiple inheritance? You have to create a whole load of extra classes whose only purpose is to define a list of superclasses. Compare: bless $self, qw(Employed Male); with package Employed_Male; @ISA=qw(Employed Male); # multiple inheritance ... bless $self, "Employed_Male"; Allowing C<bless> and C<ref> to use lists allows me to be slightly more Lazy. In bigger hierarchies, the benefits are greater because the number of possible leaf classes is greater. (Imagine Employed as subclasses of FullTime and PartTime; then add in race, ethnicity, ...) Some people would argue that these things are attributes, not base classes; but those same people would argue that multiple inheritance is bad. I'm not objecting to multiple inheritance: I just saying that its a waste of effort to create classes that don't add any new details. If the class that combines multiple superclasses adds unique behaviour/data to that combination, then multiple inheritance is the correct solution. When all you are doing is saying that an object has 2 classes then forcing the extra work is just a waste of time. Dave.