[Python-Dev] Things to Know About Super

average dreamingforward at gmail.com
Tue Sep 2 06:02:30 CEST 2008

It seems that the frustration with super revolves around how Python
currently conflates (as well as many users) two very different types
of inheritance, both "is-a" and "has-a" (or compositional)
inheritance.  Unfortunately, Python assists this confusion because the
language doesn't provide a distinct enough way to differentiate
between them.

For the former (i.e. is-a inheritance), users should not have to
explicitly make a call to the super class (via super() or
otherwise)--this should be automatic for every method held in common
so as to guarantee the invariants of the simpler class.  For this type
of inheritance it makes more sense to be explicit about *bypassing* a
call to the parent class--IF necessary (perhaps to take advantage of
an optimization available only in the subclass)--rather than explicit
about *making* one.  This would remove many of the bugs, misuses, and
frustrations with super().  No more ambiguity and confusion because
the language now guarantees certain behavior.  Super() would then be
limited to cooperative mixin classes; for all others, explicit naming
of the class would be required.  But perhaps that there is some
language abstraction that has yet to be fully invented that would tie
it all together nicely.

By the way, regarding your trait implementation, it may be worthwhile
revisiting the discussion surrounding the Prothon language discussed a
few years ago on comp.lang.python which got rid of classes and
metaclasses and replaced them with prototypes.



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