[Python-ideas] A (meta)class algebra (original) (raw)

Thomas Kluyver thomas at kluyver.me.uk
Thu Feb 12 19:35:23 CET 2015

On 12 February 2015 at 05:42, Martin Teichmann <lkb.teichmann at gmail.com> wrote:

With my addition, one could simply add a method to MetaRegistrar:

def add(self, other): class Combination(self, other): pass return Combination

Having recently had to refactor some code in IPython which used multiple inheritance and metaclasses, -1 to this idea.

  1. More magic around combining metaclasses would make it harder to follow what's going on. Explicit (this has a metaclass which is a combination of two other metaclasses) is better than implicit (this has a metaclass which can combine itself with other metaclasses found from the MRO).
  2. I want it to be hard for people to write multiple-inheriting code with multiple metaclasses. That code is most likely going to be a nightmare for anyone else to understand, so I want the person creating it to stop and think if they can do it a different way, like using composition instead of inheritance.

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