Subclassing Python dictionary to override __setitem__

Question

I am building a class which subclasses dict, and overrides __setitem__. I would like to be certain that my method will be called in all instances w

Answer 1

What is your use-case for subclassing dict?

You don't need to do this to implement a dict-like object, and it might be simpler in your case to write an ordinary class, then add support for the required subset of the dict interface.

The best way to accomplish what you're after is probably the MutableMapping abstract base class. PEP 3119 -- Introducing Abstract Base Classes

This will also help you anser the question "Are there any other methods which I need to override?". You will need to override all the abstract methods. For MutableMapping: Abstract methods include setitem, delitem. Concrete methods include pop, popitem, clear, update.