Mixin vs inheritance

Question

What is the difference between a mixin and inheritance?

Answer 1

Mixins are vastly used in a more "plugin" like manner.

They are the same but in a different context each one of them. Usually when we talk about inheritance we are talking about SINGLE inheritance, and a mixin is a construct that allows MULTIPLE inheritance.

This is a language construct that is highly controversial in the OOP world because of:

• The ambiguity that it must be resolved
• A lot of the time "mixin" classes don't work on its own, and may conflict with other mixins
• It can result in a "diamond inheritance problem", where two super classes can inherit from the same class

But that aside, is a powerful construct that's used in various languages and frameworks, some examples are:

• Django

  • https://github.com/django/django/blob/98126cdfaf632abc8f0b5e65910e46a4eedc4641/django/views/generic/list.py#L194

  • https://docs.djangoproject.com/en/3.1/topics/class-based-views/mixins/

• Typescript
  • https://www.typescriptlang.org/docs/handbook/mixins.html
  • https://vincit.github.io/objection.js/guide/plugins.html#_3rd-party-plugins