Abstract-Base-Class

ABCMeta

I don't do a lot of OOP currently, but I have been on a few heavy OOP projects and this ABCMeta and abstractmethod from abc would've been super nice to know about!

If you are creating a library with classes that you expect your users to extend, but you want to ensure that any extension has explicit methods defined then this is for you!.

from abc import ABCMeta, abstractmethod
class Family(metaclass=ABCMeta):
    @abstractmethod
    def get_dad(self):
        """Any extension of the Family class must implement a `get_dad` method"""

class MyFamily(Family):
    pass

If I try to instantiate MyFamily I will not be allowed:

❯ my_fam = MyFamily()
╭─────────────────────────────── Traceback (most recent call last) ────────────────────────────────╮
│ <ipython-input-8-ecb8e21ce815>:1 in <module>                                                     │
╰──────────────────────────────────────────────────────────────────────────────────────────────────╯
TypeError: Can't instantiate abstract class MyFamily with abstract methods get_dad

In order for me to extend Family I have to implement the method get_dad

class MyFamily(Family):
    def get_dad(self):
        return "Me"

Now everything works as expected and I can sleep well knowing no one can extend my base class without creating methods I know they need.

my_fam = MyFamily()

my_fam.get_dad()
'Me'