What are metaclasses in Python and how do they work?

What are metaclasses in Python and how do they work?

Metaclasses are classes of classes in Python. They define how a class behaves. A class is an instance of a metaclass.

Can you give me an example of a metaclass?

Sure! Here's a simple metaclass that modifies class creation by adding a custom attribute:

class MyMeta(type):
    def __new__(cls, name, bases, attrs):
        attrs['custom_attr'] = 'This is a custom attribute'
        return super().__new__(cls, name, bases, attrs)

class MyClass(metaclass=MyMeta):
    pass

print(MyClass.custom_attr)  # Output: This is a custom attribute

What are some practical uses of metaclasses?

Metaclasses can be used for enforcing coding standards, automatic registration of classes, or even implementing singleton patterns.

Are there any downsides to using metaclasses?

Yes, metaclasses can make code harder to understand and debug. They should be used judiciously and only when necessary.