What are some examples of metaclasses in Python?

What are some examples of metaclasses in Python?

Metaclasses in Python are classes of classes that define how a class behaves. For example, you can create a metaclass to enforce certain rules on class attributes.

Can you show me a simple example of a metaclass?

Sure! Here's a simple example:

class Meta(type):
    def __new__(cls, name, bases, attrs):
        attrs['greeting'] = 'Hello!'
        return super().__new__(cls, name, bases, attrs)

class MyClass(metaclass=Meta):
    pass

print(MyClass.greeting)  # Output: Hello!

What happens if I don't use a metaclass?

If you don't specify a metaclass, Python uses the default metaclass, which is type. Your class will still work, but you won't have the ability to customize its creation.

Are there any real-world applications of metaclasses?

Yes, metaclasses are often used in frameworks like Django for ORM models, where they help define how models behave and interact with the database.