How can I implement generics in Python?

How can I implement generics in Python?

In Python, you can implement generics using the typing module. You can define a generic type using TypeVar.

Can you give me an example of using TypeVar?

Sure! Here's a simple example:

from typing import TypeVar, List

T = TypeVar('T')

def get_first_element(elements: List[T]) -> T:
    return elements[0]

What if I want to restrict the types that can be used with TypeVar?

You can restrict the types by using the bound parameter in TypeVar. For example:

from typing import TypeVar, List

class Animal:
    pass

class Dog(Animal):
    pass

A = TypeVar('A', bound=Animal)

def get_first_animal(animals: List[A]) -> A:
    return animals[0]

Are there any limitations to using generics in Python?

Yes, Python's generics are not as strict as in some other languages. Type checking is mostly done at runtime, so you won't get compile-time errors for type mismatches.