What methods can be used to implement dependency injection between classes in software?

Dependency Injection (DI) is a pattern that allows passing dependencies (objects, services) into a class from outside rather than creating them inside the class. In Python, this can be implemented in several ways:

1. Constructor Injection Dependencies are passed through the class constructor:

class Service:
    pass

class Client:
    def __init__(self, service: Service):
        self.service = service

service = Service()
client = Client(service)

2. Setter Injection Dependencies are set through methods:

class Client:
    def set_service(self, service: Service):
        self.service = service

client = Client()
client.set_service(service)

3. Property Injection Dependencies are assigned directly to attributes:

client = Client()
client.service = service

4. Using DI frameworks For example, dependency_injector — a library for managing dependencies.

The main idea is to separate the creation of dependencies from their use, which facilitates testing and maintenance of the code.