Three ways of implementing dependency injection with Autofac.

Autofac is an open-source dependency injection container that helps manage object dependencies in our application. It offers various methods for dependency injection, and here are three commonly used options:

1. Constructor Injection is the most common way of dependency injection, where dependencies are declared as parameters in the class’s constructor. Autofac automatically resolves these parameters and injects the corresponding dependencies. The advantage of using Constructor Injection is that it ensures dependencies are injected when the class is instantiated, preventing potential null reference exceptions when using the dependencies.
2. Property Injection: Declaring a public property in a class and marking it with a property injection attribute (such as [Autowired]). Autofac will use reflection to resolve these attributes and inject the corresponding dependency objects into the marked properties. Compared to constructor injection, the advantage of property injection is that dependencies can be injected after the class is instantiated, making it more flexible. However, it also increases the risk of null references, so it is necessary to check for non-null before using the dependency objects.
3. Method injection: declaring a public method in a class and marking it with method injection attributes (such as [Inject]). Autofac will resolve these attributes through reflection and call the methods when needed, injecting the necessary dependency objects as method parameters. Method injection, similar to property injection, allows for dependency injection after class instantiation, but is more flexible as it can be done as needed.

In summary, Autofac offers three common dependency injection methods: constructor injection, property injection, and method injection. The specific choice depends on the needs and design style of the application.