Konstruktorinjektálás

Konstruktorinjektálás, also known as constructor injection, is a form of dependency injection where the dependencies of a class are provided through its constructor. Instead of a class creating its own dependencies or fetching them from a global source, these dependencies are passed as arguments to the class's constructor during its instantiation. This approach promotes loose coupling between classes and makes them easier to test and manage.

When a class relies on other objects (its dependencies) to perform its functions, these dependencies must be made available to the class. In constructor injection, this is achieved by defining constructor parameters that accept instances of the required dependency types. The responsibility of creating and providing these dependency instances then falls to an external entity, typically a dependency injection container or framework, or manually by the developer in simpler scenarios.

The primary benefits of constructor injection include enhanced testability, as mock or stub versions of dependencies can be easily passed to the constructor during unit testing. It also leads to more maintainable code by clearly defining a class's requirements and reducing hidden dependencies. Furthermore, it enforces that a class is fully initialized with all its necessary collaborators upon creation, preventing potential null reference errors later in its lifecycle. This method is widely adopted in modern software development practices.