Delegation (object-oriented programming)

Delegation, in object-oriented programming, is a design pattern or language feature where an object, instead of performing a certain action itself, forwards the responsibility for that action to another associated object. The delegating object is essentially saying, "I can handle this request, but I'm going to let another object, my delegate, actually do the work."

The core idea behind delegation is code reuse and decoupling. It promotes loose coupling between objects because the delegating object doesn't need to know how the delegate performs the action, only that it can perform the action. This allows for more flexible and maintainable systems. The delegating object only needs to maintain a reference to the delegate.

Delegation differs from inheritance. Inheritance establishes an "is-a" relationship (e.g., a car is a vehicle), whereas delegation establishes a "has-a" or "uses-a" relationship (e.g., a car has a steering wheel or uses a fuel injector). With inheritance, the subclass inherits the methods and properties of the superclass. With delegation, the object explicitly forwards calls to a delegate object.

There are various motivations for using delegation:

• Avoiding Inheritance Issues: Delegation can be used to avoid the rigid structure and potential problems of multiple inheritance.

• Flexibility: Delegation allows for changing the behavior of an object at runtime by simply changing its delegate.

• Code Reusability: Delegation allows an object to reuse the functionality of another object without inheriting its entire interface or class hierarchy.

• Interface Segregation Principle: Delegation promotes the Interface Segregation Principle by allowing objects to implement only the interfaces they actually need, delegating other functionality to specialized objects.

In essence, delegation offers a powerful mechanism for composing objects and managing responsibilities in a flexible and decoupled manner.