DelegationAndComposition

From APIDesign

Delegation and composition is one way to achieve code reuse. In classical object oriented languages it is sort of second class citizen, but that does not mean it is less powerful. Quite opposite.

While reuse by subclassing often leads to accidental reuse (as demonstrated in ClarityOfAccessModifiers essay). The delegation and composition is as powerful as subclassing, yet it implies reuse by design as one clearly needs to think about allowing composition - more about that for example in ClarityOfTypes.

TBD: clear definition of version TBD: Separation of ClientAPI and ProviderAPI