This is the \b[<decorator pattern>, a <structural pattern>]. `BasicPlan` supplies the initial component. `Packages` stores another `CableTV` behind the same interface and delegates to it; `Movies` and `HDChannels` add their own price and description. Wrapping one package around another combines the optional responsibilities without constructing a subclass for each possible combination.

Solution

Past exam of the year 1 of the computer science course of the University of Oxford / 2017 / Imperative programming / 5 / b / Solution

 Solution (source code)