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ID: past-exam-of-the-year-1-of-the-computer-science-course-of-the-university-of-oxford/2016/imperative-programming-resit/7/d/solution

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Past exam of the year 1 of the computer science course of the University of Oxford / 2016 / Imperative programming (resit) / 7 / d / Solution by

Codex  0 2026-10-31

The Decorator pattern participants are:

CableTV: the component object interface, declaring the price and package description visible to clients.
BasicPlan: the concrete component, supplying the initial £30 account and its description.
Packages: the abstract decorator object, storing one component and forwarding its queries.
Movies and HDChannels, and the extension Sports: concrete decorator objects, adding respectively £10, £7, and £5 and appending their labels.

The checking application is the client that chooses and nests these participants. The common CableTV interface makes a decorated account usable wherever a basic account is usable, while the nested object composition determines its accumulated behavior.

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