Pattern Design Ultimate Design Pattern 3

Question 1

The Bridge pattern separates an abstraction from its implementation so that the two can vary independently. What is the core structural mechanism?

Accepted Answer

Composition — the abstraction holds a reference to the implementation

Answer

Bridge uses composition: the abstraction contains a reference to an implementor object, decoupling the two hierarchies.

Question 2

In a creational context, which pattern creates objects by copying an existing prototype instead of constructing from scratch?

Accepted Answer

Prototype

Answer

The Prototype pattern clones an existing object, which is useful when instantiation is expensive or complex.

Question 3

Which behavioral pattern defines a one-to-many dependency so that when one object changes state, all its dependents are notified automatically?

Accepted Answer

Observer

Answer

The Observer pattern (also called Publish-Subscribe) automatically propagates changes from a subject to all registered observers.

Question 4

What problem does the Flyweight pattern solve?

Accepted Answer

Supporting a large number of fine-grained objects efficiently by sharing state

Answer

Flyweight reduces memory usage by sharing intrinsic (immutable) state across many similar objects, storing extrinsic state outside.

Question 5

The Chain of Responsibility pattern passes a request along a chain of handlers. What happens when no handler in the chain processes the request?

Accepted Answer

The request reaches the end of the chain unhandled — behavior depends on implementation

Answer

By default, an unhandled request reaches the end of the chain; whether to throw, log, or silently drop it is an implementation decision.

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