behavioural

Behavioural design patterns are used to decouple object interactions and manage varying behavior across contexts. They provide structured templates to coordinate responsibilities, enabling systems to react to events without tight coupling.

Choosing the right behavioural pattern for a stateful component involves evaluating interaction needs: State manages internal state transitions, Strategy swaps algorithms, and Observer handles event-driven updates. Rationale and trade-offs help guide the selection.

To decouple middleware chains without tight object dependencies, apply the Chain of Responsibility pattern. It structures processing pipelines into small, replaceable components that pass requests sequentially, making the interaction chains easier to extend and test.

Use the Command pattern over the Strategy pattern when you need to encapsulate requests as objects for undo/redo capabilities or queuing. Use Strategy when you need to swap algorithms dynamically within a single context without altering the structure.

Yes, this covers all 10 GoF behavioural patterns including Mediator, Visitor, Chain of Responsibility, Command, Strategy, State, Observer, Memento, Iterator, and Template Method. It provides code templates and rationale for each.

Limitations of behavioural design patterns include potential over-engineering for simple interactions and added complexity from indirection layers. Maintenance trade-offs and side effects must be evaluated to ensure the decoupling benefits justify the structural overhead.