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- Design patterns are reusable solutions to common software design problems, not algorithms but structures for data flow.
- The Observer Pattern allows an observable object to notify multiple observer objects when an event occurs.
- Common uses include asynchronous events (e.g., network data receipt) and GUI event handling (e.g., button clicks).
- Observers register callbacks; the observable notifies all registered observers when the event happens.
- Benefits: decoupling, easy addition of new observers without modifying existing code, and support for multiple listeners.
- Example: a GoatDetector class that notifies observers when the word 'goat' appears in input.
- A more advanced version uses a dictionary to map events to lists of observers, supporting multiple event types.
- The Observer Pattern is a concept, not a rigid implementation; it can be adapted to fit various scenarios.