Analysis
Compare patterns
Evaluate design patterns side by side across intent, tradeoffs, languages, and integration fit.
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Analysis
Pattern comparison
Reviewing 3 patterns.
| Criteria | |||
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| Basics | |||
| Category | structural | behavioral | behavioral |
| Summary | Compose objects into tree structures to represent part-whole hierarchies and let clients work with individual and composite objects through the same interface. | — | — |
| Intent | Compose objects into tree structures to represent part-whole hierarchies and let clients work with individual and composite objects through the same interface. | Define a subscription mechanism so multiple observers can react to subject events without the subject knowing concrete subscriber details. | Define the skeleton of an algorithm in a base class and let subclasses override selected steps without changing the overall structure. |
| Decision factors | |||
| Problem | A system needs to treat individual objects and groups of objects uniformly, but the hierarchy becomes difficult to manage with separate code paths. | A system needs to notify multiple dependent objects when state changes occur, but hardcoding those dependencies makes the design rigid and tightly coupled. | Several classes share the same algorithm structure, but some steps need to vary between implementations. |
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| Integration notes | Composite is useful when a hierarchy of nested objects should expose a common interface, such as files and folders, menus and submenus, org charts, widget trees, or scene graphs. | Observers work well inside a single application boundary for UI events, domain events, and in-process notifications where subscribers change dynamically. | Template Method is useful when you have repeated workflows with a common sequence of steps, such as processing orders, generating reports, and importing data. |