Analysis
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Evaluate design patterns side by side across intent, tradeoffs, languages, and integration fit.
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Analysis
Pattern comparison
Reviewing 3 patterns.
| Criteria | |||
|---|---|---|---|
| Basics | |||
| Category | behavioral | creational | creational |
| Summary | — | — | — |
| Intent | Define a subscription mechanism so multiple observers can react to subject events without the subject knowing concrete subscriber details. | Specify the kinds of objects to create using a prototypical instance, and create new objects by cloning that prototype. | Ensure a class has only one instance and provide a global access point to it. |
| Decision factors | |||
| Problem | A system needs to notify multiple dependent objects when state changes occur, but hardcoding those dependencies makes the design rigid and tightly coupled. | Creating new objects from scratch can be expensive or repetitive when the system needs many similar variants. | A system needs exactly one shared instance of a class, and that instance must be globally accessible without allowing uncontrolled duplication. |
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| Integration notes | Observers work well inside a single application boundary for UI events, domain events, and in-process notifications where subscribers change dynamically. | Prototype is useful when object creation is expensive, when many near-identical objects are needed, or when cloning preconfigured templates is simpler than rebuilding them. | Singleton is useful for centralized services like configuration, logging, caching, and shared application state. |