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 | |||
|---|---|---|---|
| Basics | |||
| Category | structural | behavioral | creational |
| Summary | Provide a simplified high-level interface that coordinates a complex subsystem behind a smaller and easier-to-use API. | — | — |
| Intent | Provide a simplified high-level interface that coordinates a complex subsystem behind a smaller and easier-to-use API. | Define a subscription mechanism so multiple observers can react to subject events without the subject knowing concrete subscriber details. | Ensure a class has only one instance and provide a global access point to it. |
| Decision factors | |||
| Problem | A client needs to perform a recurring workflow that spans several subsystem classes, but direct coordination makes the code noisy and tightly coupled. | A system needs to notify multiple dependent objects when state changes occur, but hardcoding those dependencies makes the design rigid and tightly coupled. | 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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| Practical fit | |||
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| Integration notes | Facades are useful when exposing a stable boundary over a multi-service or mixed-language backend, or when presenting a consistent UI entry point over multiple readiness checks. | Observers work well inside a single application boundary for UI events, domain events, and in-process notifications where subscribers change dynamically. | Singleton is useful for centralized services like configuration, logging, caching, and shared application state. |