Summary

Pattern Comparison

Pattern	When to Apply	Strengths	Caveats	Common Use Cases
Adapter	When the existing interface is incompatible	Provides a unified API to the caller	Adapter can grow complex with heavy logic	External APIs, legacy libraries, compatibility
Facade	When internal processes are too complex	Simplifies APIs and combines multiple calls	Structure differs from the real logic	UI-facing APIs, subsystem integration
Proxy	When inserting access control or caching logic	Flexible interception (e.g. lazy, logging)	Doesn’t transform behavior	Caching, authentication, request tracing

Choosing the Right Pattern

• Connecting to a legacy or incompatible interface? → Use Adapter
• Simplifying complex API calls? → Use Facade
• Want to insert extra behavior (auth, cache)? → Use Proxy

Team Discussion Snippets

• “This old API is unavoidable—let’s wrap it with an Adapter.”
• “We should abstract it behind a unified interface so we can switch implementations later.”
• “Calling .printText() directly everywhere feels risky—let’s add a transformation layer.”