When to Use Adapter Pattern vs Alternatives
The Adapter Pattern is not always the right choice. Understanding when to use it versus alternatives, and when it becomes overkill, is crucial for clean design decisions.
Use Adapter Pattern When
1. Interface Incompatibility Exists: You have an existing class with useful functionality but its interface does not match what your client expects. Modifying the existing class is not possible (third-party library) or not desirable (violates Open-Closed Principle).
2. Reusing Legacy Code: You need to integrate legacy systems into new architectures without rewriting them. The legacy system works correctly but has outdated interfaces.
3. Multiple Incompatible Implementations: You need to support multiple third-party services (like different payment gateways, notification services, or storage providers) with different APIs through a uniform interface.
Avoid Adapter Pattern When
1. You Control Both Interfaces: If you own both the client and the service code, refactor to use a common interface directly rather than adding adapter layers. The adapter adds unnecessary indirection.
2. Simple Wrapping Suffices: If you only need to add behavior without interface translation, use the Decorator Pattern instead. Adapter focuses on interface conversion, not behavior enhancement.
3. Complex Translation Logic: If the translation between interfaces requires substantial business logic or complex transformations, the adapter becomes a God Object. Consider using a Facade or a dedicated service layer instead.
Adapter vs Similar Patterns
When Adapter Becomes Overkill
Scenario 1: Trivial Conversion
If the adaptation only renames a method with identical signatures, a simple wrapper function may suffice. Creating full adapter classes adds unnecessary ceremony for one-line delegations.
Scenario 2: Single Use Case
If you only have one incompatible class and one client, directly calling the incompatible class may be acceptable. Document the interface mismatch but avoid premature abstraction. However, if future incompatible classes are likely, use the adapter from the start.
Scenario 3: Performance-Critical Path
In high-frequency, low-latency systems (like HFT - High-Frequency Trading), the indirection layer of adapters may introduce unacceptable overhead. Profile first, but if confirmed, consider direct integration with performance-critical components.