Wrapper

A wrapper is any component that sits in front of another component or building block to abstract away its concrete interface or implementation, without changing what that component actually does. Callers depend on the wrapper instead of on the thing it wraps.

"Wrapper" is an umbrella term rather than a single design pattern, and several more specific patterns fall under it.

• The decorator pattern, which attaches additional responsibilities to an object dynamically.
• The adapter pattern, which reconciles two mismatched interfaces.
• The facade, which simplifies a complex subsystem behind a narrower interface.
• The gateway, which encapsulates access to an external system.

Different sources draw the boundaries between these terms slightly differently, and in practice the small differences rarely matter.

What does matter is that wrapping a component has clear, consistent semantics within a single system. Whichever of these patterns a team adopts for a given case, the important thing is that "wrapping" means the same thing everywhere it’s used, so that a reader can tell at a glance what a wrapper is and isn’t allowed to do.