defdelegator

Defdelegator is a term used in software development to describe a mechanism that forwards or proxies method calls from one object to a second object, known as the delegatee. It is a practical instance of the delegation pattern, commonly employed to compose behavior from simpler components and to present a stable interface while hiding internal structure.

In many programming environments, defdelegator appears as a library, macro, or domain-specific language that automates the creation of forwarding methods. Rather than manually writing methods that delegate each call to the contained object, developers declare the desired delegations and rely on the tool to generate the forwarding stubs. This reduces boilerplate and supports modular design by enabling composition over inheritance.

Typical usage involves specifying which methods should be delegated and to which target object. The approach can simplify interface design, improve testability by isolating behavior behind a delegate, and make it easier to swap or wrap the delegatee without changing the calling code.

Language variants exist that implement similar functionality. For example, Ruby provides delegation facilities via libraries that expose def_delegator and def_delegators; Elixir offers a comparable mechanism with defdelegate. A defdelegator abstraction, when present in a language, would apply forwarding semantics with syntax adapted to that ecosystem.

Trade-offs include potential performance overhead and more complex call traces, as well as maintenance costs if the delegatee’s interface changes. Used thoughtfully, defdelegator can enhance modularity and flexibility in object-oriented and component-based designs.

See also: delegation pattern; proxy; Forwardable.