Delegation
Delegation is a composition pattern in which one object forwards operations or property lookup to another object that provides the behavior.
The Joy of JavaScript
A composition style in which an object forwards behavior or property lookup to another object through delegation links rather than copying or class inheritance.
- How it is used
- Uses delegation to reuse behavior across linked JavaScript domain objects without requiring a class-inheritance design.
- How deep it goes
- Works through Object.create links, prototype lookup, and initialization; contrasts explicit references without developing that technique further.
- Examples
- Shows a linked blockchain store and transaction objects, plus implicit and explicit formatter calls.
- What you can do after
- Build it from scratch with Object.create links and initialization methods, then distinguish prototype delegation from explicit references and mixin composition.
Kotlin in Action, 2E
- How it is used
- Reduces wrapper and accessor boilerplate when behavior should be forwarded to a contained object or helper.
- How deep it goes
- Explains compiler-generated class forwarding and property delegates through observable-property refactoring, including getValue and setValue conventions.
- Examples
- Uses a CountingSet wrapper and observable Person age and salary properties to demonstrate selective forwarding.
- What you can do after
- Apply it via Kotlin’s by syntax and Delegates.observable to customize selected behavior without rewriting routine forwarding code.
Related concepts
- method_missingused by · method_missing is a Ruby method invoked as a last resort when an object receives a message for which no matching method is found.
- delegated propertyimplements · A delegated property is a Kotlin property whose read and write behavior is provided by a separate delegate object.
- classcontrasts with · A class is a programming-language construct that defines a type’s structure or behavior and provides a basis for creating or representing objects.
- Kotlinimplemented by · Kotlin is a statically typed general-purpose programming language that targets the JVM and other platforms and interoperates with Java.
- backward compatibilityimplements · Backward compatibility is the property of a changed or newer system remaining usable by existing clients and consumers of its earlier interfaces, behavior, or data.
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