# Decorator Pattern

> A design pattern that adds behavior to an object by wrapping it in another object with the same interface.

Record: `architecture:decorator-pattern`
Kind: pattern
Layer: [Design Patterns Core](https://banes-lab.com/records/layer/design-patterns-core.md)
Severity: contextual
Scope: behavior composition
Canonical: https://banes-lab.com/ontology#architecture-decorator-pattern

Listed in [Architecture principles](https://banes-lab.com/api/records/architecture.md), after [Bridge Pattern](https://banes-lab.com/records/architecture/bridge-pattern.md) and before [Composite Pattern](https://banes-lab.com/records/architecture/composite-pattern.md).

## Repair

- Refactored by: Introduce Decorator
- Detected by: repeated wrapper-like subclasses
- Violated by: many subclasses for optional features
- Measured by: variant explosion count
- Enforced by: interface conformance tests

## Requires

- [Common Interface](https://banes-lab.com/records/lexicon/common-interface.md)

## Reinforces

- [Open/Closed Principle (OCP)](https://banes-lab.com/records/architecture/open-closed.md)
- [Composability](https://banes-lab.com/records/architecture/composability.md)

## Enables

- [Runtime Behavior Extension](https://banes-lab.com/records/lexicon/runtime-behavior-extension.md)

## Conflicts with

- [Subclass Explosion](https://banes-lab.com/records/lexicon/subclass-explosion.md)

## In tension with

- [Stack Debugging](https://banes-lab.com/records/lexicon/stack-debugging.md)

## Tensions

- [Decorator Pattern / Stack Debugging](https://banes-lab.com/records/tension/decorator-pattern-stack-debugging.md)

## Severity

- [contextual](https://banes-lab.com/records/vocabulary/severity-contextual.md)

## Category

- [Structural Patterns](https://banes-lab.com/records/architecture-category/structural-patterns.md)

## Enabled by

- [Composition Over Inheritance](https://banes-lab.com/records/architecture/composition-over-inheritance.md)

## Linked from

- [Core Modular Design](https://banes-lab.com/ontology/principles/architecture-category-core-modular-design.md)
- [SOLID / Object-Oriented Design](https://banes-lab.com/ontology/principles/architecture-category-solid-object-oriented-design.md)
- [Behavioral Patterns](https://banes-lab.com/ontology/principles/architecture-category-behavioral-patterns.md)
- [Structural Patterns](https://banes-lab.com/ontology/lexicon/lexicon-category-structural-patterns.md)
- [Severity levels](https://banes-lab.com/ontology/schema/the-vocabulary-severity.md)
- [The resolutions](https://banes-lab.com/ontology/schema/the-resolutions.md)