# Command Pattern

> A design pattern that wraps a request in an object, so it can be queued, deferred or undone.

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

Listed in [Architecture principles](https://banes-lab.com/api/records/architecture.md), after [Mediator Pattern](https://banes-lab.com/records/architecture/mediator-pattern.md) and before [State Pattern](https://banes-lab.com/records/architecture/state-pattern.md).

## Repair

- Refactored by: Encapsulate Invocation as a Command object
- Detected by: switch/if chains selecting an operation to run
- Violated by: inline conditional dispatch on an action name
- Measured by: dispatch-branch count per action site
- Enforced by: [design review](https://banes-lab.com/records/architecture/design-review.md)

## Requires

- [Encapsulation](https://banes-lab.com/records/architecture/encapsulation.md)

## Reinforces

- [Open/Closed Principle (OCP)](https://banes-lab.com/records/architecture/open-closed.md)
- [Single Responsibility Principle (SRP)](https://banes-lab.com/records/architecture/single-responsibility.md)

## Enables

- [Undo/Redo](https://banes-lab.com/records/lexicon/undo-redo.md)
- [Deferred Execution](https://banes-lab.com/records/lexicon/deferred-execution.md)
- [Deferred Execution](https://banes-lab.com/records/lexicon/deferred-execution.md)

## Conflicts with

- [Direct Method Invocation](https://banes-lab.com/records/lexicon/direct-method-invocation.md)

## In tension with

- [Simplicity](https://banes-lab.com/records/lexicon/simplicity.md)

## Tensions

- [Command Pattern / Simplicity](https://banes-lab.com/records/tension/command-pattern-simplicity.md)

## Severity

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

## Category

- [Behavioral Patterns](https://banes-lab.com/records/architecture-category/behavioral-patterns.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/lexicon/lexicon-category-behavioral-patterns.md)
- [Core Vocabulary](https://banes-lab.com/ontology/lexicon/lexicon-category-core-vocabulary.md)
- [Quality Attributes](https://banes-lab.com/ontology/lexicon/lexicon-category-quality-attributes.md)
- [Severity levels](https://banes-lab.com/ontology/schema/the-vocabulary-severity.md)
- [The resolutions](https://banes-lab.com/ontology/schema/the-resolutions.md)