# Polymorphism

> A mechanism that lets one interface have several implementations, with the implementation chosen by the object that receives the call.

Record: `architecture:polymorphism`
Kind: mechanism
Layer: [Structural Core](https://banes-lab.com/records/layer/structural-core.md)
Severity: recommended
Scope: class, interface, runtime
Canonical: https://banes-lab.com/ontology#architecture-polymorphism

Listed in [Architecture principles](https://banes-lab.com/api/records/architecture.md), after [Liskov Substitution Principle (LSP)](https://banes-lab.com/records/architecture/liskov-substitution.md) and before [Event-Driven Architecture](https://banes-lab.com/records/architecture/event-driven-architecture.md).

## Repair

- Refactored by: [Replace Conditional with Polymorphism](https://banes-lab.com/records/lexicon/replace-conditional-with-polymorphism.md)
- Detected by: conditional type checks, duplicated branching
- Violated by: instanceof/switch dispatch over types
- Measured by: polymorphic dispatch ratio
- Enforced by: [code review](https://banes-lab.com/records/architecture/code-review.md), static analysis rules

## Requires

- [Abstraction](https://banes-lab.com/records/architecture/abstraction.md)
- [Substitutability](https://banes-lab.com/records/lexicon/substitutability.md)

## Reinforces

- [Open/Closed Principle (OCP)](https://banes-lab.com/records/architecture/open-closed.md)
- [Strategy Pattern](https://banes-lab.com/records/architecture/strategy-pattern.md)

## Enables

- [Dynamic Dispatch](https://banes-lab.com/records/architecture/dynamic-dispatch.md)
- [Interchangeability](https://banes-lab.com/records/architecture/interchangeability.md)

## Conflicts with

- [Type Switching](https://banes-lab.com/records/lexicon/type-switching.md)

## In tension with

- [Traceability](https://banes-lab.com/records/architecture/traceability.md)

## Tensions

- [Polymorphism / Traceability](https://banes-lab.com/records/tension/polymorphism-traceability.md)

## Severity

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

## Category

- [SOLID / Object-Oriented Design](https://banes-lab.com/records/architecture-category/solid-object-oriented-design.md)

## Reinforced by

- [Dynamic Binding](https://banes-lab.com/records/architecture/dynamic-binding.md)
- [Liskov Substitution Principle](https://banes-lab.com/records/architecture/liskov-substitution.md)
- [State Pattern](https://banes-lab.com/records/architecture/state-pattern.md)
- [Null Object Pattern](https://banes-lab.com/records/architecture/null-object-pattern.md)

## Linked from

- [Runtime Discovery / Dynamic Binding](https://banes-lab.com/ontology/principles/architecture-category-runtime-discovery-dynamic-binding.md)
- [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)
- [Observability / Auditability / Traceability](https://banes-lab.com/ontology/principles/architecture-category-observability-auditability-traceability.md)
- [Behavioral Patterns](https://banes-lab.com/ontology/principles/architecture-category-behavioral-patterns.md)
- [Quality Attributes](https://banes-lab.com/ontology/lexicon/lexicon-category-quality-attributes.md)
- [SOLID / Object-Oriented Design](https://banes-lab.com/ontology/lexicon/lexicon-category-solid-object-oriented-design.md)
- [Severity levels](https://banes-lab.com/ontology/schema/the-vocabulary-severity.md)
- [The resolutions](https://banes-lab.com/ontology/schema/the-resolutions.md)