# Flyweight Pattern

> A design pattern that shares one copy of immutable intrinsic state among many objects, each keeping only its own extrinsic state.

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

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

## Repair

- Refactored by: Extract Flyweight, Share Intrinsic State
- Detected by: repeated equal intrinsic state across objects
- Violated by: identical heavy state duplicated across many instances
- Measured by: duplicate-state memory footprint
- Enforced by: profiling review

## Requires

- [Separable Intrinsic State](https://banes-lab.com/records/lexicon/separable-intrinsic-state.md)

## Reinforces

- [Memory Efficiency](https://banes-lab.com/records/architecture/memory-efficiency.md)

## Enables

- [Shared Immutable State](https://banes-lab.com/records/lexicon/shared-immutable-state.md)
- [High-Cardinality Object Reuse](https://banes-lab.com/records/lexicon/high-cardinality-object-reuse.md)

## Conflicts with

- [Per-Instance Duplicate State](https://banes-lab.com/records/lexicon/per-instance-duplicate-state.md)

## In tension with

- [Complexity](https://banes-lab.com/records/lexicon/complexity.md)

## Tensions

- [Flyweight Pattern / Complexity](https://banes-lab.com/records/tension/complexity-flyweight-pattern.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)

## Linked from

- [Scalability / Performance / Optimization](https://banes-lab.com/ontology/principles/architecture-category-scalability-performance-optimization.md)
- [Quality Attributes](https://banes-lab.com/ontology/lexicon/lexicon-category-quality-attributes.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)