Encapsulation

Kind: principle

Layer: Structural Core

Record: architecture:encapsulation

Severity: mandatory

Scope: class, module, component

Canonical: Ontology

A design rule that an object's state is changed only through its own operations, which keep its invariants.

Listed in Architecture principles, after Low Coupling and before Information Hiding.

Requires

• Information Hiding
• Stable Interfaces

Reinforces

• Abstraction
• Low Coupling

Enables

• Change Isolation
• Invariant Protection

Conflicts with

• Exposed Internals
• Exposed Internals
• Feature Envy

In tension with

• Debuggability
• Introspection
• Introspection / Encapsulation

Tensions

• Encapsulation / Debuggability

Violated by

• Exposed Internals
• Shared Mutable State

Refactored by

• Encapsulate State
• Extract Function
• Restrict Exports

Severity

• mandatory

Category

• Core Modular Design

Reinforced by

• Explicit Boundaries
• Aggregate
• Value Object
• Entity
• High Cohesion
• Iterator Pattern
• Factory Pattern
• Facade Pattern
• Proxy Pattern

Required by

• Invariant
• Command Pattern
• Memento Pattern
• State Isolation

Linked from

• The direction axis
• The structural domain
• Separate, trade, or mitigate
• Anti-patterns
• Domain Architecture
• Contracts / Interfaces / Compatibility
• Core Modular Design
• Metaprogramming / Language-Oriented Architecture
• Behavioral Patterns
• Creational Patterns
• Structural Patterns
• Transactions / State / Concurrency
• Core Modular Design
• Quality Attributes
• Severity levels
• The resolutions