Single Responsibility Principle

SRP

Kind: principle

Layer: Structural Core

Aliases: SRP, Single Responsibility Principle

Record: architecture:single-responsibility

Severity: mandatory

Scope: class, module, service

Canonical: Ontology

A design rule that a class or module has one reason to change, because it serves one responsibility.

Listed in Architecture principles, after Immutable Infrastructure and before Separation of Concerns.

Requires

• High Cohesion
• Explicit Boundaries

Reinforces

• Separation of Concerns
• Modularity
• Testability

Enables

• Replaceability
• Reusability

Conflicts with

• God Object
• Divergent Change

In tension with

• Excessive Fragmentation

Tensions

• Single Responsibility Principle (SRP) / Excessive Fragmentation

Violated by

• God Object
• Divergent Change

Refactored by

• Extract Class
• Extract Module
• Split Bounded Context
• Move Behavior to Its Owner

Severity

• mandatory

Category

• Core Modular Design

Enforced by

• rules/eslint/file-length.eslint.rule.ts

Reinforced by

• Domain Service
• Interface Segregation Principle
• Command Pattern
• Chain of Responsibility Pattern
• Iterator Pattern
• Pipes and Filters

Linked from

• The structural domain
• Anti-patterns
• Domain Architecture
• Correctness / Determinism / Verification
• Core Modular Design
• SOLID / Object-Oriented Design
• Behavioral Patterns
• Codebase / System Architecture Styles
• Core Modular Design
• Domain Architecture
• Severity levels
• The resolutions