Do Not Repeat Yourself

DRY

Kind: principle

Layer: Structural Core

Aliases: DRY, Do Not Repeat Yourself, Don't Repeat Yourself

Record: architecture:duplicate-code

Severity: mandatory

Scope: function, module, domain

Canonical: Ontology

A design rule that each piece of logic, constant or schema has one source in the code, and every other use refers to it.

Listed in Architecture principles, after Separation of Concerns and before High Cohesion.

Requires

• Abstraction
• Canonical Source

Reinforces

• Single Source of Truth
• Reusability

Enables

• Consistency
• Maintainability

Conflicts with

• Copy-Paste Programming

In tension with

• Locality of Behavior
• Simplicity

Tensions

• Do Not Repeat Yourself (DRY) / Locality of Behavior
• Do Not Repeat Yourself (DRY) / Simplicity

Violated by

• Copy-Paste Programming

Refactored by

• Extract Function
• Extract Module
• Introduce Parameter Object
• Centralize the Rule

Severity

• mandatory

Category

• Core Modular Design

Enforced by

• rules/eslint/closure-no-platform-capability-redefine.eslint.rule.ts

Detected by

• rules/eslint/markup-through-builder.eslint.rule.ts

Reinforced by

• Metaprogramming
• Normalization

Linked from

• One home
• Counting copies
• The structural domain
• Separate, trade, or mitigate
• The principle architecture
• Core Modular Design
• Metaprogramming / Language-Oriented Architecture
• Schema / Canonical Data / Semantics
• Transactions / State / Concurrency
• Core Modular Design
• Quality Attributes
• Severity levels
• The resolutions