clean-code-detect-smells

Clean Code: Detect Code Smells

Systematically identify code smells — surface indicators of deeper design problems — and prioritize them for refactoring.

When This Skill Applies

• Reviewing code for quality issues
• The codebase feels "hard to work with" but the problems are not obvious
• The user mentions code smells, technical debt, or code quality
• Preparing a refactoring plan
• During code review to provide structured feedback

Core Principle

A code smell is a surface indication that usually corresponds to a deeper problem in the system. Smells are not bugs — the code works. But they signal that the design is becoming harder to understand, modify, or extend. Detecting smells early prevents them from compounding into costly structural problems.

Workflow

Step 1: Scan for Bloater Smells

Look for entities that have grown too large: long methods, large classes, long parameter lists, data clumps, primitive obsession.

Step 2: Scan for Coupler Smells

Look for excessive coupling: feature envy, inappropriate intimacy, message chains, middle man.

Step 3: Scan for Change-Prevention Smells

Look for patterns that make changes risky: divergent change (one class changed for many reasons), shotgun surgery (one change touches many classes), parallel inheritance hierarchies.

Step 4: Scan for Dispensable Smells

Look for things that should not exist: dead code, speculative generality, lazy class, duplicate code, unnecessary comments.

Step 5: Prioritize by Impact

Rate each smell by: frequency (how often it occurs), impact (how much it slows development), and effort (how hard it is to fix). Fix high-frequency, high-impact, low-effort smells first.

Detection / Indicators

Bloaters

Smell	Detection Rule
Long Method	More than 15 lines of logic
Large Class	More than 200 lines or 7+ public methods
Long Parameter List	More than 3 parameters
Data Clumps	Same group of fields appears together in multiple places
Primitive Obsession	Using strings, numbers, or booleans instead of value objects