Clean Code

1---
2name: clean-code
3description: "Applies principles from Robert C. Martin's 'Clean Code'. Use this skill when writing, reviewing, or refactoring code to ensure high quality, readability, and maintainability. Covers naming, functions, comments, error handling, and class design."
4user-invocable: true
5risk: safe
6source: "ClawForge (https://github.com/jackjin1997/ClawForge)"
7---
8 
9# Clean Code Skill
10 
11This skill embodies the principles of "Clean Code" by Robert C. Martin (Uncle Bob). Use it to transform "code that works" into "code that is clean."
12 
13## 🧠 Core Philosophy
14> "Code is clean if it can be read, and enhanced by a developer other than its original author." — Grady Booch
15 
16## When to Use
17Use this skill when:
18- **Writing new code**: To ensure high quality from the start.
19- **Reviewing Pull Requests**: To provide constructive, principle-based feedback.
20- **Refactoring legacy code**: To identify and remove code smells.
21- **Improving team standards**: To align on industry-standard best practices.
22 
23## 1. Meaningful Names
24- **Use Intention-Revealing Names**: `elapsedTimeInDays` instead of `d`.
25- **Avoid Disinformation**: Don't use `accountList` if it's actually a `Map`.
26- **Make Meaningful Distinctions**: Avoid `ProductData` vs `ProductInfo`.
27- **Use Pronounceable/Searchable Names**: Avoid `genymdhms`.
28- **Class Names**: Use nouns (`Customer`, `WikiPage`). Avoid `Manager`, `Data`.
29- **Method Names**: Use verbs (`postPayment`, `deletePage`).
30 
31## 2. Functions
32- **Small!**: Functions should be shorter than you think.
33- **Do One Thing**: A function should do only one thing, and do it well.
34- **One Level of Abstraction**: Don't mix high-level business logic with low-level details (like regex).
35- **Descriptive Names**: `isPasswordValid` is better than `check`.
36- **Arguments**: 0 is ideal, 1-2 is okay, 3+ requires a very strong justification.
37- **No Side Effects**: Functions shouldn't secretly change global state.
38 
39## 3. Comments
40- **Don't Comment Bad Code—Rewrite It**: Most comments are a sign of failure to express ourselves in code.
41- **Explain Yourself in Code**: 
42  ```python
43  # Check if employee is eligible for full benefits
44  if employee.flags & HOURLY and employee.age > 65:
45  ```
46  vs
47  ```python
48  if employee.isEligibleForFullBenefits():
49  ```
50- **Good Comments**: Legal, Informative (regex intent), Clarification (external libraries), TODOs.
51- **Bad Comments**: Mumbling, Redundant, Misleading, Mandated, Noise, Position Markers.
52 
53## 4. Formatting
54- **The Newspaper Metaphor**: High-level concepts at the top, details at the bottom.
55- **Vertical Density**: Related lines should be close to each other.
56- **Distance**: Variables should be declared near their usage.
57- **Indentation**: Essential for structural readability.
58 
59## 5. Objects and Data Structures
60- **Data Abstraction**: Hide the implementation behind interfaces.
61- **The Law of Demeter**: A module should not know about the innards of the objects it manipulates. Avoid `a.getB().getC().doSomething()`.
62- **Data Transfer Objects (DTO)**: Classes with public variables and no functions.
63 
64## 6. Error Handling
65- **Use Exceptions instead of Return Codes**: Keeps logic clean.
66- **Write Try-Catch-Finally First**: Defines the scope of the operation.
67- **Don't Return Null**: It forces the caller to check for null every time.
68- **Don't Pass Null**: Leads to `NullPointerException`.
69 
70## 7. Unit Tests
71- **The Three Laws of TDD**:
72  1. Don't write production code until you have a failing unit test.
73  2. Don't write more of a unit test than is sufficient to fail.
74  3. Don't write more production code than is sufficient to pass the failing test.
75- **F.I.R.S.T. Principles**: Fast, Independent, Repeatable, Self-Validating, Timely.
76 
77## 8. Classes
78- **Small!**: Classes should have a single responsibility (SRP).
79- **The Stepdown Rule**: We want the code to read like a top-down narrative.
80 
81## 9. Smells and Heuristics
82- **Rigidity**: Hard to change.
83- **Fragility**: Breaks in many places.
84- **Immobility**: Hard to reuse.
85- **Viscosity**: Hard to do the right thing.
86- **Needless Complexity/Repetition**.
87 
88## 🛠️ Implementation Checklist
89- [ ] Is this function smaller than 20 lines?
90- [ ] Does this function do exactly one thing?
91- [ ] Are all names searchable and intention-revealing?
92- [ ] Have I avoided comments by making the code clearer?
93- [ ] Am I passing too many arguments?
94- [ ] Is there a failing test for this change?
95