Hints that the code you're reading is a messRigidity No change is trivial, every change in the code add more twists and tangles. | Complexity As above, no change is trivial and requires a lot of research. | Fragility Changes breaking other parts of the code. | Immobility You cannot reuse part of the existing code |
General RulesFollow the Boy Scout Rule : Leave the code cleaner than when you found it | | Follow Standard Conventions, both langage related and team related | Keep it simple stupid | Don't repeat yourself | Be consistent | Do not override safeties |
Design RulesFunctions should descend only one level of abstraction, and statements in a function should be at the same level of abstraction | Use dependency injection | Keep your boundaries clean | Encapsulate conditionals, try to avoid negative conditionals | Make logical dependencies physical | Use polymorphism instead of if / else or switch / case | Avoid hidden temporal couplings | Keep configurable data (ie: constants) at high levels, they should be easy to change | Use Enums over constants |
Source Code StructureUse vertical formatting to separate your code and different concepts, you should read your code from top to bottom without "jumping" over functions | Variables should be declared as close to their usage as possible | Instance variables should be declared at the top of the class | Put statics methods on top of the package | Similar and dependent functions should be close vertically | Balance between vertical openness and vertical density. Same rules apply for horizontal density | Do not align your code horizontally | Use consistent indentation |
| | Naming RulesUse descriptive and intention-revealing variable names | Make meaningful distinctions | Use pronounceable and searchable names | Avoid disinformation and encoded names | Avoid member prefixes or types information (Hungarian Notation) | Avoid mental mapping | Replace Magic Numbers with Constants |
FunctionsFunctions should do one thing and they should do it well | Functions should be relatively small | Functions should have descriptives names | Functions should have as few arguments as possible (no more than 3 if possible) | Functions should have no side effects | Use explanatory variables to explain your intent / algorithm | Don't use flag arguments | Avoid output arguments, they're misleading |
Objects VS Data StructuresData structures exposes data and have no behavior.
So, procedural code makes it easy to add new function without changing the existing data structures. | Objects expose behavior and hide data.
Object Oriented code makes it easy to add new classes without changing existing functions | Avoid hybrids (half object and half data structure) | | | The Law of Demeter : A class should not know about the innards of the objects it manipulates. Objects should not expose theirs internals. | Same as functions : they should do one thing and they should be small | Avoid and split Train Wrecks : objectA.getB().getC().getD(); | Keep the number of instance variables low, if your class have too many instance variable, then it is probably doing more than one thing |
Error handlingError handling is one thing, don't mix error handling and code | Use Exceptions instead of returning error codes | Write the try-catch-finally statement first, it will help you structure your code | Don't return null, don't pass null either | Throw exceptions with context |
| | TestsF.I.R.S.T : Fast, Independent, Repeatable, Self-Validating, Timely | One assert per test | Keep your tests as clean as your production code, they should be easily readable | Use a coverage tool | Tests should be easy to run |
TDD3 Laws of Test Driven Development, this should ensure that you write your tests and your code simultaneously | You may not write production code until you have written a failing unit test | You may not write more of a unit test than is sufficient to fail, and not compiling count as failing | You may not write production code that is sufficient to pass the currently failing test |
CommentsWhen to write a comment ? Explain yourself in code, not in comment. If it's not possible, take your time to write a GOOD comment. | What makes up a Good comment ? Use comments to inform, explain, clarify, or warn the reader | Comment-out code ? DELETE IT | |
| Avoid using more than one langage in a single source file (Html comments, Javadoc for nonplublic code) | Avoid inappropriate Informations (change history, license, ...) | Avoid misleading or noise comments | Don't be redundant ( i++; // increment i) | Closing brace comments (} // end of function) |
CreditsFrom "Clean Code" by Robert C. Martin | | | | By Coste Maxime |
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Thanks for putting this together—very useful reference!
I did notice one typo: the first item under 'General Rules' should be the "Boy Scout Rule".
Thanks for your comment !
It's fixed now.
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