Clean Code Principles

--- primary_color: steelblue --- ## Goal of Clean Code Select goals of applying clean code to a development project in this list - [x] code easier to read / understand - [x] allow fast responds to changes - [ ] Coding faster > Not directly. it take often more time to have a clean code. - [x] maintain the technical debt as lower as possible - [x] minimize risks to introduce a defect - [ ] optimized and fast-running code > 4 responses to find... :wink: ## DRY What is the DRY principle? 1. [ ] Do not drink alcohol when coding > It is mandatory ! 1. [ ] Do not run yourself 1. [x] Do not repeat yourself 1. [ ] Do read yourself ## KISS What is the KISS principle? 1. [ ] Kiss your co-workers when arriving > Not me please. 1. [x] Keep it simple, stupid 1. [ ] Keep it solid, secret 1. [ ] Know I'm shy but serious ## Dependency Inversion What is the Dependency Inversion Principle (DIP) ? 1. [x] A class should depend on abstractions rather than the detail 1. [ ] A class should depend on the detail rather than abstractions > When a coder don't know what to do, he develop an abstraction layer... ## Implement Options What is the cleaner way to implement a choice between 5 options in a class. 1. [ ] FIVE if nested conditions 1. [ ] FIVE if conditions (flat) 1. [ ] ONE switch case 1. [x] polymorphism ## Comments Chose the good answer. Are method comments useful? 1. [ ] always: each method should have its comment > No. Code, variables must be self-comprehensive. 1. [ ] never: I should be able to understand a method without comment > Never is to strong. 1. [ ] most of the time: no comment for accessors but comments for other methods 1. [x] never but in some specific cases: informative comment, explanation of intent, warning > For non-API methode of course ## Arguments What is the best ? 1. [ ] Pass a lot or arguments to a method/function to have every elements > A lot of args is a source of mistakes. 1. [x] Limit arguments number to 4 maximum, and use objects for more ## Boy Scout Rule What does mean the Boy scout rule "Leave the campground cleaner than you found it." in software development? 1. [x] improve the code each time you have the occasion to do it 1. [ ] have a clean development environment 1. [ ] delete code each time you touch to some code ## Magic Numbers Select good definitions of a "magic number" - [x] A number directly in code, like ```if ( a > 12) ...```, and it is bad. - [x] A string directly in code, like ```if ( name == "Alex") ...```, and it is bad. - [ ] A specific number to pass options to the compiler > No this is a **compiler directive** - [ ] A variable name containing a number, like ```a12 = ...``` > 2 good definitions... :wink: ## CamelCase convention Select good variables names in CamelCase - [x] relativePositionInSpace - [ ] relativepositioninspace - [ ] relative_Position_In_Space > This is Snake case - [x] numberOfElementsInBasket - [ ] Numberoffelementsinbasket > Camel case is the practice of writing phrases without spaces or punctuation. The format indicates the separation of words with a single capitalized letter, and the first word starting with either case. ## Conventions Select good conventions for clean code in this list - [ ] Never user Snake case - [ ] Use CamelCase or SnakeCase when you want - [x] Choose beetwen CamelCase and Snake case and never change in the project. - [x] Prefer english language for comment, variables, class... - [x] variables for array, list are in plurial - [x] One file per class - [ ] Most of the time, prefer embedded loops rather than methodes (for performance) > 4 good answers... :wink: ## Good Naming Variable What would be the best name (with respect to clean code) for `int d; // elapsed time in days`? 1. [ ] days > not enought meaningful. 1. [ ] elapsedTime > Can be acceptable if every time unit in the software is in days. 1. [x] elapsedTimeInDays > Right it's a descriptive naming and the comment is useless now. 1. [ ] duration > it is a wrong meaning 1. [ ] durationInDays > it is a wrong meaning > **Meaningful Names** > > - A meaningful name is one of the most important conventions. Always use a meaningful name for variables, functions, and others. Choose a name that expresses the meaning of your purpose. > > - If we need a function that will get the user's bank information, then we must not use a name like getUserInfo or something like that. We should use getUserBankInfo to be more specific. ## Basic Java Clean Code Select the `Java` code snippets which follow principles of clean code - [ ] ```java if (student.classes.length < 7) { // Do something } ``` > `7` is a *magic number* - [ ] ```java const yyyymmdstr = moment().format("YYYY/MM/DD"); ``` > variable name is not meaningful - [x] ```java public Booking book (Customer aCustomer, boolean isPremium) { if(isPremium) // logic for premium book else // logic for regular booking } ``` - [ ] ```java int nusers; // number of users. ``` > Variable name is too short and not meaningful. > **Good Practices for Clean Code** > 1. No Magic Numbers > 2. No Deep Nesting > 3. Missing Comments > 4. Avoid Large Functions > 5. Avoid Code Repetition > 6. Camel Case Variable Naming > 7. Meaningful Names > 8. Descriptive Naming Over Concise > 9. Use Consistent Verbs per Concept > 10. Use Nouns and Pascal Case for Class Name > 11. Capitalize Constant Values > 12. Avoid One-Letter Variable Names ## Clean Javascript Is this code clean (despite it is JS :)) ? ```js class CarouselRightArrow extends Component{ render() { return ( ); } }; ``` 1. [x] YES 1. [ ] NO ## Clean C Is this code clean ? ```Java extern int array_a[]; extern int array_b[]; int sum_a = 0; const NB_ELEMENTS = 4; for (int i = 0; i < NB_ELEMENTS; i++) sum_a += array_a[i]; int average_a = sum_a / NB_ELEMENTS; int sum_b = 0; for (int i = 0; i < NB_ELEMENTS; i++) sum_b += array_b[i]; int average_b = sum_b / NB_ELEMENTS; ``` 1. [x] YES > One letter variables for iterators is allowed 1. [ ] NO ## Java Is it clean ? ```java public class UserValidator { private Cryptographer cryptographer; public boolean checkPassword(String userName, String password) { User user = UserGateway.findByName(userName); if (user != User.NULL) { String codedPhrase = user.getPhraseEncodedByPassword(); String phrase = cryptographer.decrypt(codedPhrase, password); if ("Valid Password".equals(phrase)) { Session.initialize(); return true; } } return false; } } ``` 1. [ ] YES > - "Valid Password" is a *magic number*. > - The test ```if (user != User.NULL)``` must be non negative. 1. [x] NO > - "Valid Password" is a *magic number*. > - The test ```if (user != User.NULL)``` must be non negative.