## 7 Golden Rules of Clean, Simple and Maintainable Code
---
Created by [Sumit Chhetri](https://www.facebook.com/SHhetri) / [@shhetri](https://twitter.com/shhetri)
[YIPL](http://younginnovations.com.np/) , Kumaripati, Lalitpur
## Why Write clean code ?
### Code for humans not machines
#### Think that the next person who reads your code is [Ghas Katne Khurkera](https://www.youtube.com/watch?v=kKVp6ytaJJA) ko bhoot.
#### If you don't write clean code, he will follow you to the end.
### Rule 1: Follow a consistent coding standard
* If you are doing PHP follow [PSR-2](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide.md)
* Other languages like Java, Python, Javascript also have coding standards
* Use a linter or CS fixer to follow the standard. Integrate build tools in Sublime or use default PHPStrom code refactor, to automate this
* Makes it easy for everyone - including yourself - in the team, to read the code
### Rule 2: Name things properly, long variable and function/method names are allowed
* Stick to one convention. ($someVariable or $SomeVariable or $some_variable)
* Don't use abbreviations, may not be understandable to the person, who reads your code
* Naming is difficult, do it well. Name classes, variables and methods that make sense
* Do not be redundant.
* [Example](https://gist.github.com/shhetri/bb6dd1981267eb3a4cf4#file-rule-php-L3)
### Rule 3: Be expressive, write code as you speak and be optimally verbose
* Focus on API rather than patterns.
* Frist, write down the API for perfect scenario, observe how it feels, then jump to coding and make it work.
* Tell, don't ask.
* [Example](https://gist.github.com/shhetri/bb6dd1981267eb3a4cf4#file-rule-php-L28)
### Rule 4: Max indent per method should be 2, in case of exceptions 3
* Avoid the use of else.
* Extract the logic to other readable method.
* Return early
* Throw exception
* [Example](https://gist.github.com/shhetri/bb6dd1981267eb3a4cf4#file-rule-php-L60)
* also mention if you access property of a property a->b->c->d() there something wrong
* create wrapper for it.
### Rule 5: Avoid creating [god object](https://en.wikipedia.org/wiki/God_object) and long methods
* One class should do one thing not everything like `StatusChanger` or `StatusManager` not `StatusGod`
* Avoid using **`and`** in method names like **`validateAndSave`**, one method needs to do one thing and one thing well
* Keep methods small, a 50 line method is a problem
* Keep classes small, a 1000 line class is a pain
* Keep the instance variables to as low as 6 or 7.
### Rule 6: Keep the method in one place, inject the class and call it, [DRY](https://en.wikipedia.org/wiki/Don%27t_repeat_yourself)
* In MVC keep controllers slim, business logic belongs to services or repositories, check [symfony best practice](http://symfony.com/doc/current/best_practices/controllers.html) for controller 5-10-20
* If you access property of a property a->b->c->d() there is something wrong, you can use a wrapper or proxy function.
* Use language constructs like interfaces, traits to make code more expressive and reusable
* If you find yourself copying the same code several times, extract that code into its own method.
* Refactor your code, every once in a while.
* [Example](https://gist.github.com/shhetri/bb6dd1981267eb3a4cf4#file-rule-php-L145)
### Rule 7: Avoid in-line comments (comment with code), put comments in the method doc
* Comment is a code smell (anti pattern), like [here](https://github.com/younginnovations/aidstream/blob/master/application/modules/simplified/models/Simplified.php#L38)
* If you need to write comments to explain your code, it means you need to put it in a new method.
* [Example](https://gist.github.com/shhetri/bb6dd1981267eb3a4cf4#file-rule-php-L247)
```
public function addActivity($data , $default)
{
$this->defaults = $default;
$identity = Zend_Auth::getInstance()->getIdentity();
//var_dump($data);exit;
$model = $this->model;
$modelActivity = new Model_Activity();
$activitiesId = $model->getIdByField('iati_activities', 'account_id', $identity->account_id);
//Create activity and its defaults
$iatiIdentifier['activity_identifier'] = $data['identifier'];
```
### Other considerations
* Consider using DTO (Data Transfer Object)
* Avoid working with just arrays for large data sets, use class and type hint
* Rather than starting to write something on your own spend 5 minutes to read the framework/library documentation to know if its already provided
* Extract out methods and rename variables as necessary
* Read about cyclomatic complexity and N-Path complexity, [here](http://modess.io/2013/05/19/cyclomatic-and-npath-complexity-explained/)
### Recap 1
* Rule 1: Follow a consistent coding standard
* Rule 2: Name things properly, long variable and function names are allowed
* Rule 3: Be expressive, write code as you speak and be optimally verbose
* Rule 4: Max indent per method should be 2, in case of exceptions 3
### Recap 2
* Rule 5: Avoid creating [god object](https://en.wikipedia.org/wiki/God_object) and long methods
* Rule 6: Keep the method in one place, inject the class and call it, [DRY](https://en.wikipedia.org/wiki/Don%27t_repeat_yourself)
* Rule 7: Avoid in-line comments (comment with code), put comments in the method doc
* Don't forget the consideration and reading
PS: you can print the recap slides and mug them up.
### References
* Most code examples are taken from YIPL open source code on Github.
* [Rules for simpler code - laracast](https://laracasts.com/series/simple-rules-for-simpler-code/episodes/3)
* [Maintainable Code](https://www.justsoftwaresolutions.co.uk/articles/maintainable_code.html)
* [Readable Code](http://werve.net/articles/writing-readable-code/)
* [Object Calisthenics](http://williamdurand.fr/2013/06/03/object-calisthenics/)
* [Your code sucks - let fix it](http://www.slideshare.net/rdohms/your-code-sucks-lets-fix-it-15471808)
* [PROGRAMMING GUIDELINES (FOR PHP DEVELOPERS) - PART 1: REDUCING COMPLEXITY](https://www.ibuildings.nl/blog/2016/01/programming-guidelines-php-developers-part-1-reducing-complexity)
* [CODING HORROR - Flattening Arrow Code](http://blog.codinghorror.com/flattening-arrow-code/)
### Thanks
#### [Mr. Geshan Manandar](http://geshan.com.np)
#### [PHP Developers Nepal](https://www.facebook.com/groups/109070762572263/) Community
### Any Questions?
#### Remember, simple, understandable, readable and eventually maintainable code is greater than any pattern ever invented (be practical).
