Maintainable + Extensible = Clean ... yes, Code!

Antonio Perić-Mažar 29.10.2016 - #sfcampua Maintainable + Extensible = Clean
... yes, Code!

@antonioperic About me • Antonio Perić-Mažar,   mag. ing. comp.
• CEO, Co-Founder @ Locastic • Co-Founder @ Shift Conference • Software developer, Symfony2 • Open Source Contributor • SFUGCRO  • w: www.locastic.com • m: [email protected] • t: @antonioperic

@antonioperic Locastic • We help clients create amazing web and
mobile apps (since 2011) • design and development agency • mobile development • web development • UX/UI • Training and Consulting • Shift Conference, Symfony Croatia • www.locastic.com • t: @locastic

@antonioperic Locastic

@antonioperic Questions? • Who thinks he is producing good code?
• What is bad code? • What is good code? • Do you know how to measure code quality?

@antonioperic

@antonioperic Note: when we asked for this code we got
it in zip file!!! No VCS at all!

@antonioperic

@antonioperic This was one huge WTFn project!

@antonioperic

@antonioperic Code Smell!!! (Bad Code) • Use globals • Anything
hardcoded (url, ip, etc) • Long classes or methods • Deep structures • Long and bad names • Lack of formatting • Lack of standard

@antonioperic Code Smell!!! (Bad Code) • Overuse of public static
• Too many parameters • Weird order of parameters • GOD Object (he can do everything and he knows everything) • No input validation • No comments

@antonioperic Code Smell!!! (Bad Code) • Takes 1-2 sentences to
explain • Copy-pasted - repetitive code • Never used inheritance, interface or composition • not readable • not testable

@antonioperic Code Smell!!! (Bad Code) • hard to understand •
hard to maintain • gives a headache • you don’t won’t to work on/with it

@antonioperic

@antonioperic Avoid being STUPID Singleton Tight coupling Untestability Premature optimization
Indescriptive naming Duplication

@antonioperic

@antonioperic But why we still doing it… • We are
lazy • Short deadlines • Bad decisions • Fast - good - cheap • We are always the best developer ever :)

@antonioperic Code has expiration date!

@antonioperic Yesterday!

@antonioperic Good developers are shipping! balance shipping vs good code

@antonioperic Developers are evolving!

@antonioperic

@antonioperic Language is evolving • Frameworks (Symfony <3) • Package
managers (composer) • Standards • PHP7

@antonioperic “Any fool can write code that a computer can
understand. Good programmers write code that humans can understand.“ Martin Fowler

@antonioperic CODE

@antonioperic

@antonioperic Clean code • Code that doesn’t exist • KISS
• DRY • SOLID • Don’t reinvent the wheel • Design Patterns • Testable -> Tested

@antonioperic Clean code • Flexible • Maintainable • Easy to
refactor • Readable

@antonioperic Clean code is easy to understand, easy to change
and reusable.

@antonioperic

@antonioperic Why we should care… • Someone else will use
that code • You will use that code • Bad code does a lot of things but none well • You don’t write code just to be there • Maintaining should be easy • Good code save money and time

@antonioperic

@antonioperic If technical debt is not repaid, it can accumulate
'interest', making it harder to implement changes later on.

@antonioperic

@antonioperic Guidance for better (clean) code

@antonioperic #1 Naming matters • Don’t abbreviate • $string->b =
false; • $string->bold = false; • Make code readable • Meaningful names • Improves readability • Good code should be talking to you • You should read it like a book, whitespace is important

@antonioperic #1 Naming matters • Two world words variable name
• $data, $data2 • $total, $total2, $total3

@antonioperic #1 Naming matters

@antonioperic #1 Naming matters • Don’t be silly!

@antonioperic #1 Naming matters • Good name should explain •
why it exist • what it does • how to use it • If you need comment for explain it, it is bad name • Class should use a noun, method a verb

@antonioperic #2 Code standard • Don’t mix styles in project,
use whitespace • Easier to navigate inside project • Less time for boarding new developer • PHP-FIG • Stick with PSR • PSR-0 autoloading • PSR-1 basing code style • PSR-2 detailed coding style

@antonioperic #2 Code standard • Symfony follows the standards defined
in the PSR-0, PSR-1, PSR-2 and PSR-4 documents. • http://symfony.com/doc/current/contributing/ code/standards.html

@antonioperic #3 Use only one level of indentation per method
• {{{ }}} try to avoid this • force single responsibility • small, simple, easier to understand • our mind model is important • separate logic blocks and complex level of indentation into methods

@antonioperic #4 Don’t use else • reduce code complexity •
early returns • use Exceptions • it reduce complex of our mind model • method should not do more then one thing • don’t use intermediate variable • use polymorphism, switch is signal for polymorphism • don’t abuse polymorphism

@antonioperic #4 Don’t use else

@antonioperic #5 Keep your classes/methods small • easier to test
• do one thing, and do one thing well • all functions should return something and avoid returning NULL • keep methods small (max. 20 lines of code) • avoid side-effects • avoid global state

@antonioperic #6 Use Exceptions • Use them • Make sure
to catch them • Specify the nature of the error • throw new InvalidArgumentException(); • Don’t use special error codes

@antonioperic #7 Design patterns • use them, they give you
solution for some well known problems

@antonioperic #8 Use SPL • The Standard PHP Library (SPL)
is a collection of interfaces and classes that are meant to solve common problems. • SPL provides a set of standard datastructure, a set of iterators to traverse over objects, a set of interfaces, a set of standard Exceptions, a number of classes to work with files and it provides a set of functions like spl_autoload_register()

@antonioperic #8 Use SPL • Datastructures • SplDoublyLinkedList — The
SplDoublyLinkedList class • SplStack — The SplStack class • SplQueue — The SplQueue class • SplHeap — The SplHeap class • SplMaxHeap — The SplMaxHeap class • SplMinHeap — The SplMinHeap class • SplPriorityQueue — The SplPriorityQueue class • SplFixedArray — The SplFixedArray class • SplObjectStorage — The SplObjectStorage class

@antonioperic #8 Use SPL • Iterators • AppendIterator — The
AppendIterator class • ArrayIterator — The ArrayIterator class • CachingIterator — The CachingIterator class • CallbackFilterIterator — The CallbackFilterIterator class • DirectoryIterator — The DirectoryIterator class • EmptyIterator — The EmptyIterator class • FilesystemIterator — The FilesystemIterator class • FilterIterator — The FilterIterator class • GlobIterator — The GlobIterator class • InfiniteIterator — The InfiniteIterator class • …

@antonioperic #8 Use SPL • Interfaces • Countable — The
Countable interface • OuterIterator — The OuterIterator interface • RecursiveIterator — The RecursiveIterator interface • SeekableIterator — The SeekableIterator

@antonioperic #8 Use SPL • Exceptions • BadFunctionCallException — The
BadFunctionCallException class • BadMethodCallException — The BadMethodCallException class • DomainException — The DomainException class • InvalidArgumentException — The InvalidArgumentException class • LengthException — The LengthException class • LogicException — The LogicException class • OutOfBoundsException — The OutOfBoundsException • OutOfRangeException — The OutOfRangeException • OverflowException — The OverflowException • RangeException — The RangeException • RuntimeException — The RuntimeException • UnderflowException — The UnderflowException • UnexpectedValueException — The UnexpectedValueException class

@antonioperic #9 Law of demeter (LoD) • Each unit should
have only limited knowledge about other units: only units "closely" related to the current unit. • Each unit should only talk to its friends; don't talk to strangers. • Only talk to your immediate friends • Help you build code that is easier to test

@antonioperic #9 Law of demeter

@antonioperic #9 Law of Demeter

@antonioperic #9 Law of demeter (LoD) • Benefits: • Keep
object instant ion simple • Easier to mock objects • Simplify dependency graph

@antonioperic #10 Comments • Good comments • Bad comments •
PHPDoc • Don’t use comments for tracking history of changes

@antonioperic #11 Use tools • PHPCS • PHP-CS-Fixer • pDepend
(performs static code analysis) • PHPLOC (A tool for quickly measuring the size of a PHP project) • SensioLabs Insight • phpmd (mess detector) • PHPCPD (copy paste detector) • PHPDCP (dead code detector) • learn more about your IDE (PHPStorm is amazing tool)

@antonioperic #12 improve yourself • read a lot of code
• http://www.livecoding.tv/ • work in pairs • do open source - you will get a lot of free reviews from amazing developers • show your code to other developers • go to conferences • be responsive for your code

@antonioperic “I live and breathe my code and my code
is mostly the fun stuff. You know the logic, the stuff that makes cool applications, right?.“ Misko Havery

@antonioperic #11 Boy-scout rule

@antonioperic #12 Boy scout rule • Always check a module
in cleaner than when you checked it out. • Always leave code in better shape then you found it

@antonioperic Conclusion • Clean code is: • structured • simple
• consistent • Use boy scout rule • Do small steps • There is no silver bullet only hard work

@antonioperic References • https://cleancoders.com/ • Clean Code: A Handbook of
Agile Software Craftsmanship, Robert C. Martin • Dotting Your I’s and Crossing Your T7s, Juliette Reinders Folmer, IPC Sprint 2015 • Your code sucks, let's fix it - By Rafael Dohms • Clean Code, Tobias Schlitt, WebSummerCamp 2016 • Google Tech Talks, Clean Code • https://www.youtube.com/watch?v=HZJxjlvBbVA, Clean Code, David Donahue • Plenty of other talks at Youtube

@antonioperic Thank you! www.locastic.com [email protected] @antonioperic 

Maintainable + Extensible = Clean ... yes, Code!

Maintainable + Extensible = Clean ... yes, Code!

More Decks by Antonio Peric-Mazar

Other Decks in Programming

Featured

Transcript