refactor, the third commandment

REFACTOR THE THIRD COMANDEMENTby Nicola Pietroluongo

@niklongstone

Nicola Pietroluongo @niklongstone


TDD CYCLE

Its a process of restructuring an existing code, altering its internal structure without changing its external behavior.


DEFINITION OF REFACTORING

Code will look cleanEasy to understandEasy to editEasy to mantain


WHY REFACTORING?


WHAT TO DO BEFORE

Announce the refactoring

Build a sandbox environment

Use a version control system (Git)

Remember coding standards

Remember OO design principle SOLID

Write or improve the test


COMMON REFACTORINGS

Change Signature

Extract (Method, Variable, ...)

Pull Members up

Push Members down

Rename

Safe Delete

UNDERSTAND THE BEHAVIOUR


HOW TO START A REFACTORING

USE AN IDE



START TO INSPECT




LEVEL OF REFACTOR

FUNCTIONS/
METHODS

CLASSES/OBJECTS

APPLICATION/DESIGN

AT FUNCTION / METHOD LEVEL


REFACTORING


WHAT'S WRONG...?


WHAT'S WRONG...?

LONG MEHTODCODE DUPLICATIONNO STANDARDS..

WHAT'S WRONG...?


WHAT'S WRONG...?


NAMING

WHAT'S WRONG...?


NAMING

WHAT'S WRONG...?


WHAT'S WRONG...?


COMPLICATE CONDITIONALS

WHAT'S WRONG...?


COMPLICATE CONDITIONALS

WHAT'S WRONG...?


WHAT'S WRONG...?


SWITCH

WHAT'S WRONG...?


SWITCH

WHAT'S WRONG...?


WHAT'S WRONG...?


ERROR CODES

WHAT'S WRONG...?


ERROR CODES

WHAT'S WRONG...?


WHAT'S WRONG...?


PARAMETERS

WHAT'S WRONG...?


PARAMETERS

WHAT'S WRONG...?


WHAT'S WRONG...?


GHOST PARAMETERS

WHY THIS IS BAD?


GHOST PARAMETERS

AT CLASSES / OBJECTS LEVEL


REFACTORING

WHAT'S WRONG...?


WHAT'S WRONG...?


DIVERGENT CHANGE

WHAT'S WRONG...?


DIVERGENT CHANGE

WHAT'S WRONG...?


WHAT'S WRONG...?


CONSTRUCTORS

WHY THIS IS BAD?


CONSTRUCTORS

WHAT'S WRONG...?


WHAT'S WRONG...?


PRIMITIVE OBSESSION

WHAT'S WRONG...?


PRIMITIVE OBSESSION

WHAT'S WRONG...?


WHAT'S WRONG...?


MESSAGE CHAIN

WHAT'S WRONG...?


MESSAGE CHAIN

WHAT'S WRONG...?


WHAT'S WRONG...?


INAPPROPRIATE INTIMACY

WHAT'S WRONG...?


INAPPROPRIATE INTIMACY

WHAT'S WRONG...?


WHAT'S WRONG...?


REFUSED BEDQUEST

WHAT'S WRONG...?


REFUSED BEDQUEST

WHAT'S WRONG...?


WHAT'S WRONG...?


TRAITS FREAKTRICK OR TRAIT

WHAT'S WRONG...?


TRAITS FREAKTRICK OR TRAIT

AT APPLICATION / DESIGN LEVEL


REFACTORING

LAZY CLASS


A CLASS DOESN'T DO ENOUGH COULD BE REMOVED

SHOTGUN SURGERY


DATA ABSTRACTION


DATA ACCESS LAYERDBBUSINESS LOGIC LAYERPRESENTATION LAYER

PARALLEL INHERITANCE HIERARCHIES


MoverDriver+openWindows()Vehicle+getOperator(Mover)CarMotorbike

Rider+moveHandGrip()



MoverDriver+openWindows()Vehicle+getOperator(Mover)CarMotorbike

Rider+moveHandGrip()

Pilot+moveFlaps()Plane



Mover+accelerate()+brake()Vehicle+setFuel()CarTrip__construct(Driver)+accelerate()+openWindow()...MotorbikeTrip__construct(Rider)+accelerate()+brake()...

RESPONSIBILITY


Check constructors, extends and implements
Composition over inheritance

Check namespacing and folder structure

SOME TOOL


REFACTORING

$ sed -i 's/UglyClass/PrettyClass/g' /folder/myfile.php

$ find /folder/src -type f -exec \ sed -i 's/UglyClass/PrettyClass/g' {} \;


SED


PHPCS (and phpcbf)


PHPUNIT + XDEBUG (Change Risk Analyzer and Predictor)


XHPROF

$ phpmd src/ text design,codesize

$ /src/File.php:26 The class File has 12 methods. Consider refactoring File to keep number of methods under 10.


PHPMD


PhpMetrics

Scisr (http://iangreenleaf.github.io/Scisr/)

Rephactor (http://rephactor.sourceforge.net/user-guide.php)

phpdepend.org

phpqatools.org

https://github.com/ziadoz/awesome-php#code-analysis


OTHER RESOURCES


THANKS

IMPROVE THE CODE, IMPROVE YOURSELF

Twitter: @niklongstoneGithub: github.com/niklongstoneWebsite: www.nicolapietroluongo.com

Code: github.com/niklongstone/php-refactoring


THANKS

refactor, the third commandment

Software