Refactor, the third commandment

REFACTOR THE THIRD COMANDEMENT
by Nicola Pietroluongo
@niklongstone
Nicola Pietroluongo @niklongstone

TDD CYCLE

“It s a’ process of restructuring an existing code,
altering its internal structure without changing its
external behavior.”
DEFINITION OF REFACTORING

Code will look clean
Easy to understand
Easy to edit
Easy 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 MEHTOD
CODE DUPLICATION
NO STANDARDS
…..

WHAT'S WRONG...?

WHAT'S WRONG...?
NAMING

WHAT'S WRONG...?
COMPLICATE CONDITIONALS

WHAT'S WRONG...?
SWITCH

WHAT'S WRONG...?
ERROR CODES

WHAT'S WRONG...?
PARAMETERS

WHAT'S WRONG...?
GHOST PARAMETERS

WHY THIS IS BAD?
GHOST PARAMETERS

AT CLASSES / OBJECTS LEVEL
REFACTORING

WHAT'S WRONG...?
DIVERGENT CHANGE

WHAT'S WRONG...?
CONSTRUCTORS

WHY THIS IS BAD?
CONSTRUCTORS

WHAT'S WRONG...?
PRIMITIVE OBSESSION

WHAT'S WRONG...?
MESSAGE CHAIN

WHAT'S WRONG...?
INAPPROPRIATE INTIMACY

WHAT'S WRONG...?
REFUSED BEDQUEST

WHAT'S WRONG...?
TRAITS FREAK
TRICK OR TRAIT

AT APPLICATION / DESIGN LEVEL
REFACTORING

LAZY CLASS
A CLASS DOESN'T DO ENOUGH COULD BE
REMOVED

SHOTGUN SURGERY

DATA ABSTRACTION
DATA ACCESS LAYER
DB
BUSINESS LOGIC LAYER
PRESENTATION LAYER

PARALLEL INHERITANCE HIERARCHIES
Mover
Driver
+openWindows()
Vehicle
+getOperator(Mover)
Car
Motorbike
Rider
+moveHandGrip()

Mover
Driver
+openWindows()
Vehicle
+getOperator(Mover)
Car
Motorbike
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: @niklongstone
Github: github.com/niklongstone
Website: www.nicolapietroluongo.com
Code: github.com/niklongstone/php-refactoring
THANKS

Refactor, the third commandment

Refactor, the third commandment

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