make it solid!

Make itMake itSOLID!SOLID!

Luís Otávio Cobucci OblonczykLuís Otávio Cobucci Oblonczyk@lcobucci@lcobucci

Luís OtávioLuís OtávioCobucci OblonczykCobucci Oblonczyk

@lcobucci@lcobucci

PrincípiosPrincípiosee valoresvalores


“Working software is the primarymeasure of progress.”


“Welcome changing requirements,even late in development.”


“Continuous attention to technical excellence and good design enhances agility.”

NossasNossasresponsabilidades?responsabilidades?


Traduzir desejos


Escolher linguagem

Traduzir desejos


Escolher linguagem Libs/frameworks

Traduzir desejos


Escolher linguagem

Definir arquitetura

Libs/frameworks

Traduzir desejos


Escolher linguagem

Garantir qualidade

Definir arquitetura

Libs/frameworks

Traduzir desejos

Coisas que nuncaCoisas que nuncaocorrem... né?ocorrem... né?


Precisamos criar umUsuário com nome e idade

class UserCreator{ public function create($name, $age) { /*... */ }}


public function __construct() { $this->conn = new PDO( 'mysql:host=127.0.0.1;dbname=awesome', 'root', 'ImAGenius' );}


public function create($name, $age) { $stm = $this->conn->prepare('...'); $stm->execute([$name, $age]);}



Agora, temos que logar no arquivo /tmp/users.log, adicionandoo responsável pelo cadastro

class UserCreator{ public function create($name, $age, $responsible) { /*... */ }}


public function __construct() { // (…) $this->logger = new FileLogger();}


public function create($name, $age, $responsible) { $stm = $this->conn->prepare('...'); $stm->execute([$name, $age]);

$this->logger->log(/* … */);}



Meu, num dá pra imprimiro último usuário criado?

class UserCreator{ public function create($name, $age, $responsible) { /*... */ } public function print() { /* … */ }}


ResultadoResultado

ResultadoResultado

Será que “APENAS funcionar” é suficiente?

ResultadoResultado(real)(real)

Bad smellsBad smells


Rigidez


Rigidez

Fragilidade


Rigidez

FragilidadeImobilidade


Rigidez

FragilidadeImobilidade

Complexidadedesnecessária

Principles of OODPrinciples of OOD


Class design


Class designPackage cohesion


Class design

Package coupling

Package cohesion


Class design

Package coupling

Package cohesion

S.O.L.I.D.S.O.L.I.D.

Single Responsibility principle

Open/Closed principle

Liskov substitution principle

Interface segregation principle

Dependency inversion principle

S.O.L.I.D. principlesS.O.L.I.D. principles

Single ResponsibilitySingle Responsibility

One does not simplyhave more than a reasonto modify a class...


A class should have one,and only one, reasonto change.


class UserRepository{}


class UserRepository{ public function findByAge($age) { /* … */ } public function findByName($name) { /* … */ }}


class UserRepository{ public function findByAge($age) { /* … */ } public function findByName($name) { /* … */ } public function pdfReport() { /* … */ }}

Single ResponsibilitySingle Responsibilityclass UserRepository{ public function findByAge($age) { /* … */ } public function findByName($name) { /* … */ }}

class UserReport{ public function generate() { /* … */ }}

Open/closedOpen/closed

Should be able to extendbehaviors, without modifyingthe class


class Authenticator{}


class Authenticator{ public function authenticate($login, $passwd) { /* … */ }}


class Authenticator{ public function authenticate($login, $passwd) { /* … */ } private function findUser($login) { /* finds on DB */ } private function matchPasswd(User $user, $passwd) { /* … */ }}


class Authenticator{ public function authenticate($login, $passwd) { /* … */ } private function findUser($login) { /* finds on DB */ } private function matchPasswd(User $user, $passwd) { /* … */ }}

E se precisarmos buscarem outro lugar?


class Authenticator{ public function authenticate($login, $passwd) { /* … */ } protected function findUser($login) { /* finds on DB */ } private function matchPasswd(User $user, $passwd) { /* … */ }}

Assim podemos sobrescrevero método de busca...

Liskov substitutionLiskov substitution

Derived classes must besubstitutable for their baseclasses


class Rectangle{ public function setX($x) { /* … */ } public function setY($y) { /* … */ } public function getArea() { /* … */ }}


function getArea($x, $y, Rectangle $object){ $object->setX($x); $object->setY($y); return $object->getArea(); }

getArea(5, 10, new Rectangle());


class Square extends Rectangle{ public function setX($x) { /* also setY() */ } public function setY($y) { /* also setX() */ }}


function getArea($x, $y, Rectangle $object){ $object->setX($x); $object->setY($y); return $object->getArea(); }

getArea(5, 10, new Square());


Contravariance of method arguments in subtypesCovariance of return types in subtypes



Preconditions cannot be strengthened in subtypesPostconditions cannot be weakened in subtypes



Preconditions cannot be strengthened in subtypesPostconditions cannot be weakened in subtypes

No new exceptions! Don't violate history constraint

Interface segregationInterface segregation

Make fine grained interfacesthat are client specific


interface UserManager{}


interface UserManager{ public function create($name, $email); public function remove($id); public function find($id); public function findByName($name);}


class UserController{ public function find($id) { /* … */ }

/** @return UserManager */ public function getManager();}

Interface segregationInterface segregationinterface UserManager{ public function create($name, $email); public function remove($id);}

interface UserLocator{ public function find($id); public function findByName($name);}

Dependency InversionDependency Inversion

Depend on abstractions,not on concretions


public function __construct( DatabasePersister $persister, FileNotifier $notifier) { $this->persister = $persister; $this->notifier = $notifier;}


public function __construct(Persister $persister, Notifier $notifier){ $this->persister = $persister; $this->notifier = $notifier;}

SOLID principlesSOLID principles


Classes mais coesas


Classes mais coesas

Menos acoplamento


Classes mais coesas

Menos acoplamento

Menos mudançasem código estável


Classes mais coesas

Menos acoplamento

Menos mudançasem código estável

Testes mais fáceis

Dúvidas?Dúvidas?

Obrigado!Obrigado!@lcobucci@lcobucci

make it solid!

Technology

public function findbyage

public function findbyname

public function print

public function pdfreport

private function finduser

class usercreator

modifyingthe class

class userreport