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

PrincípiosPrincípiosee valoresvalores

“Working software is the primarymeasure of progress.”

PrincípiosPrincípiosee valoresvalores

“Welcome changing requirements,even late in development.”

PrincípiosPrincípiosee valoresvalores

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

NossasNossasresponsabilidades?responsabilidades?

NossasNossasresponsabilidades?responsabilidades?

Traduzir desejos

NossasNossasresponsabilidades?responsabilidades?

Escolher linguagem

Traduzir desejos

NossasNossasresponsabilidades?responsabilidades?

Escolher linguagem Libs/frameworks

Traduzir desejos

NossasNossasresponsabilidades?responsabilidades?

Escolher linguagem

Definir arquitetura

Libs/frameworks

Traduzir desejos

NossasNossasresponsabilidades?responsabilidades?

Escolher linguagem

Garantir qualidade

Definir arquitetura

Libs/frameworks

Traduzir desejos

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

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

Precisamos criar umUsuário com nome e idade

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

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

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

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

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

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

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

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

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

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

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

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

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

$this->logger->log(/* … */);}

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

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

Meu, num dá pra imprimiro último usuário criado?

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

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

ResultadoResultado

ResultadoResultado

Será que “APENAS funcionar” é suficiente?

ResultadoResultado(real)(real)

Bad smellsBad smells

Bad smellsBad smells

Rigidez

Bad smellsBad smells

Rigidez

Fragilidade

Bad smellsBad smells

Rigidez

FragilidadeImobilidade

Bad smellsBad smells

Rigidez

FragilidadeImobilidade

Complexidadedesnecessária

Principles of OODPrinciples of OOD

Principles of OODPrinciples of OOD

Class design

Principles of OODPrinciples of OOD

Class designPackage cohesion

Principles of OODPrinciples of OOD

Class design

Package coupling

Package cohesion

Principles of OODPrinciples of OOD

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 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...

Single ResponsibilitySingle Responsibility

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

Single ResponsibilitySingle Responsibility

class UserRepository{}

Single ResponsibilitySingle Responsibility

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

Single ResponsibilitySingle Responsibility

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() { /* … */ }}

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

Open/closedOpen/closed

Should be able to extendbehaviors, without modifyingthe class

Open/closedOpen/closed

class Authenticator{}

Open/closedOpen/closed

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

Open/closedOpen/closed

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

Open/closedOpen/closed

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?

Open/closedOpen/closed

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...

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

Liskov substitutionLiskov substitution

Derived classes must besubstitutable for their baseclasses

Liskov substitutionLiskov substitution

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

Liskov substitutionLiskov substitution

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

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

Liskov substitutionLiskov substitution

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

Liskov substitutionLiskov substitution

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

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

Liskov substitutionLiskov substitution

Contravariance of method arguments in subtypesCovariance of return types in subtypes

Liskov substitutionLiskov substitution

Contravariance of method arguments in subtypesCovariance of return types in subtypes

Preconditions cannot be strengthened in subtypesPostconditions cannot be weakened in subtypes

Liskov substitutionLiskov substitution

Contravariance of method arguments in subtypesCovariance of return types in subtypes

Preconditions cannot be strengthened in subtypesPostconditions cannot be weakened in subtypes

No new exceptions! Don't violate history constraint

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

Interface segregationInterface segregation

Make fine grained interfacesthat are client specific

Interface segregationInterface segregation

interface UserManager{}

Interface segregationInterface segregation

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

Interface segregationInterface segregation

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);}

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

Dependency InversionDependency Inversion

Depend on abstractions,not on concretions

Dependency InversionDependency Inversion

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

Dependency InversionDependency Inversion

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

SOLID principlesSOLID principles

SOLID principlesSOLID principles

Classes mais coesas

SOLID principlesSOLID principles

Classes mais coesas

Menos acoplamento

SOLID principlesSOLID principles

Classes mais coesas

Menos acoplamento

Menos mudançasem código estável

SOLID principlesSOLID principles

Classes mais coesas

Menos acoplamento

Menos mudançasem código estável

Testes mais fáceis

Dúvidas?Dúvidas?

Obrigado!Obrigado!@lcobucci@lcobucci