solid: bom design em orientação a objetos

Trilha PHP – SOLIDBom Design em Orientação a Objetos

Mario RezendeDesenvolvedor PHP na Kanui.com.br

Integrante do Grupo de Usuários PHPSP.org.br

❖ Bom Design em OO

❖ Os Princípios do SOLID

❖ Onde o SOLID se “encaixa”

❖ Exemplos de Código

❖ Bônus: Robert Martin & Livros

Agenda

Bom Design em OO

Mudança , Dependência , Acoplamento

1. Mudança de Requisitos

2. Gestão de Dependências

Bom Design em OO

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class AnotherClass{ public function doSomething() { // logic }}

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class Controller{ public function action() { $myClass = new MyClass(); $result = $myClass->myMethod();

$this->render($result); }}

class MyClass{ public function myMethod() { $otherClass = new AnotherClass(); x $anyThing = $otherClass->doSomething();

// solves some logic and returns the result }}


Bom Design em OO


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1 class ClassA { // depends AnotherClass }

1 class ClassB { // depends AnotherClass }

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class Controller{ public function action() { $myClass = new MyClass(); $result = $myClass->myMethod();




Bom Design em OO


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class Controller{ public function action() { $myClass = new MyClass(); $otherClass = new AnotherClass();xxx xxxxxx $result = $myClass->myMethod($otherClass);


class MyClass{ public function myMethod(AnotherClass $class) { $anyThing = $class->doSomething();


Bom Design em OO


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class Controller{ public function action() { $myClass = new MyClass(); $otherClass = new DerivedClass();xxxxxx xxx $result = $myClass->myMethod($otherClass);




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class DerivedClass extends AnotherClass x{ public function doSomething() { // logic }}

Bom Design em OO


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class MyClassTest extends PHPUnit_Framework_TestCase{ public function testMyMethod() { $class = new MyClass(); $this->assertEquals(1, $class->myMethod()); }}

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Este teste irá passar

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Bom Design em OO


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class MyClassTest extends PHPUnit_Framework_TestCase{ public function testMyMethod() { // Create a stub for the AnotherClass class. $stub = $this->getMock('AnotherClass'); x

// Configure the stub. $stub->expects($this->any()) ->method('doSomething') ->will($this->returnValue('mon')); x

$class = new MyClass(); $this->assertEquals(1, $class->myMethod($stub)); }}

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Bom Design em OO

Manifesto para Desenvolvimento

ÁGIL de Software

Mudança , Dependência , Acoplamento , Ágil

Indivíduos e interaçõesSoftware em funcionamento

Colaboração com o cliente

Responder a Mudanças

Os Princípios do SOLID

S ingle Responsibility

Open / Closed

L iskov Substitution

I nterface Segregation

Dependency Inversion

Mudança , Dependência , Acoplamento , Ágil

Princípios Orientação Objetos

AbstraçãoEncapsulamentoHerançaComposiçãoModularidadePolimorfismo

Princípios de Design de Classe

Padrões de Design

Arquitetura em Camadas

Arquitetura Distribuída

SOAESB

SaaS

Mudança , Dependência , Acoplamento , Ágil , Composição , Interface

implementação conceitual

Coesão< AcoplamentoOrtogonalidadeDesign p/ ContratoLei de Deméter

MVCDDDFrameworks

Solução GenéricaProblemas RecorrentesPrograme p/ InterfacePrefira Composição

Onde o SOLID se “encaixa”

Princípios Orientação Objetos

AbstraçãoEncapsulamentoHerançaComposiçãoModularidadePolimorfismo

Princípios de Design de Classe

Padrões de Design

Arquitetura em Camadas

Arquitetura Distribuída

SOAESB

SaaS

Coesão< AcoplamentoOrtogonalidadeDesign p/ ContratoLei de Deméter


SOLID

implementação conceitual

MVCDDDFrameworks

Solução GenéricaProblemas RecorrentesPrograme p/ InterfacePrefira Composição

Onde o SOLID se “encaixa”


Single ResponsibilityUma Classe deve ter uma única razão para mudar

(responsabilidade única)

Exemplos de Código S.O.L.I.D


Single Responsibility1234567891011121314151617181920

class Customer{ public function authenticate() { // authenticate user in a database }

public function hasRole($role) { // checks user privileges }

public function setEmail($email) {}

public function getEmail() {}

public function setPassword($password) {}

public function getPassword() {}}

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class AccessControlManager{ public function __construct(Customer $customer) { //save reference }

public function login() { if ($this->customer->authenticate() && $this->customer->hasRole('user')) { return true; }

return false; }}

S.O.L.I.D



class AccessControlManager{ public function __construct(Customer $customer, Security $secur) { //save references }

public function login() { if ($this->secur->authenticate($this->customer) && $this->secur->hasRole('user', $this->customer)) { return true; }

return false; }}

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class Customer{ public function setEmail($email) {}




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class Security{ public function authenticate(Customer $customer) { // authenticate user in a database }

public function hasRole($role, Customer $customer) { // checks user privileges }}

S.O.L.I.D







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class Sign{ public function authenticate(Customer $customer) { // authenticate user in a database }}

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class Grant{ public function hasRole($role, Customer $customer) { // checks user privileges }}

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class AccessControlManager{ public function __construct(Customer $customer, Sign $sign, Grant $grant) { //save references }

public function login() { if ($this->sign->authenticate($this->customer) && $this->grant->hasRole('user', $this->customer)) { return true; }

return false; }}

S.O.L.I.D


Conclusão❖ SRP é o mais simples, e o mais difícil de fazer certo

Finding and separating those responsibilities is much of whatsoftware design is really about. Indeed, the rest of the principles

we discuss come back to this issue in one way or another.(Robert Martin)

Single Responsibility S.O.L.I.D


Open / ClosedEntidades (classes, módulos, etc) devem ser

aberta para extensão, mas fechada para modificação



Open / Closed S.O.L.I.D12345678910





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return false; }}







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return false; }}

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class SignFacebook extends Sign x{ public function authenticate(Customer $customer) { // connect to third-party server resource }}







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return false; }}

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class Sign { public function authenticate(Customer $customer) { // authenticate user in a database }

protected function getRepository(Adapter $db) x { // connect to database }}

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class SignFacebook extends Sign { public function authenticate(Customer $customer) { // connect to third-party server resource }

protected function getAccessToken(Oauth $client) { // retrieve a valid token }}







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class AccessControlManager{ public function __construct(Customer $customer, SignService $sign, Grant $grant) { // references }

public function login() { if ($this->sign->authenticate($this->customer) && $this->grant->hasRole('user', $this->customer)) { return true; } return false; }}

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class SignDatabase implements SignService { x public function authenticate(Customer $customer) { // authenticate user against a database }

protected function getRepository(Adapter $db) { // connect to database }}

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class SignFacebook implements SignService { x public function authenticate(Customer $customer) { // connect to third-party server resource }


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interface SignService x { public function authenticate(Customer $customer);}


Conclusão❖ OCP está no coração do Design Orientado a Objetos

❖ Flexibilidade, Reutilização e Manutenibilidade

Nor is it a good idea to apply rampant abstractionto every part of the application…

Resisting premature abstraction is as important as abstraction itself.(Robert Martin)

Open / Closed S.O.L.I.D

Dependency Inversion A. Módulos de Alto nível não devem depender de módulos de Baixo nível, ambos devem depender de Abstrações

B. Abstrações não devem depender de detalhes, Detalhes devem depender de Abstrações




S.O.L.I.D12345678910





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class AccessControlManager{ public function __construct(Customer $customer, SignService $sign, Grant $grant) { // references }

public function login() { if ($this->sign->authenticate($this->customer) && $this->grant->hasRole('user', $this->customer)) { return true; } return false; }}

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class SignDatabase implements SignService { public function authenticate(Customer $customer) { // authenticate user against a database }


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interface SignService{ public function authenticate(Customer $customer);}

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Dependency Inversion


Dependency Inversion S.O.L.I.D


A. Módulos de Alto nível não devem depender de módulos de Baixo nível, ambos devem depender de Abstrações



Policy

Mechanism

A. Módulos de Alto nível não devem depender de módulos de Baixo nível, ambos devem depender de Abstrações



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class Customer implements User{ public function setEmail($email) {}




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class SignDatabase implements SignService { public function authenticate(Customer $customer) { // authenticate user against a database }}

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interface SignService{ public function authenticate(Customer $customer);}

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interface GrantService{ public function hasRole($role, Customer $customer)}

1 interface User { // Getter & Setters }

Dependency Inversion S.O.L.I.D12345678910111213

class AccessControlManager{ public function __construct(User $user, SignService $sign, GrantService $grant) { // refs }

public function login() { if ($this->sign->authenticate($this->user) && $this->grant->hasRole('user', $this->user)) { return true; } return false; }}

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class BaseGrant implements GrantService { public function hasRole($role, Customer $customer) { // checks user privileges }}


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class SignDatabase implements SignService { public function authenticate(User $user) { // authenticate user against a database }}

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interface SignService{ public function authenticate(User $user);}

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interface GrantService{ public function hasRole($role, User $user);}

1 interface User { // Getter & Setters }

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class BaseGrant implements GrantService { public function hasRole($role, User $user) { // checks user privileges }}



Policy

Mechanism



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return false; }}




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interface GrantService{ public function hasRole($role, User $user);}

1 interface User { // Getter & Setters }12345678910111213



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class BaseGrant implements GrantService { public function hasRole($role, User $user) { // checks user privileges }}

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class SignDatabase implements SignService { public function authenticate(User $user) { // authenticate user against a database }


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interface SignService { public function authenticate(User $user); protected function getRepository(Adapter $db);}



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interface SignService { public function authenticate(User $user); protected function getRepository(Adapter $db);}

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class SignFacebook implements SignService { public function authenticate(User $user) { // connect to third-party server resource }




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interface SignService{ public function authenticate(User $user);}

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class SignFacebook implements SignService { public function authenticate(User $user) { // connect to third-party server resource }




Policy

Mechanism



Policy

Utility

Mechanism


Conclusão❖ Regras e detalhes devem depender de abstrações,

que são definidas do ponto de vista do uso

❖ Quando as abstrações e detalhes estão isolados, é mais fácil de dar manutenção no código

... inversion of dependencies is the hallmark of good object-oriented design.(Robert Martin)




Liskov SubstitutionPossibilidade de Substituir a Classe Base pela sua Derivada,

sem alterar o funcionamento correto do Software



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class PaymentCalculator{ public function calculatePayday(Payment $pay) { $calendar = $this->getBrazilianCalendar(); $workDays = $this->getWorkDays($calendar); // calculate 5+ days: 2013-10-06 Sunday // find NEXT work day: 2013-10-07 Monday return new DateTime('2013-10-07'); }}

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class Payment{ private $type; //CreditCard, Billet private $amount; private $createdAt; //2013-10-01 Tue private $payday;}

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class PaymentManager{ public function __construct(Payment $payment, PaymentCalculator $calc) { // save references }

public function schedulePayment() { $payday = $this->calc->calculatePayday($this->payment); $this->payment->setPayday($payday); // save in database }}

Liskov Substitution S.O.L.I.D


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class PaymentCalculator{ public function calculatePayday(Payment $pay) { $calendar = $this->getBrazilianCalendar(); $workDays = $this->getWorkDays($calendar); // calculate 5+ days: 2013-10-06 Sunday // find NEXT work day: 2013-10-07 Monday return new DateTime('2013-10-07'); }}

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class PaymentCalcBefore extends PaymentCalculator{ public function calculatePayday(Payment $pay) { $calendar = $this->getBrazilianCalendar(); $workDays = $this->getWorkDays($calendar); // calculate 5+ days: 2013-10-06 Sunday // find PREV work day: 2013-10-04 Friday return date('2013-10-04'); }}

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class PaymentCalcBefore extends PaymentCalculator{ /** @return String */ x public function calculatePayday(Payment $pay) { $calendar = $this->getBrazilianCalendar(); $workDays = $this->getWorkDays($calendar); // calculate 5+ days: 2013-10-06 Sunday // find PREV work day: 2013-10-04 Friday return date('2013-10-04'); }}

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class PaymentCalculator{ /** @return DateTime */ x public function calculatePayday(Payment $pay) { $calendar = $this->getBrazilianCalendar(); $workDays = $this->getWorkDays($calendar); // calculate 5+ days: 2013-10-06 Sunday // find NEXT work day: 2013-10-07 Monday return new DateTime('2013-10-07'); }}

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class PaymentCalcBefore extends PaymentCalculator{ /** @return DateTime */ x public function calculatePayday(Payment $pay) { $calendar = $this->getBrazilianCalendar(); $workDays = $this->getWorkDays($calendar); // calculate 5+ days: 2013-10-06 Sunday // find PREV work day: 2013-10-04 Friday return new DateTime('2013-10-04'); }}

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class PaymentCalculator{ /** @return DateTime */ x public function calculatePayday(Payment $pay) { $calendar = $this->getBrazilianCalendar(); $workDays = $this->getWorkDays($calendar); // calculate 5+ days: 2013-10-06 Sunday // find NEXT work day: 2013-10-07 Monday return new DateTime('2013-10-07'); }}

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class PaymentCalcBefore extends PaymentCalculator { protected function resolvePayDay($workDays,$pay) { // calculate D+5 and find PREVIOUS work day return new DateTime('2013-10-04'); // Friday }}

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class PaymentCalculator { public function calculatePayday(Payment $pay) { $calendar = $this->getBrazilianCalendar(); $workDays = $this->getWorkDays($calendar); return $this->resolvePayDay($workDays, $pay); }

protected function resolvePayDay($workDays,$pay) { // calculate D+5 and find NEXT work day return new DateTime('2013-10-07'); // Monday }}

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class BeforeCalculator extends PaymentCalculator{ protected function resolvePayDay($workDays,$pay) { return new DateTime('2013-10-04'); // Friday }}

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abstract class PaymentCalculator{ public function calculatePayday(Payment $pay) { $calendar = $this->getBrazilianCalendar(); $workDays = $this->getWorkDays($calendar); return $this->resolvePayDay($workDays,$payment); }

abstract protected function resolvePayDay($wd,$p);}

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class AfterCalculator extends PaymentCalculator{ protected function resolvePayDay($workDays,$pay) { return new DateTime('2013-10-07'); // Monday }}

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class CCardPayment implements Payment{ // attributes and methods }

1 interface Payment { }

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class BilletPayment implements Payment { // attributes and methods }



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class CreditCardCalculator extends PaymentCalculator{ protected function resolvePayDay($workDays,$pay) { return new DateTime('2013-10-04'); // Friday }}

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abstract class PaymentCalculator{ public function calculatePayday(Payment $pay) { $calendar = $this->getBrazilianCalendar(); $workDays = $this->getWorkDays($calendar); return $this->resolvePayDay($workDays,$payment); }

abstract protected function resolvePayDay($wd,$p);}

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class BilletCalculator extends PaymentCalculator{ protected function resolvePayDay($workDays,$pay) { return new DateTime('2013-10-07'); // Monday }}

1 interface Payment { }

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class CCardPayment implements Payment{ // attributes and methods }

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class BilletPayment implements Payment { // attributes and methods }



Conclusão❖ LSP é o principal facilitador do OPC

❖ Design by Contract (não peça demais, não prometa menos)

The term IS-A is too broad to act as a definition of a subtype.The true definition of a subtype is substitutable ...

(Robert Martin)


Interface SegregationMuitas Interfaces específicas são melhores do que

uma Inferface de proposito geral




AtmUI+ requestDeposit+ requestWithdrawl+ requestTransfer+ informeInsufficientFunds

Interface Segregation S.O.L.I.D

Conclusão❖ Evita a utilização de “Fat Classes”

❖ Quebra a dependência de métodos que não são invocados pelos clientes

❖ Permite a independência entre clientes


Interface Segregation S.O.L.I.D

?Mudança , Dependência , Acoplamento , Ágil , Composição , Interface

Dúvidas

S ingle responsibility

Open/closed

L iskov substitution

I nterface segregation

Dependency inversion


Robert Martin

SOLID


Robert Martin

Agile Software Development, Principles, Patterns, and Practices (Robert Martin - 2002)Agile Principles, Patterns, and Practices in C# (Robert Martin - 2006) SOLID e Design Patterns

The Pragmatic Programmer (Andrew Hunt and Devid Thomas - 1999)Coesão, Acoplamento, Ortogonalidade, Design por Contrato, Lei de Deméter

Clean Code: A Handbook of Agile Software Craftsmanship (Robert C. Martin - 2008)Lei de Deméter, Data Transfer Objects, TDD

Domain-Driven Design: Tackling Complexity in the Heart of Software (Erich Evans - 2003)

Design Patterns: Elements of Reusable Object-Oriented Software (Gang of Four - 1994)Patterns of Enterprise Applications Architecture (PoeAA: Martin Fowler - 2002)

Apps para Android


Livros Recomendados

VALEU !!!Mario Rezende

http://about.me/mariorez



solid: bom design em orientação a objetos

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