Design Patterns in 30 Minutes.
HELLO!
I am Win Yu.
kylinwin
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Outline
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Design Patterns
Creational
Structal
Behavioral
Design Patterns
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💁♂️ Design patterns are solutions to recurring problems; guidelines on how to tackle certain problems.
💣 Design patterns are not a silver bullet to all your problems.
KISS
Keep It Simple Stupid.
DRY
Don’t Repeat Yourself.
Maintainable
Design Patterns
Common Types
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Creational
Behavioral
Structural
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Creational
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Creational patterns are focused towards how to instantiate an object or group of related objects.
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— Class instantiation
— Hiding the creation logic
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Builder(Manager) Pattern
Allows you to create different flavors of an object while avoiding constructor pollution.
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Wikipedia says
The builder pattern is an object creation software design pattern with the intentions of finding a solution to the telescoping constructor anti-pattern.
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Builder 模式一步一步建立實體物件的部分組成，最後再回傳一個完整的物件
Telescoping constructor anti-pattern
public function __construct($size, $cheese = true, $pepperoni = true, $tomato = false, $lettuce = true)�{�}
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We have a burger.
class Burger�{� protected $size;�� protected $cheese = false;� protected $pepperoni = false;� protected $lettuce = false;� protected $tomato = false;�� public function __construct(BurgerBuilder $builder)� {� $this->size = $builder->size;� $this->cheese = $builder->cheese;� $this->pepperoni = $builder->pepperoni;� $this->lettuce = $builder->lettuce;� $this->tomato = $builder->tomato;� }�}
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We have the builder.
class BurgerBuilder�{� public $size;�� public $cheese = false;� public $pepperoni = false;� public $lettuce = false;� public $tomato = false;�� public function __construct(int $size)� {� $this->size = $size;� }�� public function addPepperoni()� {� $this->pepperoni = true;� return $this;� }� public function addLettuce()� {� $this->lettuce = true;� return $this;� }� ...
public function addCheese()� {� $this->cheese = true;� return $this;� }�� public function addTomato()� {� $this->tomato = true;� return $this;� }�� public function build(): Burger� {� return new Burger($this);� }�}
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Create burger via builder.
$burger = (new BurgerBuilder(14))� ->addPepperoni()� ->addLettuce()� ->addTomato()� ->build();
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Laravel Manager Pattern Examples
Illuminate\Auth\AuthManager
Illuminate\Broadcasting\BroadcastManager
Illuminate\Cache\CacheManager
Illuminate\Filesystem\FilesystemManager
Illuminate\Mail\TransportManager
Illuminate\Notifications\ChannelManager
Illuminate\Queue\QueueManager
Illuminate\Session\SessionManager
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Singleton Pattern
Ensures that only one object of a particular class is ever created.
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確保類別只有一個實例(instance)，
並提供所有使用對象該實例的方法
To create a singleton, make the constructor private, disable cloning, disable extension and create a static variable to house the instance
final class President�{� private static $instance;�� private function __construct()� {� // Hide the constructor� }�� public static function getInstance(): President� {� if (!self::$instance) {� self::$instance = new self();� }�� return self::$instance;� }�� private function __clone()� {� // Disable cloning� }�� private function __wakeup()� {� // Disable unserialize� }�}
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Verify
$president1 = President::getInstance();�$president2 = President::getInstance();��var_dump($president1 === $president2); // true
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Singleton in Service Container
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https://blog.albert-chen.com
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Structural
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Structural patterns are mostly concerned with object composition or in other words how the entities can use each other.
> "How to build a software component?"
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— Composition between objects
— Usages of interfaces, abstract classes
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Composite Pattern
Composite pattern lets clients treat the individual objects in a uniform manner.
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組合模式可以表示單一物件和群體階層的關係。
群體為這單一物件的相同型別集合，
他們有著相同的行為
Different employee types
interface Employee�{� public function __construct(string $name, float $salary);� public function getName(): string;� public function setSalary(float $salary);� public function getSalary(): float;�}
class Developer implements Employee�{� protected $salary;� protected $name;� � public function __construct(string $name, float $salary)� {� $this->name = $name;� $this->salary = $salary;� }�� public function getName(): string� {� return $this->name;� }�� public function setSalary(float $salary)� {� $this->salary = $salary;� }�� public function getSalary(): float� {� return $this->salary;� }�}�
class Designer implements Employee�{� protected $salary;� protected $name;� � public function __construct(string $name, float $salary)� {� $this->name = $name;� $this->salary = $salary;� }�� public function getName(): string� {� return $this->name;� }�� public function setSalary(float $salary)� {� $this->salary = $salary;� }�� public function getSalary(): float� {� return $this->salary;� }�}�
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The organization which consists of several different types of employees
// Prepare the employees�$john = new Developer('John Doe', 12000);�$jane = new Designer('Jane Doe', 15000);��// Add them to organization�$organization = new Organization();�$organization->addEmployee($john);�$organization->addEmployee($jane);��echo "Net salaries: " . $organization->getNetSalaries();
// Net Salaries: 27000
class Organization�{� protected $employees;�� public function addEmployee(Employee $employee)� {� $this->employees[] = $employee;� }�� public function getNetSalaries(): float� {� $netSalary = 0;�� foreach ($this->employees as $employee) {� $netSalary += $employee->getSalary();� }�� return $netSalary;� }�}
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Facade Pattern
Facade pattern provides a simplified interface to a complex subsystem.
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封裝商業邏輯並提供簡單介面，以達到
易使用、可讀性提高、減少依賴的目的
We have the computer class.
class Computer�{� public function getElectricShock()� {� echo "Ouch!";� }�� public function makeSound()� {� echo "Beep beep!";� }�� public function showLoadingScreen()� {� echo "Loading..";� }�� public function bam()� {� echo "Ready to be used!";� }��
public function closeEverything()� {� echo "Bup bup bup buzzzz!";� }�� public function sooth()� {� echo "Zzzzz";� }�� public function pullCurrent()� {� echo "Haaah!";� }�}
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We have the Facade
class ComputerFacade�{� protected $computer;�� public function __construct(Computer $computer)� {� $this->computer = $computer;� }�� public function turnOn()� {� $this->computer->getElectricShock();� $this->computer->makeSound();� $this->computer->showLoadingScreen();� $this->computer->bam();� }�� public function turnOff()� {� $this->computer->closeEverything();� $this->computer->pullCurrent();� $this->computer->sooth();� }�}
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Now to use the facade
$computer = new ComputerFacade(new Computer());�$computer->turnOn(); // Ouch! Beep beep! Loading.. Ready to be used!�$computer->turnOff(); // Bup bup buzzz! Haah! Zzzzz
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Laravel Facade Pattern Examples
Illuminate\Support\Facades\Facade.php
Illuminate\Support\Facades\App.php
Illuminate\Support\Facades\Blade.php
Illuminate\Support\Facades\Cache.php
Illuminate\Support\Facades\DB.php
Illuminate\Support\Facades\File.php
Illuminate\Support\Facades\Queue.php
Illuminate\Support\Facades\Response.php
…...
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Facades in Laravel
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3.
Behavioral
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It is concerned with assignment of responsibilities between the objects.
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— Communication between objects
— Usages of mostly interfaces
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Structural pattern vs. Behavioral pattern
The Behavioral patterns don't just specify the structure but also outline the patterns for message passing/communication between them.
In other words, they assist in answering :
"How to run a behavior in software component?"
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Strategy Pattern
Strategy pattern allows you to switch the algorithm or strategy based upon the situation.
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定義多個演算法，各別封裝這些演算法，
並讓它們可以互換
interface SortStrategy�{� public function sort(array $dataset): array;�}��class BubbleSortStrategy implements SortStrategy�{� public function sort(array $dataset): array� {� echo "Sorting using bubble sort";�� // Do sorting� return $dataset;� }�}��class QuickSortStrategy implements SortStrategy�{� public function sort(array $dataset): array� {� echo "Sorting using quick sort";�� // Do sorting� return $dataset;� }�}
class Sorter�{� protected $sorter;�� public function __construct(SortStrategy $sorter)� {� $this->sorter = $sorter;� }�� public function sort(array $dataset): array� {� return $this->sorter->sort($dataset);� }�}
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Decide your strategy via Sorter
$dataset = [1, 5, 4, 3, 2, 8];��$sorter = new Sorter(new BubbleSortStrategy());�$sorter->sort($dataset); // Output : Sorting using bubble sort��$sorter = new Sorter(new QuickSortStrategy());�$sorter->sort($dataset); // Output : Sorting using quick sort
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Template Pattern
Template method defines the skeleton of how a certain algorithm could be performed, but defers the implementation of those steps to the children classes.
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定義一個包含方法和執行流程的抽象樣板，
讓實作類別透過繼承的方式實作方法的細節。
最後透過樣板已經定義好的流程執行
Define abstract class
abstract class Builder�{�� // Template method� final public function build()� {� $this->test();� $this->lint();� $this->assemble();� $this->deploy();� }�� abstract public function test();� abstract public function lint();� abstract public function assemble();� abstract public function deploy();�}
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class AndroidBuilder extends Builder�{� public function test()� {� echo 'Running android tests';� }�� public function lint()� {� echo 'Linting the android code';� }�� public function assemble()� {� echo 'Assembling the android build';� }�� public function deploy()� {� echo 'Deploying android build to server';� }�}
class IosBuilder extends Builder�{� public function test()� {� echo 'Running ios tests';� }�� public function lint()� {� echo 'Linting the ios code';� }�� public function assemble()� {� echo 'Assembling the ios build';� }�� public function deploy()� {� echo 'Deploying ios build to server';� }�}
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Use your strategy for different scenarios.
$androidBuilder = new AndroidBuilder();�$androidBuilder->build();��// Output:�// Running android tests�// Linting the android code�// Assembling the android build�// Deploying android build to server��$iosBuilder = new IosBuilder();�$iosBuilder->build();��// Output:�// Running ios tests�// Linting the ios code�// Assembling the ios build�// Deploying ios build to server
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See more in my references
https://github.com/kamranahmedse/design-patterns-for-humans#-command
https://github.com/domnikl/DesignPatternsPHP
https://www.slideshare.net/BobbyBouwmann/laravel-design-patterns-86729254
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THANKS!
Any questions?
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