新增 策略模式 Strategy Pattern

Kantai235 · Kantai235 · commit 7c69b1bf0e6b · 2020-10-08T17:50:27.000+08:00
diff --git a/DesignPatterns/Behavioral/README.md b/DesignPatterns/Behavioral/README.md
@@ -28,7 +28,7 @@
 狀態模式，讓物件的狀態改變時，一同改變物件的行為模式，就像是大頭菜(Turnips)這個物件，有沒有壞掉只是一個狀態(State)來辨別，但如果壞掉了，那麼會因為狀態改變的關係，而讓大頭菜計算鈴錢價格的方式也跟著改變。
 
 ## [策略模式 Strategy Pattern](/DesignPatterns/Behavioral/StrategyPattern)
-
+策略模式，可以讓物件在運作時更改其行為或算法，你可以透過切換策略物件來改變計有的功能，你需要實作一個介面來代表這個策略物件，然後在主要類別當中去引入這個策略物件，在需要變更時來切換策略物件，來達成不同狀況下所需要的功能，就像是大頭菜的鈴錢有兩種模式，一種是原本的鈴錢，另一種則是過期後歸零，這個鈴錢運算的模式就可以抽離出來作為策略物件。
 
 ## [模板方法 Template Method](/DesignPatterns/Behavioral/TemplateMethod)
 
diff --git a/DesignPatterns/Behavioral/StrategyPattern/README.md b/DesignPatterns/Behavioral/StrategyPattern/README.md
@@ -1,15 +1,147 @@
 ![Banner](https://raw.githubusercontent.com/Kantai235/php-design-pattern/master/DesignPatterns/Behavioral/StrategyPattern/Banner.png)
 
 # 策略模式 Strategy Pattern
+策略模式，可以讓物件在運作時更改其行為或算法，你可以透過切換策略物件來改變計有的功能，你需要實作一個介面來代表這個策略物件，然後在主要類別當中去引入這個策略物件，在需要變更時來切換策略物件，來達成不同狀況下所需要的功能，就像是大頭菜的鈴錢有兩種模式，一種是原本的鈴錢，另一種則是過期後歸零，這個鈴錢運算的模式就可以抽離出來作為策略物件。
 
 ## UML
 ![UML](https://raw.githubusercontent.com/Kantai235/php-design-pattern/master/DesignPatterns/Behavioral/StrategyPattern/UML.png)
 
 ## 實作
+首先我們要定義策略的介面，這個介面我們會希望策略物件必須要實作鈴錢運算(calculatePrice)的方法。
 
+Strategy.php
+```php
+/**
+ * Interface Strategy.
+ */
+interface Strategy
+{
+    /**
+     * @return int
+     */
+    public function calculatePrice(int $price, int $count): int;
+}
+```
+
+再來要實踐大頭菜的策略模式，首先是正常狀況下的大頭菜，會直接拿鈴錢價格、總數相成後即是鈴錢總價，並且將其回傳。
+
+TurnipsStrategy.php
+```php
+/**
+ * Class TurnipsStrategy.
+ */
+class TurnipsStrategy implements Strategy
+{
+    /**
+     * @return int
+     */
+    public function calculatePrice(int $price, int $count): int
+    {
+        return $price * $count;
+    }
+}
+```
+
+至於壞掉的部分，只要大頭菜壞掉就是賣不出去，所以不用進行任何運算，直接回傳 0 鈴錢即可。
+
+SpoliedStrategy.php
+```php
+/**
+ * Class SpoliedStrategy.
+ */
+class SpoliedStrategy implements Strategy
+{
+    /**
+     * @return int
+     */
+    public function calculatePrice(int $price, int $count): int
+    {
+        return 0;
+    }
+}
+```
+
+最後實作大頭菜物件，我們需要順便把策略物件丟進去，如果在建立大頭菜物件時沒有指定策略物件，那麼預設就給予正常的策略物件，並且提供一個可以臨時切換策略物件的方法，以及計算鈴錢總價的方法，這個計算的方法是透過呼叫策略物件的方法來實踐。
+
+Turnips.php
+```php
+/**
+ * Class Turnips.
+ */
+class Turnips
+{
+    /**
+     * @var int
+     */
+    protected int $price;
+
+    /**
+     * @var int
+     */
+    protected int $count;
+
+    /**
+     * @var Strategy
+     */
+    protected Strategy $strategy;
+
+    /**
+     * Turnips constructor.
+     * 
+     * @param int $price
+     * @param int $count
+     * @param Strategy $strategy
+     */
+    public function __construct(int $price, int $count, Strategy $strategy = null)
+    {
+        $this->price = $price;
+        $this->count = $count;
+
+        // 如果在建立大頭菜物件時沒有指定策略物件，那麼預設就給予正常的策略物件。
+        $this->strategy = empty($strategy) ? new TurnipsStrategy() : $strategy;
+    }
+
+    /**
+     * @param Strategy $strategy
+     */
+    public function setStrategy(Strategy $strategy)
+    {
+        $this->strategy = $strategy;
+    }
+
+    /**
+     * @return int
+     */
+    public function calculatePrice(): int
+    {
+        return $this->strategy->calculatePrice($this->price, $this->count);
+    }
+}
+```
 
 ## 測試
+最後我們要測試策略大頭菜是否如預期的可以運行，我們接下來有一項測試分別是建立大頭菜物件，並且給予預設正常的策略物件，正常情況下可以計算出鈴錢，這時候把策略物件替換為壞掉的模式，再重複呼叫方法時，則是獲得 0 鈴錢。
 
+StrategyPatternTest.php
+```php
+/**
+ * Class StrategyPatternTest.
+ */
+class StrategyPatternTest extends TestCase
+{
+    /**
+     * @test
+     */
+    public function test_strategy()
+    {
+        $turnips = new Turnips(100, 40, new TurnipsStrategy);
+        $this->assertEquals(4000, $turnips->calculatePrice());
+
+        $turnips->setStrategy(new SpoliedStrategy());
+        $this->assertEquals(0, $turnips->calculatePrice());
+    }
+}
+```
 
 最後測試的執行結果會獲得如下：
 
@@ -20,6 +152,16 @@ PHPUnit Pretty Result Printer 0.28.0 by Codedungeon and contributors.
 PHPUnit 9.2.6 by Sebastian Bergmann and contributors.
 
 
+ ==> ...fResponsibilitiesTest   ✔  ✔  ✔  
+ ==> CommandPatternTest         ✔  
+ ==> IteratorPatternTest        ✔  ✔  ✔  ✔  
+ ==> MediatorPatternTest        ✔  ✔  ✔  
+ ==> MementoPatternTest         ✔  
+ ==> NullObjectPatternTest      ✔  ✔  ✔  ✔  
+ ==> ObserverPatternTest        ✔  
+ ==> SpecificationPatternTest   ✔  ✔  ✔  ✔  
+ ==> StatePatternTest           ✔  
+ ==> StrategyPatternTest        ✔  
  ==> AbstractFactoryTest        ✔  ✔  ✔  ✔  
  ==> BuilderPatternTest         ✔  ✔  ✔  ✔  
  ==> FactoryMethodTest          ✔  ✔  ✔  ✔  
@@ -40,9 +182,9 @@ PHPUnit 9.2.6 by Sebastian Bergmann and contributors.
  ==> ProxyPatternTest           ✔  ✔  
  ==> RegistryPatternTest        ✔  ✔  ✔  ✔  ✔  
 
-Time: 00:00.037, Memory: 6.00 MB
+Time: 00:00.084, Memory: 8.00 MB
 
-OK (51 tests, 116 assertions)
+OK (74 tests, 147 assertions)
 ```
 
 ## 完整程式碼
diff --git a/DesignPatterns/Behavioral/StrategyPattern/SpoiledStrategy.php b/DesignPatterns/Behavioral/StrategyPattern/SpoiledStrategy.php
@@ -0,0 +1,17 @@
+<?php
+
+namespace DesignPatterns\Behavioral\StrategyPattern;
+
+/**
+ * Class SpoliedStrategy.
+ */
+class SpoliedStrategy implements Strategy
+{
+    /**
+     * @return int
+     */
+    public function calculatePrice(int $price, int $count): int
+    {
+        return 0;
+    }
+}
diff --git a/DesignPatterns/Behavioral/StrategyPattern/Strategy.php b/DesignPatterns/Behavioral/StrategyPattern/Strategy.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace DesignPatterns\Behavioral\StrategyPattern;
+
+/**
+ * Interface Strategy.
+ */
+interface Strategy
+{
+    /**
+     * @return int
+     */
+    public function calculatePrice(int $price, int $count): int;
+}
diff --git a/DesignPatterns/Behavioral/StrategyPattern/Turnips.php b/DesignPatterns/Behavioral/StrategyPattern/Turnips.php
@@ -0,0 +1,54 @@
+<?php
+
+namespace DesignPatterns\Behavioral\StrategyPattern;
+
+/**
+ * Class Turnips.
+ */
+class Turnips
+{
+    /**
+     * @var int
+     */
+    protected int $price;
+
+    /**
+     * @var int
+     */
+    protected int $count;
+
+    /**
+     * @var Strategy
+     */
+    protected Strategy $strategy;
+
+    /**
+     * Turnips constructor.
+     * 
+     * @param int $price
+     * @param int $count
+     * @param Strategy $strategy
+     */
+    public function __construct(int $price, int $count, Strategy $strategy = null)
+    {
+        $this->price = $price;
+        $this->count = $count;
+        $this->strategy = empty($strategy) ? new TurnipsStrategy() : $strategy;
+    }
+
+    /**
+     * @param Strategy $strategy
+     */
+    public function setStrategy(Strategy $strategy)
+    {
+        $this->strategy = $strategy;
+    }
+
+    /**
+     * @return int
+     */
+    public function calculatePrice(): int
+    {
+        return $this->strategy->calculatePrice($this->price, $this->count);
+    }
+}
diff --git a/DesignPatterns/Behavioral/StrategyPattern/TurnipsStrategy.php b/DesignPatterns/Behavioral/StrategyPattern/TurnipsStrategy.php
@@ -0,0 +1,17 @@
+<?php
+
+namespace DesignPatterns\Behavioral\StrategyPattern;
+
+/**
+ * Class TurnipsStrategy.
+ */
+class TurnipsStrategy implements Strategy
+{
+    /**
+     * @return int
+     */
+    public function calculatePrice(int $price, int $count): int
+    {
+        return $price * $count;
+    }
+}
diff --git a/DesignPatterns/Behavioral/StrategyPattern/UML.png b/DesignPatterns/Behavioral/StrategyPattern/UML.png
diff --git a/Tests/Behavioral/StrategyPatternTest.php b/Tests/Behavioral/StrategyPatternTest.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace Tests\Behavioral;
+
+use DesignPatterns\Behavioral\StrategyPattern\SpoliedStrategy;
+use DesignPatterns\Behavioral\StrategyPattern\Turnips;
+use DesignPatterns\Behavioral\StrategyPattern\TurnipsStrategy;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Class StrategyPatternTest.
+ */
+class StrategyPatternTest extends TestCase
+{
+    /**
+     * @test
+     */
+    public function test_strategy()
+    {
+        $turnips = new Turnips(100, 40, new TurnipsStrategy);
+        $this->assertEquals(4000, $turnips->calculatePrice());
+
+        $turnips->setStrategy(new SpoliedStrategy());
+        $this->assertEquals(0, $turnips->calculatePrice());
+    }
+}
diff --git a/UML.mdj b/UML.mdj
