[PHP] [StepStrategy] Define typed code constants as a first step towards polymorphism

Author: JavierCane

examples/php/php-step_strategy-02_replace_type_code_with_strategy/src/Step.php

@@ -9,8 +9,12 @@ final class Step
     private const EXERCISE_STEP_DURATION_ESTIMATION_IN_MINUTES = 30;
     private const QUIZ_STEP_QUESTION_DURATION_ESTIMATION_IN_MINUTES = 3;
 
+    private const VIDEO_STEP_TYPE = 0;
+    private const QUIZ_STEP_TYPE = 1;
+    private const EXERCISE_STEP_TYPE = 2;
+
     private string $title;
-    private int    $type; // 0: Video, 1: Quizz, 2: Exercise
+    private int    $type;
     private ?int    $videoDurationInMinutes;
     private ?array  $quizQuestions;
 
@@ -26,11 +30,11 @@ public function estimatedCompletionMinutes(): int
     {
         $estimation = 0;
 
-        if ($this->type === 0) { // Video
+        if ($this->type === self::VIDEO_STEP_TYPE) {
             $estimation = $this->videoDurationInMinutes;
-        } elseif ($this->type === 1) { // Quizz
+        } elseif ($this->type === self::QUIZ_STEP_TYPE) {
             $estimation = self::QUIZ_STEP_QUESTION_DURATION_ESTIMATION_IN_MINUTES * count($this->quizQuestions);
-        } elseif ($this->type === 2) { // Exercise
+        } elseif ($this->type === self::EXERCISE_STEP_TYPE) {
             $estimation = self::EXERCISE_STEP_DURATION_ESTIMATION_IN_MINUTES;
         }