EditorPlayBootstrapper

This script EditorPlayBootstrapper.cs is an editor-only utility in Unity that automates how your game enters Play Mode in the Editor, especially useful for bootloader patterns like yours (with PersistentManagers as the entry point). Here’s a detailed breakdown:

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🔹 File Location & Purpose

• Path: Assets/-----Game-----/Scripts/Editor/EditorPlayBootstrapper.cs

• Purpose: Ensures that whenever you press Play in the Unity Editor, the game starts from your boot scene (PersistentManagers), no matter what scene you were editing before.

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🔸 Key Concepts in This Script

1.

[InitializeOnLoad]

• This attribute tells Unity:

  “Run this class’s static constructor automatically whenever the editor loads.”

So even before you press Play, this script hooks into Unity’s lifecycle.

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2.

EditorApplication.playModeStateChanged += OnPlayModeChanged;

• Inside the static constructor:

static EditorPlayBootstrapper()
{
    EditorApplication.playModeStateChanged += OnPlayModeChanged;
}

This line registers a listener for Play Mode state changes (e.g., Entering Play Mode, Exiting, etc.).

When such a state change occurs, it runs:

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🔹 OnPlayModeChanged: How It Works

private static void OnPlayModeChanged(PlayModeStateChange state)

This method is the heart of the script.

✅ When you press Play in the editor:

if (state == PlayModeStateChange.EnteredPlayMode)

• Step 1:

  Store your currently open scene so that you can come back to it later:

previousScenePath = SceneManager.GetActiveScene().path;

• Step 2:

  Load your bootloader entry scene:

SceneManager.LoadScene(BootScenePath, LoadSceneMode.Single);

• This replaces your current scene with PersistentManagers.

  • This ensures your game always starts the same way, like in a real build.

• Optional:

//SceneManager.LoadScene(MainScenePath, LoadSceneMode.Additive);

• If uncommented, this would also load MainMenu additively, useful if you want to test from the main menu directly.

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🔁 When you stop playing (back to Edit Mode):

else if (state == PlayModeStateChange.EnteredEditMode)

• It restores the scene you were working on before pressing Play:

EditorSceneManager.OpenScene(previousScenePath, OpenSceneMode.Single);

So you don’t lose your editing context — you go back to where you left off.

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📌 Summary – What It Automates

Action	What Happens
You hit ▶ Play	Unity switches to PersistentManagers scene automatically
You stop Play	Unity goes back to your last edited scene
Bootload pattern support	Ensures correct loading order in Editor like in real game
Benefit	No need to manually switch to PersistentManagers every time you test

✅ Tips for You

1. Make sure PersistentManagers is marked to DontDestroyOnLoad for managers.

2. This script only affects the Editor, not the actual build.

why use "initializeOnLoad and static constructor

1. ✅ Why [InitializeOnLoad] is used

2. ✅ Why the class and constructor are static

✅ 1. What does [InitializeOnLoad] do?

In Unity Editor scripts, [InitializeOnLoad] makes Unity run the static constructor as soon as the Unity Editor finishes loading, or after domain reload (e.g., script recompile, reentering Play Mode). This is Editor-only behavior and only works in classes inside an Editor folder or marked with #if UNITY_EDITOR.

✅ 2. Why static class and static constructor?

🔹

static class EditorPlayBootstrapper

• A static class:

  • Cannot be instantiated (no new allowed)

  • Can only contain static members

  • Best for utility/helper code

  • Keeps things self-contained and memory-efficient

static EditorPlayBootstrapper()

This is a C# static constructor. Key facts:

• Automatically runs once when the class is accessed for the first time — OR immediately on load when combined with [InitializeOnLoad]

• No parameters allowed

• You can’t call it manually; it’s guaranteed to run once

Why it’s perfect here: You want to hook into:

EditorApplication.playModeStateChanged += OnPlayModeChanged;

…exactly once, when the Editor loads. This ensures Unity watches for Play mode changes from the start.

✅ 3. What C# rules and concepts are involved?

Concept	Description
static class	Cannot be instantiated; used for utility or singleton-like behavior
static constructor	Auto-executes once per domain load; no args; cannot be manually called
delegate	playModeStateChanged uses a delegate event to register callbacks
+=	Adds a method to an event handler list