Domain Reload support w/ Source Generator

Source Generator to support Domain Reload off in Unity (handle static fields and event handlers).

Installation

You can choose manually installing the package or from GitHub source.

Manual install

Download the latest release from here.
Extract the DLL file somewhere into your Assets folder.
Continue below at the "Finishing" section

Build from source

Clone the repo
Open up in your favorite IDE
Build the solution
Copy the <repo path>\bin\Release\netstandard2.0\DomainReloadSupport.dll somewhere into your Assets folder

Finishing

Follow the instructions here:

Inside the Asset Browser, click on the .dll file to open the Plugin Inspector window.

Go to Select platforms for plugin and disable Any Platform.

Go to Include Platforms and disable Editor and Standalone.

Go to Asset Labels and open the Asset Labels sub-menu.

Create and assign a new label called RoslynAnalyzer. To do this, enter “RoslynAnalyzer” into the text input window in the Asset Labels sub-menu. This label must match exactly and is case sensitive. After you create the label for the first analyzer, The label appears in the Asset Labels sub-menu. You can click on the name of the label in the menu to assign it to other analyzers.

Limitations

The class you're augmenting has to be decorated with the partial keyword.
Currently there is no way of excluding static fields or methods from this service.

Exclusion

Decorate your partial class with [NoDomainReloadSupport] attribute if you want to exclude it completely.

Example

using LurkingNinja.FirstNameSpace.SecondNameSpace.ForTest;
using UnityEngine;

public partial class TestStaticOnNoDomainReload : MonoBehaviour
{
    private static int _number;
    
    private void Start()
    {
        Debug.Log($"Started with {_number}");
        _number += 10;
        Application.quitting += OnQuit;
        OtherTestEvent.OnChangeSomethingStatic += OnQuit;
        Debug.Log($"Ended with {_number}");
    }

    private static void OnQuit() => Debug.Log("Exiting");
}

The result after entering play mode twice:

Obviously the Edit > Project Settings > Editor > Enter Play Mode is set and the Reload Domain is not set.

The generated source code: TestStaticOnNoDomainReload_codegen.cs

using LurkingNinja.FirstNameSpace.SecondNameSpace.ForTest;
using UnityEngine;
using System;

    public partial class TestStaticOnNoDomainReload 
    {
#if UNITY_EDITOR
        [UnityEditor.InitializeOnEnterPlayMode]
        static void ApplyStaticFieldsAndEventHandlers(UnityEditor.EnterPlayModeOptions options)
        {
            if (!options.HasFlag(UnityEditor.EnterPlayModeOptions.DisableDomainReload)) return;
			_number = default;
			Application.quitting -= OnQuit;
			OtherTestEvent.OnChangeSomethingStatic -= OnQuit;

        }
#endif
    }

Changelog

[0.0.5] - 2024-01-12

Changed

Moved into a real Unity project
Unity Test added to detect if static variable resets upon entering play mode while the Domain Reload is off

Previous changes >

LurkingNinja/DomainReloadSG