Create and use a source generator

System.Text.Json

6.0.0-preview

System.Text.Json

1. In your IDE, create a C# class library project that targets .NET Standard 2.0 and name the project

   ExampleSourceGenerator

   .
2. Install the

   Microsoft.CodeAnalysis.Csharp

   NuGet package for the project. Your source generator must use Microsoft.CodeAnalysis.Csharp 4.3 to work with Unity.
3. In your IDE project, create a new C# file and add the following code:

   using Microsoft.CodeAnalysis;using Microsoft.CodeAnalysis.Text;using System.Text;namespace ExampleSourceGenerator{    [Generator]    public class ExampleSourceGenerator : ISourceGenerator    {        public void Execute(GeneratorExecutionContext context)        {            System.Console.WriteLine(System.DateTime.Now.ToString());            var sourceBuilder = new StringBuilder(            @"            using System;            namespace ExampleSourceGenerated            {                public static class ExampleSourceGenerated                {                    public static string GetTestText()                    {                        return ""This is from source generator ");            sourceBuilder.Append(System.DateTime.Now.ToString());            sourceBuilder.Append(                @""";                    }    }}");            context.AddSource("exampleSourceGenerator", SourceText.From(sourceBuilder.ToString(), Encoding.UTF8));        }        public void Initialize(GeneratorInitializationContext context) { }    }}

4. Build your source generator with a release build configuration.
5. In your source generator's project folder, find the

   bin/Release/netstandard2.0/ExampleSourceGenerator.dll

   file.
6. Copy this file into your Unity project, inside the

   Assets

   folder.
7. Inside the Asset Browser, click on the .dll file to open the Plugin Inspector window.
8. Under Select platforms for plugin, uncheck Any Platform.
9. Under Include Platforms, uncheck Editor and Standalone and any other checked platforms.
10. Under Asset Labels, click on the label icon to open the Asset labels sub-menu.
11. Create and assign a new label called RoslynAnalyzer. To do this, type

    RoslynAnalyzer

    in the text input field of the Asset labels sub-menu and press enter. This label must match exactly and is case sensitive. Once created, the label appears in the Asset labels sub-menu from then on. You can click on the name of the label in the menu to assign it to other analyzers.
12. To test the source generator is working, create a new MonoBehaviour script in the Editor with the following code:

    using UnityEngine;public class HelloFromSourceGenerator : MonoBehaviour{    static string GetStringFromSourceGenerator()    {        return ExampleSourceGenerated.ExampleSourceGenerated.GetTestText();    }    // Start is called before the first frame update    void Start()    {        var output = "Test";        output = GetStringFromSourceGenerator();        Debug.Log(output);    }}

13. If the source generator is injected into more than one assembly, your IDE displays a compiler warning about conflicts (CS0436). To remove this warning, you can do one of the following:
    • Make the

      ExampleSourceGenerated

      class in the

      ExampleSourceGenerator

      example

      internal

      . Important: in this case you can only access the generated class from within the same assembly.
    • Change the name of the

      ExampleSourceGenerated

      class so that it's unique to a given assembly, for example

      ExampleSourceGenerated_MyAssembly

      .
14. Add this script to a GameObject in the scene and enter Play mode. A message from the source generator appears in the Console window, including the time stamp.

Additional resources

• Install and use an existing analyzer or source generator