[Unity] Create MenuItems dynamically to add/remove preprocessor macros.

CustomDefines.cs

using UnityEngine;
using UnityEditor;
using System.Text;

namespace MyUtil
{
    [InitializeOnLoad]
    public partial class CustomDefines
    {  
        private const string ScriptPath = "/Util/Editor/MyDefines.cs";  //path including the name of to the (to be) generated File
        private const string MENU = "CustomDefines/";                 //name of the menu tab where all menuitems will be accessed
   
        private static readonly string[] DEFINES = {                 //all custom global defines come here
            "DEBUG_LOG",
            "ENABLE_ANALYTICS",
            "RUN_TESTS",
            "USE_MOCKUP_SERVER"
        };

        static CustomDefines() {
            GenerateItems(); 

            //Wait for Unity to be ready
            EditorApplication.delayCall += () => {
               UpdateCheckedAll();
            };
        }
        public static void GenerateItems()
        {
            string filePath = Application.dataPath + ScriptPath;
            StringBuilder builder = new StringBuilder();
            builder.AppendLine("/******************");
            builder.AppendLine("*  AUTO GENERATED  *");
            builder.AppendLine("/*******************/");
            builder.AppendLine("");
            builder.AppendLine("using UnityEngine;");
            builder.AppendLine("using UnityEditor;");
            builder.AppendLine("\nnamespace MyUtil");
            builder.AppendLine("{");
            builder.AppendLine("\tpublic partial class CustomDefines");
            builder.AppendLine("\t{");
   
            string updateCheckedAllMethod = "\t\tstatic partial void UpdateCheckedAll() {";   //Update marker AFTER the generated file was imported by Unity
            for(int i = 0; i<DEFINES.Length; ++i) { 
                builder.AppendLine("\t\t[MenuItem(\""+ MENU + DEFINES[i] +"\")]");
                builder.AppendLine("\t\tpublic static void Toggle"+ DEFINES[i] +"() { ");
                builder.AppendLine("\t\t\tToggleDefine(\""+DEFINES[i]+"\");");
                builder.AppendLine("\t\t}\n");
                updateCheckedAllMethod += "\n\t\t\tUpdateChecked(\""+ DEFINES[i] +"\");";
            }
            
            updateCheckedAllMethod += "\n\t\t}\n";
            builder.Append(updateCheckedAllMethod);
            builder.AppendLine("\t}");
            builder.AppendLine("}");
               
            System.IO.File.WriteAllText(filePath, builder.ToString());
            AssetDatabase.Refresh();
        }

        public static void ToggleDefine(string define) {
            // ";" added as pre- and postfix to not care about about substrings in defines. 
            string symbols = ";"+PlayerSettings.GetScriptingDefineSymbolsForGroup(BuildTargetGroup.Standalone)+";";
            if (!symbols.Contains(";"+define+";")) {
                PlayerSettings.SetScriptingDefineSymbolsForGroup(BuildTargetGroup.Standalone, symbols + define);
                Menu.SetChecked(MENU+define, true);
            }
            else {
                symbols = symbols.Replace(";"+define+";", ";");
                PlayerSettings.SetScriptingDefineSymbolsForGroup(BuildTargetGroup.Standalone, symbols);
                Menu.SetChecked(MENU+define, false);
            }
        }
        
        static partial void UpdateCheckedAll();

        public static void UpdateChecked(string define) {
            string symbols = PlayerSettings.GetScriptingDefineSymbolsForGroup(BuildTargetGroup.Standalone);
            Menu.SetChecked(MENU+define, symbols.Contains(define));
        }
         
    }
}