C# TypeBuilder 动态生成具有函数的类

Question

我正在尝试使用 C# 中的 TypeBuilder 动态生成具有函数的类，并让该函数调用另一个基函数。

之所以需要这样做，是因为在 Revit 应用程序开发中，每个按钮都需要有一个类，该类使用 Execute 函数实现 IExternalCommand。我想动态创建按钮并在运行时根据它们的 ID 处理它们的执行，因此我也需要动态创建类。

希望这段代码能找到我正在寻找的东西（或这里http://pastebin.com/eehGKteT）：

using Autodesk.Revit.DB;
using Autodesk.Revit.UI;

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Reflection;
using System.Reflection.Emit;

namespace Centek_Revit_Addin
{
    class DynamicButton
    {
        // I would like to use a function like this to generate the class during runtime, presumably using TypeBuilder:
        public static void generateClass(int id)
        {
            // ... Code which would generate a class with the name "GeneratedClass" with the 'id' parameter appended at the end
            // ... The class implements IExternalCommand
            // ... The class has an Execute function with the parameters listed in the example, which returns a call to the Execute function in DynamicButton
            //      along with the added integer 'id' parameter at the end
        }

        public static Autodesk.Revit.UI.Result Execute(ExternalCommandData revit, ref string message, ElementSet elements, int id)
        {
            TaskDialog.Show("About", "ID of the class that called us: " + id);
            return Autodesk.Revit.UI.Result.Succeeded;
        }
    }


    // ===== This class would have been generated during runtime using generateClass(15) ====== //
    class GeneratedClass15 : Autodesk.Revit.UI.IExternalCommand
    {
        public Autodesk.Revit.UI.Result Execute(Autodesk.Revit.UI.ExternalCommandData revit, ref string message, Autodesk.Revit.DB.ElementSet elements)
        {
            return DynamicButton.Execute(revit, ref message, elements, 15);
        }
    }
    // =================================================================== //
}

我试图让 TypeBuilder 工作，并且我了解了基础知识，但我似乎无法弄清楚如何使用 Opcodes 来获得我想要的类。

所以基本上我正在寻找编写 generateClass(int id) 函数的帮助。任何帮助将不胜感激！

编辑：

I would like to add my progress:
using Autodesk.Revit.DB;
using Autodesk.Revit.UI;

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Reflection;
using System.Reflection.Emit;

namespace Centek_Revit_Addin
{
    class DynamicButton
    {
        // I would like to use a function like this to generate the class during runtime, presumably using TypeBuilder:
        public static void generateClass(int id)
        {
            // ... Code which would generate a class with the name "GeneratedClass" with the 'id' parameter appended at the end
            // ... The class implements IExternalCommand
            // ... The class has an Execute function with the parameters listed in the example, which returns a call to the Execute function in DynamicButton
            //      along with the added integer 'id' parameter at the end

            AssemblyName aName = new AssemblyName("DynamicAssemblyExample");
            AssemblyBuilder ab = AppDomain.CurrentDomain.DefineDynamicAssembly(aName, AssemblyBuilderAccess.RunAndSave);

            // For a single-module assembly, the module name is usually 
            // the assembly name plus an extension.
            ModuleBuilder mb = ab.DefineDynamicModule(aName.Name, aName.Name + ".dll");

            // Create class which extends Object and implements IExternalCommand
            Type[] implements = {typeof(IExternalCommand)};
            TypeBuilder tb = mb.DefineType("GeneratedClass" + id, TypeAttributes.Public, typeof(Object), implements);


            // Create 'Execute' function sig
            Type[] paramList = {typeof(ExternalCommandData), typeof(string), typeof(ElementSet)};
            MethodBuilder mbExecute = tb.DefineMethod("Execute", MethodAttributes.Public, typeof(Result), paramList);

            // Create 'Execute' function body
            ILGenerator ilGen = mbExecute.GetILGenerator();

            ilGen.Emit(OpCodes.Nop);
            ilGen.Emit(OpCodes.Ldarg_1);
            ilGen.Emit(OpCodes.Ldarg_2);
            ilGen.Emit(OpCodes.Ldarg_3);

            ilGen.Emit(OpCodes.Ldc_I4_S, id);

            Type[] paramListWID = { typeof(ExternalCommandData), typeof(string), typeof(ElementSet), typeof(int) };
            ilGen.EmitCall(OpCodes.Call, typeof(DynamicButton).GetMethod("Execute"), paramListWID);


            //ilGen.Emit(OpCodes.Ret);


            tb.CreateType();
        }

        public static Autodesk.Revit.UI.Result Execute(ExternalCommandData revit, ref string message, ElementSet elements, int id)
        {
            TaskDialog.Show("About", "ID of the class that called us: " + id);
            return Autodesk.Revit.UI.Result.Succeeded;
        }
    }



    // ===== This class would have been generated during runtime using generateClass(15) ====== //
    class GeneratedClass15 : Autodesk.Revit.UI.IExternalCommand
    {
        public Autodesk.Revit.UI.Result Execute(Autodesk.Revit.UI.ExternalCommandData revit, ref string message, Autodesk.Revit.DB.ElementSet elements)
        {
            return DynamicButton.Execute(revit, ref message, elements, 15);
        }
    }
    // =================================================================== //
}

这段代码更接近，但运行时出现错误

System.TypeLoadException：“GeneratedClass99”类型中的方法“执行” 从程序集'DynamicAssemblyExample，版本= 0.0.0.0， Culture=neutral, PublicKeyToken=null' 没有实现。

当我在generateClass(..) 中调用CreateType(..) 时出现此错误

Answer 1

首先，您必须修复正在使用的参数类型。注意message参数有ref属性，所以你应该把typeof(String)改成Type.GetType("System.String&")。

您必须声明您的执行方法从接口实现（覆盖）执行方法：

tb.DefineMethodOverride(mbExecute, typeof(IExternalCommand).GetMethod("Execute"));

我使用控制台应用程序进行了一些测试，通过上述更改，我能够使其正常工作：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Reflection;
using System.Reflection.Emit;

namespace ConsoleApplication10
{
    class Program
    {
        static void Main(string[] args)
        {
            int a;
            string s = "";
            while ((a = int.Parse(Console.ReadLine())) != 0)
            {


                var t = DynamicButton.generateClass(a);

                ((IExternalCommand)t.GetConstructor(new Type[0]).Invoke(new object[0])).Execute(null, ref s, null);
            }
        }
    }

    public interface IExternalCommand
    {
        Result Execute(ExternalCommandData revit, ref string message, ElementSet elements);
    }

    public class DynamicButton
    {
        // I would like to use a function like this to generate the class during runtime, presumably using TypeBuilder:
        public static Type generateClass(int id)
        {
            // ... Code which would generate a class with the name "GeneratedClass" with the 'id' parameter appended at the end
            // ... The class implements IExternalCommand
            // ... The class has an Execute function with the parameters listed in the example, which returns a call to the Execute function in DynamicButton
            //      along with the added integer 'id' parameter at the end

            AssemblyName aName = new AssemblyName("DynamicAssemblyExample");
            AssemblyBuilder ab = AppDomain.CurrentDomain.DefineDynamicAssembly(aName, AssemblyBuilderAccess.RunAndSave);

            // For a single-module assembly, the module name is usually 
            // the assembly name plus an extension.
            ModuleBuilder mb = ab.DefineDynamicModule(aName.Name, aName.Name + ".dll");

            // Create class which extends Object and implements IExternalCommand
            var implements = new Type[] {typeof(IExternalCommand)};
            TypeBuilder tb = mb.DefineType("GeneratedClass" + id, TypeAttributes.Public, typeof(Object), implements);


            // Create 'Execute' function sig
            Type[] paramList = {typeof(ExternalCommandData), Type.GetType("System.String&"), typeof(ElementSet)};
            MethodBuilder mbExecute = tb.DefineMethod("Execute", MethodAttributes.Public | MethodAttributes.Virtual, typeof(Result), paramList);

            // Create 'Execute' function body
            ILGenerator ilGen = mbExecute.GetILGenerator();

            ilGen.Emit(OpCodes.Nop);
            ilGen.Emit(OpCodes.Ldarg_1);
            ilGen.Emit(OpCodes.Ldarg_2);
            ilGen.Emit(OpCodes.Ldarg_3);

            ilGen.Emit(OpCodes.Ldc_I4_S, id);

            Type[] paramListWID = { typeof(ExternalCommandData), Type.GetType("System.String&"), typeof(ElementSet), typeof(int) };
            ilGen.EmitCall(OpCodes.Call, typeof(DynamicButton).GetMethod("Execute"), paramListWID);


            ilGen.Emit(OpCodes.Ret);



            tb.DefineMethodOverride(mbExecute, typeof(IExternalCommand).GetMethod("Execute"));
            return tb.CreateType();
        }

        public static Result Execute(ExternalCommandData revit, ref string message, ElementSet elements, int id)
        {
            Console.WriteLine("About {0}", "ID of the class that called us: " + id);
            return Result.Succeeded;
        }
    }

    public enum Result
    {
        Succeeded
    }

    public class ExternalCommandData { }
    public class ElementSet { }
    // =================================================================== //
}