如何在C＃EMIT中使用不确定参数创建动态函数

Question

我想在项目中创建动态函数，但是函数参数的数量不确定，也许是两个，也许是三个或更多，然后我想在项目中运行静态函数，静态函数接受某些参数，因此，我该怎么做？最重要的是如何处理参数？

我的动态函数演示

public static void UDFCreate(string name, string type,List<string> paramList, string APIID)
{
            Type[] types = new Type[paramList.Count];
            foreach (string param in paramList)
            {
                int index = paramList.IndexOf(param);
                types[index] = typeof(double);
            }
            
            DynamicMethod mult = new DynamicMethod(name, typeof(double), types, typeof(UDFGenerator));
            ILGenerator il = mult.GetILGenerator();
            il.Emit(OpCodes.Ldarg_0);//
            il.Emit(OpCodes.Ldarg_1);// 
            il.Emit(OpCodes.Add);// 
            il.Emit(OpCodes.Ret);// 
            List<Delegate> delegates = new List<Delegate>();
            delegates.Add(mult.CreateDelegate(typeof(Func<double, double, double>)));
            // 
            ExcelFunctionAttribute att = new ExcelFunctionAttribute();
            att.Name = name;
            att.Description = "A function to multiply two numbers";
    
            List<object> funcAttribs = new List<object>();
            funcAttribs.Add(att);
            // 
            ExcelArgumentAttribute atta1 = new ExcelArgumentAttribute();
            atta1.Description = "is the first number";
    
            ExcelArgumentAttribute atta2 = new ExcelArgumentAttribute();
            atta2.Description = "is the second number";
            List<object> argAttribs = new List<object>();
            argAttribs.Add(atta1);
            argAttribs.Add(atta2);
    
            List<List<object>> argAttribsList = new List<List<object>>();
            argAttribsList.Add(argAttribs);
            try
            {
                // 
                ExcelIntegration.RegisterDelegates(delegates, funcAttribs, argAttribsList);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

我的静态函数结构，只有 paramlist 需要在运行时创建，其他人可以

private static async void GetApiResult(string id, string type, List<string> paramNameList, params string[] paramList)

---

在两天后 通过 udfcreate 获得 非常感谢@jeremylakeman，非常有帮助

private static void EmitTwo(ILGenerator il, string type, List<string> paramList, string APIID)
        {
            // Stores the APIID in a local variable with index 0
            il.Emit(OpCodes.Ldarg_0); // this line is must
            il.Emit(OpCodes.Ldfld, APIID);
            il.Emit(OpCodes.Stloc_0);
            // Stores the type in a local variable with index 1
            il.Emit(OpCodes.Ldarg_0);
            il.Emit(OpCodes.Ldfld, type);
            il.Emit(OpCodes.Stloc_1);
            // Create an array of the same size as the paramList
            il.Emit(OpCodes.Ldc_I4, paramList.Count);
            il.Emit(OpCodes.Newarr, typeof(object));
            foreach (var param in paramList)
            {
                int index = paramList.IndexOf(param);
                // Replaces the value of the array with an input parameter, subscript should starts at 1
                il.Emit(OpCodes.Dup);
                il.Emit(OpCodes.Ldc_I4, index);
                il.Emit(OpCodes.Ldarg_S, index + 1);
                il.Emit(OpCodes.Stelem_Ref);
            }
            il.Emit(OpCodes.Stloc_2);
            il.Emit(OpCodes.Ldloc_0);
            il.Emit(OpCodes.Ldloc_1);
            il.Emit(OpCodes.Ldloc_2);
            il.Emit(OpCodes.Call, "GetApiResult");
            il.Emit(OpCodes.Ldstr, "LOADING");
            il.Emit(OpCodes.Ret);
        }

。 il.emit（opcodes.call，“ getapiresult”）; 。我已经尝试过，但是我不知道该如何处理，您能帮上解决这个问题吗？ My goal is seems like thissample

Answer 1

简化了您的示例（从注释），您想生成类似的方法；

public string test(Object a, Object b){
    print("name","type",new object[]{
        a,
        b
    });
    return "LOADING";
}

Which would result in IL similar to;

IL_0000: ldarg.0
IL_0001: ldstr "name"
IL_0006: ldstr "type"
IL_000b: ldc.i4.2 // array size
IL_000c: newarr [System.Runtime]System.Object
IL_0011: dup
IL_0012: ldc.i4.0 // array index 0
IL_0013: ldarg.1  // argument value
IL_0014: stelem.ref
IL_0015: dup
IL_0016: ldc.i4.1 // array index 1
IL_0017: ldarg.2  // argument value
IL_0018: stelem.ref
IL_0019: call instance void C::print(string, string, object[])
IL_001e: ldstr "LOADING"
IL_0023: ret

我没有使用il.emit的实际经验，但是我建议您首先尝试准确输出该方法。然后将数组创建变成循环。修改上面具有注释的行，以相似的ldc.i4/ldarg op代码，允许您指定显式int或参数值值。