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c# – IL使用Reflection.Emit调用params object []参数的方法

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我正在编写一个需要后续类型构建的库.库使用平台.Net core 2.0

我使用Reflection.Emit生成某些类型的问题

public class GeneratedA : A, IA
{
    public void DoInterface(string arg0, bool arg1, int arg2, object arg3, List<float> arg4, params object[] otherArgs)
    {
        DoClass(arg0, arg1, arg2, arg3, arg4, otherArgs);
    }
}

对于这些类型:

public interface IA
{
    void DoInterface(string arg0, bool arg1, int arg2, object arg3, List<float> arg4,  params object[] otherArgs);
}
public class A
{
    public void DoClass(params object[] args)
    {
    }
}

样本IL代码:

class Program
{
    public static class Generator
    {
        public static T Create<T>()
            where T : class
        {
            AssemblyName aName = new AssemblyName("DynamicAssembly");
            AssemblyBuilder ab = AssemblyBuilder.DefineDynamicAssembly(new AssemblyName(Guid.NewGuid().ToString()), AssemblyBuilderAccess.Run);
            ModuleBuilder mb = ab.DefineDynamicModule(aName.Name);

            var interfaceType = typeof(T);
            var interfaceMethod = interfaceType.GetMethod("DoInterface");
            var interfaceMethodArgs = interfaceMethod.GetParameters().Select(x => x.ParameterType).ToArray();
            var classType = typeof(A);
            var classMethod = classType.GetMethod("DoClass");
            var returnType = typeof(void);
            var baseType = typeof(object);
            var baseConstructor = baseType.GetConstructor(BindingFlags.Public | BindingFlags.FlattenHierarchy | BindingFlags.Instance, null, Type.EmptyTypes, null);


            TypeBuilder tb = mb.DefineType("GeneratedA", TypeAttributes.Public, baseType);


            ConstructorBuilder ctor = tb.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, Type.EmptyTypes);
            ILGenerator ctorIL = ctor.GetILGenerator();
            ctorIL.Emit(OpCodes.Ldarg_0);
            ctorIL.Emit(OpCodes.Call, baseConstructor);
            ctorIL.Emit(OpCodes.Nop);
            ctorIL.Emit(OpCodes.Nop);
            ctorIL.Emit(OpCodes.Ret);


            tb.AddInterfaceImplementation(interfaceType);

            MethodBuilder mbIM = tb.DefineMethod(interfaceType.Name + "." + interfaceMethod.Name,
                MethodAttributes.Private | MethodAttributes.HideBySig |
                MethodAttributes.NewSlot | MethodAttributes.Virtual |
                MethodAttributes.Final,
                returnType,
                interfaceMethodArgs);
            ILGenerator genIM = mbIM.GetILGenerator();
            // ToDo
            genIM.Emit(OpCodes.Call, classMethod);
            genIM.Emit(OpCodes.Ret);


            tb.DefineMethodOverride(mbIM, interfaceMethod);

            Type t = tb.CreateType();

            return Activator.CreateInstance(t) as T;
        }

    }

    static void Main(string[] args)
    {
        IA a;
        a = new GeneratedA();
        a.DoInterface("0", true, 2, 3, new List<float>() { 4 }, "5", 6);
        a = Generator.Create<IA>();
        a.DoInterface("0", true, 2, 3, new List<float>() { 4 }, "5", 6);
    }
}

每当我尝试填写评论“ToDo”时,我都会收到错误“Common Language Runtime检测到无效程序”.

我请求帮助调用方法DoClass.

谢谢

解决方法:

要调用DoClass方法,您需要提供参数,只需调用classMethod就行了.

第一个参数当然是“这个”参考:

genIM.Emit(OpCodes.Ldarg_0);

第二个参数是对象数组. params是编译器功能,如果您自己构建代码 – 您必须将其视为params不在那里.我的意思是 – 同时

 DoClass();

在代码中编写它是合法的 – 这被编译为:

DoClass(new object[0]);

因此,当您发出此调用时 – 您应该始终提供对象数组参数,您不能省略它.

要将对象数组推送到堆栈:

// push array length (0, for example) to stack
genIM.Emit(OpCodes.Ldc_I4_0); 
// push new array with length given by the above value (0)
genIM.Emit(OpCodes.Newarr, typeof(object)); 

此时您的代码将编译并运行正常.这类似于:

public class GeneratedA : A, IA
{
    public void DoInterface(string arg0, bool arg1, int arg2, object arg3, List<float> arg4, params object[] otherArgs)
    {
        DoClass();
    }
}

如果要传递DoInterface的所有参数,则需要更多工作.我将提供几个例子.传递第一个参数(字符串arg0):

genIM.Emit(OpCodes.Dup);
// push index to store next element at (0)
genIM.Emit(OpCodes.Ldc_I4_0);
// push first argument (arg0 of DoInterface) to stack
genIM.Emit(OpCodes.Ldarg_1);
// store element in array at given index (yourArguments[0] = arg0)
genIM.Emit(OpCodes.Stelem_Ref);

传递第二个参数:

genIM.Emit(OpCodes.Dup);
// push index to store next element at (1)
genIM.Emit(OpCodes.Ldc_I4_1);
// push arg2
genIM.Emit(OpCodes.Ldarg_2);
// box, because boolean is value type, and you store it in object array
genIM.Emit(OpCodes.Box, typeof(bool));
// store in array (yourArguments[1] = (object) arg2
genIM.Emit(OpCodes.Stelem_Ref);

等等.

当您将参数推入数组时,不要忘记更改其长度以反映参数的数量:

// push array length - 6
genIM.Emit(OpCodes.Ldc_I4_6); 
// push new array with length given by the above value (6)
genIM.Emit(OpCodes.Newarr, typeof(object)); 

另请注意,您可能想要更改:

TypeBuilder tb = mb.DefineType("GeneratedA", TypeAttributes.Public, baseType);

TypeBuilder tb = mb.DefineType("GeneratedA", TypeAttributes.Public, classType);

或者只是更改为baseType = typeof(A),因为您要从A继承生成的类,而不是从对象继承.

使用前2个args发出调用的完整代码:

ILGenerator genIM = mbIM.GetILGenerator();            
genIM.Emit(OpCodes.Ldarg_0);   
genIM.Emit(OpCodes.Ldc_I4_2);
genIM.Emit(OpCodes.Newarr, typeof(object));

genIM.Emit(OpCodes.Dup);
genIM.Emit(OpCodes.Ldc_I4_0);
genIM.Emit(OpCodes.Ldarg_1);
genIM.Emit(OpCodes.Stelem_Ref);

genIM.Emit(OpCodes.Dup);
genIM.Emit(OpCodes.Ldc_I4_1);
genIM.Emit(OpCodes.Ldarg_2);
genIM.Emit(OpCodes.Box, typeof(bool));
genIM.Emit(OpCodes.Stelem_Ref);

genIM.Emit(OpCodes.Call, classMethod);
genIM.Emit(OpCodes.Ret);

标签:c,cil,reflection-emit
来源: https://codeday.me/bug/20190607/1195124.html