我需要使用ILGenerator在另一个程序集中使用out参数调用静态void方法。使用下面的代码，我能够调用该方法，并且它可以正确运行，但是即使本地变量已设置，也不会返回out参数。我不知道从哪里开始实际获取out参数值。
以下是我使用的代码：
public delegate void DynamicMethodDelegate(object _target, params object[] _params);
public class DynamicDelegateStaticFactory
{
public static DynamicMethodDelegate CreateMethodCaller(MethodInfo method)
{
ParameterInfo[] parameters = method.GetParameters();
Type[] args = { typeof(object), typeof(object[]) };
DynamicMethod dynam =
new DynamicMethod
(
method.Name
, method.ReturnType
, args
, typeof(DynamicDelegateStaticFactory)
, true
);
//Add parmeter attributes to the new method from the existing method
for (int i = 0; i < parameters.Length; i++)
{
dynam.DefineParameter
(
i,
parameters[i].Attributes,
parameters[i].Name
);
}
ILGenerator il = dynam.GetILGenerator();
// If method isn't static push target instance on top of stack.
if (!method.IsStatic)
{
// Argument 0 of dynamic method is target instance.
il.Emit(OpCodes.Ldarg_0);
}
// Lay out args array onto stack.
LocalBuilder[] locals = new LocalBuilder[parameters.Length];
for (int i = 0; i < parameters.Length; i++ )
{
//Push args array reference onto the stack, followed
//by the current argument index (i). The Ldelem_Ref opcode
//will resolve them to args[i].
if (parameters[i].IsOut)
{
locals[i] = il.DeclareLocal(parameters[i].ParameterType.GetElementType());
il.Emit(OpCodes.Ldloca, locals[locals.Length - 1].LocalIndex);
}
else
{
// Argument 1 of dynamic method is argument array.
il.Emit(OpCodes.Ldarg_1);
il.Emit(OpCodes.Ldc_I4, i);
il.Emit(OpCodes.Ldelem_Ref);
}
// If parameter [i] is a value type perform an unboxing.
Type parameterType = parameters[i].ParameterType;
if (parameterType.IsValueType)
{
il.Emit(OpCodes.Unbox_Any, parameterType);
}
}
if (method.IsFinal || !method.IsVirtual)
{
il.Emit(OpCodes.Call, method);
}
else
{
il.Emit(OpCodes.Callvirt, method);
}
if (method.ReturnType != typeof(void))
{
// If result is of value type it needs to be boxed
if (method.ReturnType.IsValueType)
{
il.Emit(OpCodes.Box, method.ReturnType);
}
}
else
{
il.Emit(OpCodes.Ldnull);
}
il.Emit(OpCodes.Ret);
return (DynamicMethodDelegate)dynam.CreateDelegate(typeof(DynamicMethodDelegate));
}
以下是我的称呼方式：
//Create the method
MethodInfo methodInfo = LoadXmlMethodInfo;
IlHelper.MethodHelper.DynamicMethodDelegate delegate1 = MethodHelper.DynamicDelegateStaticFactory.CreateMethodCaller(methodInfo);
//Call the method
xmlReaderWarnings = null;
object[] args = new object[] { NewTaxReturn, xml, xmlReaderWarnings };
delegate1(null, args);
//Extract the out parameter (xmlReaderWarnings)
xmlReaderWarnings = (IList)args[2]; //args[2] is reader warning out parameter.
如何正确设置out参数以检索out值？
答案 0 :(得分：3)
知道了！不得不将局部变量重新分配给我的参数数组中的out变量。最终代码
public delegate void DynamicMethodDelegate(object _target, params object[] _params);
public class DynamicDelegateStaticFactory
{
public static DynamicMethodDelegate CreateMethodCaller(MethodInfo method)
{
ParameterInfo[] parameters = method.GetParameters();
Type[] args = { typeof(object), typeof(object[]) };
DynamicMethod dynam =
new DynamicMethod
(
method.Name
, method.ReturnType
, args
, typeof(DynamicDelegateStaticFactory)
, true
);
//Add parmeter attributes to the new method from the existing method
for (int i = 0; i < parameters.Length; i++)
{
dynam.DefineParameter
(
i,
parameters[i].Attributes,
parameters[i].Name
);
}
ILGenerator il = dynam.GetILGenerator();
// If method isn't static push target instance on top of stack.
if (!method.IsStatic)
{
// Argument 0 of dynamic method is target instance.
il.Emit(OpCodes.Ldarg_0);
}
// Lay out args array onto stack.
LocalBuilder[] locals = new LocalBuilder[parameters.Length];
List<LocalBuilder> outOrRefLocals = new List<LocalBuilder>();
for (int i = 0; i < parameters.Length; i++ )
{
//Push args array reference onto the stack, followed
//by the current argument index (i). The Ldelem_Ref opcode
//will resolve them to args[i].
if (!parameters[i].IsOut)
{
// Argument 1 of dynamic method is argument array.
il.Emit(OpCodes.Ldarg_1);
il.Emit(OpCodes.Ldc_I4, i);
il.Emit(OpCodes.Ldelem_Ref);
}
// If parameter [i] is a value type perform an unboxing.
Type parameterType = parameters[i].ParameterType;
if (parameterType.IsValueType)
{
il.Emit(OpCodes.Unbox_Any, parameterType);
}
}
//Create locals for out parameters
for (int i = 0; i < parameters.Length; i++)
{
if (parameters[i].IsOut)
{
locals[i] = il.DeclareLocal(parameters[i].ParameterType.GetElementType());
il.Emit(OpCodes.Ldloca, locals[locals.Length - 1]);
}
}
if (method.IsFinal || !method.IsVirtual)
{
il.Emit(OpCodes.Call, method);
}
else
{
il.Emit(OpCodes.Callvirt, method);
}
for (int idx = 0; idx < parameters.Length; ++idx)
{
if (parameters[idx].IsOut || parameters[idx].ParameterType.IsByRef)
{
il.Emit(OpCodes.Ldarg_1);
il.Emit(OpCodes.Ldc_I4, idx);
il.Emit(OpCodes.Ldloc, locals[idx].LocalIndex);
if (parameters[idx].ParameterType.GetElementType().IsValueType)
il.Emit(OpCodes.Box, parameters[idx].ParameterType.GetElementType());
il.Emit(OpCodes.Stelem_Ref);
}
}
if (method.ReturnType != typeof(void))
{
// If result is of value type it needs to be boxed
if (method.ReturnType.IsValueType)
{
il.Emit(OpCodes.Box, method.ReturnType);
}
}
else
{
il.Emit(OpCodes.Ldnull);
}
il.Emit(OpCodes.Ret);
return (DynamicMethodDelegate)dynam.CreateDelegate(typeof(DynamicMethodDelegate));
}
private static void EmitUnboxOrCast(ILGenerator il, Type typeOnStack)
{
if (typeOnStack.IsValueType || typeOnStack.IsGenericParameter)
{
il.Emit(OpCodes.Unbox_Any, typeOnStack);
}
else
{
il.Emit(OpCodes.Castclass, typeOnStack);
}
}