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Método MethodBuilder.GetILGenerator ()

 

Publicado: noviembre de 2016

Devuelve un ILGenerator para este método con el tamaño de secuencia del lenguaje intermedio de Microsoft (MSIL) predeterminado de 64 bytes.

Espacio de nombres:   System.Reflection.Emit
Ensamblado:  mscorlib (en mscorlib.dll)

public ILGenerator GetILGenerator()

Valor devuelto

Type: System.Reflection.Emit.ILGenerator

Devuelve un objeto ILGenerator para este método.

Exception Condition
InvalidOperationException

El método no debe tener un cuerpo debido a sus marcas MethodAttributes o MethodImplAttributes, por ejemplo porque tiene la marca MethodAttributes.PinvokeImpl.

-o-

El método es genérico, pero no es una definición de método genérico. Es decir, la propiedad IsGenericMethod es true, pero la propiedad IsGenericMethodDefinition es false.

The code sample below demonstrates the contextual usage of the GetILGenerator method, creating and emitting a dynamic assembly that will calculate the dot product of two points in 3D space.


using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;


class TestILGenerator {

  	public static Type DynamicDotProductGen() {

	   Type ivType = null;
	   Type[] ctorParams = new Type[] { typeof(int),
		               		    typeof(int),
					    typeof(int)};

	   AppDomain myDomain = Thread.GetDomain();
	   AssemblyName myAsmName = new AssemblyName();
	   myAsmName.Name = "IntVectorAsm";

	   AssemblyBuilder myAsmBuilder = myDomain.DefineDynamicAssembly(
					  myAsmName, 
					  AssemblyBuilderAccess.RunAndSave);

   	   ModuleBuilder IntVectorModule = myAsmBuilder.DefineDynamicModule("IntVectorModule",
									    "Vector.dll");

	   TypeBuilder ivTypeBld = IntVectorModule.DefineType("IntVector",
						              TypeAttributes.Public);

	   FieldBuilder xField = ivTypeBld.DefineField("x", typeof(int),
                                                       FieldAttributes.Private);
	   FieldBuilder yField = ivTypeBld.DefineField("y", typeof(int), 
                                                       FieldAttributes.Private);
	   FieldBuilder zField = ivTypeBld.DefineField("z", typeof(int),
                                                       FieldAttributes.Private);


           Type objType = Type.GetType("System.Object"); 
           ConstructorInfo objCtor = objType.GetConstructor(new Type[0]);

	   ConstructorBuilder ivCtor = ivTypeBld.DefineConstructor(
					  MethodAttributes.Public,
					  CallingConventions.Standard,
					  ctorParams);
	   ILGenerator ctorIL = ivCtor.GetILGenerator();
           ctorIL.Emit(OpCodes.Ldarg_0);
           ctorIL.Emit(OpCodes.Call, objCtor);
           ctorIL.Emit(OpCodes.Ldarg_0);
           ctorIL.Emit(OpCodes.Ldarg_1);
           ctorIL.Emit(OpCodes.Stfld, xField); 
           ctorIL.Emit(OpCodes.Ldarg_0);
           ctorIL.Emit(OpCodes.Ldarg_2);
           ctorIL.Emit(OpCodes.Stfld, yField); 
           ctorIL.Emit(OpCodes.Ldarg_0);
           ctorIL.Emit(OpCodes.Ldarg_3);
           ctorIL.Emit(OpCodes.Stfld, zField); 
	   ctorIL.Emit(OpCodes.Ret); 


	   // This method will find the dot product of the stored vector
	   // with another.

	   Type[] dpParams = new Type[] { ivTypeBld };

           // Here, you create a MethodBuilder containing the
	   // name, the attributes (public, static, private, and so on),
	   // the return type (int, in this case), and a array of Type
	   // indicating the type of each parameter. Since the sole parameter
	   // is a IntVector, the very class you're creating, you will
	   // pass in the TypeBuilder (which is derived from Type) instead of 
	   // a Type object for IntVector, avoiding an exception. 

	   // -- This method would be declared in C# as:
	   //    public int DotProduct(IntVector aVector)

           MethodBuilder dotProductMthd = ivTypeBld.DefineMethod(
	    		                  "DotProduct", 
				          MethodAttributes.Public,
                                          typeof(int), 
                                          dpParams);

	   // A ILGenerator can now be spawned, attached to the MethodBuilder.

	   ILGenerator mthdIL = dotProductMthd.GetILGenerator();

 	   // Here's the body of our function, in MSIL form. We're going to find the
	   // "dot product" of the current vector instance with the passed vector 
	   // instance. For reference purposes, the equation is:
	   // (x1 * x2) + (y1 * y2) + (z1 * z2) = the dot product

	   // First, you'll load the reference to the current instance "this"
	   // stored in argument 0 (ldarg.0) onto the stack. Ldfld, the subsequent
	   // instruction, will pop the reference off the stack and look up the
	   // field "x", specified by the FieldInfo token "xField".

	   mthdIL.Emit(OpCodes.Ldarg_0);
	   mthdIL.Emit(OpCodes.Ldfld, xField);

	   // That completed, the value stored at field "x" is now atop the stack.
	   // Now, you'll do the same for the object reference we passed as a
	   // parameter, stored in argument 1 (ldarg.1). After Ldfld executed,
	   // you'll have the value stored in field "x" for the passed instance
	   // atop the stack.

	   mthdIL.Emit(OpCodes.Ldarg_1);
	   mthdIL.Emit(OpCodes.Ldfld, xField);

           // There will now be two values atop the stack - the "x" value for the
	   // current vector instance, and the "x" value for the passed instance.
	   // You'll now multiply them, and push the result onto the evaluation stack.

	   mthdIL.Emit(OpCodes.Mul_Ovf_Un);

	   // Now, repeat this for the "y" fields of both vectors.

	   mthdIL.Emit(OpCodes.Ldarg_0);
	   mthdIL.Emit(OpCodes.Ldfld, yField);
	   mthdIL.Emit(OpCodes.Ldarg_1);
	   mthdIL.Emit(OpCodes.Ldfld, yField);
	   mthdIL.Emit(OpCodes.Mul_Ovf_Un);

	   // At this time, the results of both multiplications should be atop
	   // the stack. You'll now add them and push the result onto the stack.

	   mthdIL.Emit(OpCodes.Add_Ovf_Un);

	   // Multiply both "z" field and push the result onto the stack.
	   mthdIL.Emit(OpCodes.Ldarg_0);
	   mthdIL.Emit(OpCodes.Ldfld, zField);
	   mthdIL.Emit(OpCodes.Ldarg_1);
	   mthdIL.Emit(OpCodes.Ldfld, zField);
	   mthdIL.Emit(OpCodes.Mul_Ovf_Un);

	   // Finally, add the result of multiplying the "z" fields with the
	   // result of the earlier addition, and push the result - the dot product -
	   // onto the stack.
	   mthdIL.Emit(OpCodes.Add_Ovf_Un);

	   // The "ret" opcode will pop the last value from the stack and return it
	   // to the calling method. You're all done!

	   mthdIL.Emit(OpCodes.Ret);


 	   ivType = ivTypeBld.CreateType();

	   return ivType;

 	}

	public static void Main() {

	   Type IVType = null;
           object aVector1 = null;
           object aVector2 = null;
	   Type[] aVtypes = new Type[] {typeof(int), typeof(int), typeof(int)};
           object[] aVargs1 = new object[] {10, 10, 10};
           object[] aVargs2 = new object[] {20, 20, 20};

	   // Call the  method to build our dynamic class.

	   IVType = DynamicDotProductGen();

           Console.WriteLine("---");

	   ConstructorInfo myDTctor = IVType.GetConstructor(aVtypes);
	   aVector1 = myDTctor.Invoke(aVargs1);
	   aVector2 = myDTctor.Invoke(aVargs2);

	   object[] passMe = new object[1];
           passMe[0] = (object)aVector2; 

	   Console.WriteLine("(10, 10, 10) . (20, 20, 20) = {0}",
			     IVType.InvokeMember("DotProduct",
						  BindingFlags.InvokeMethod,
						  null,
						  aVector1,
						  passMe));



	   // +++ OUTPUT +++
	   // ---
	   // (10, 10, 10) . (20, 20, 20) = 600 

	}

}

.NET Framework
Disponible desde 1.1
Silverlight
Disponible desde 2.0
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