OpCodes 类

定义

public ref class OpCodes

public class OpCodes

[System.Runtime.InteropServices.ComVisible(true)]
public class OpCodes

type OpCodes = class

[<System.Runtime.InteropServices.ComVisible(true)>]
type OpCodes = class

Public Class OpCodes

继承

Object

OpCodes

属性

ComVisibleAttribute

示例

以下示例演示了使用 ILGenerator 发出到 OpCodes 的 MethodBuilder动态方法的构造。

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

class EmitWriteLineDemo {

   public static Type CreateDynamicType() {
       Type[] ctorParams = new Type[] {typeof(int),
                   typeof(int)};
    
       AppDomain myDomain = Thread.GetDomain();
       AssemblyName myAsmName = new AssemblyName();
       myAsmName.Name = "MyDynamicAssembly";

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

       ModuleBuilder pointModule = myAsmBuilder.DefineDynamicModule("PointModule",
                                    "Point.dll");

       TypeBuilder pointTypeBld = pointModule.DefineType("Point",
                                  TypeAttributes.Public);

       FieldBuilder xField = pointTypeBld.DefineField("x", typeof(int),
                                                      FieldAttributes.Public);
       FieldBuilder yField = pointTypeBld.DefineField("y", typeof(int),
                                                      FieldAttributes.Public);

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

       ConstructorBuilder pointCtor = pointTypeBld.DefineConstructor(
                                   MethodAttributes.Public,
                                   CallingConventions.Standard,
                                   ctorParams);
       ILGenerator ctorIL = pointCtor.GetILGenerator();

       // First, you build the constructor.
       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.Ret);

       //  Now, you'll build a method to output some information on the
       // inside your dynamic class. This method will have the following
       // definition in C#:
    //  public void WritePoint()

       MethodBuilder writeStrMthd = pointTypeBld.DefineMethod(
                                     "WritePoint",
                             MethodAttributes.Public,
                                             typeof(void),
                                             null);

       ILGenerator writeStrIL = writeStrMthd.GetILGenerator();

       // The below ILGenerator created demonstrates a few ways to create
       // string output through STDIN.

       // ILGenerator.EmitWriteLine(string) will generate a ldstr and a
       // call to WriteLine for you.

       writeStrIL.EmitWriteLine("The value of this current instance is:");

       // Here, you will do the hard work yourself. First, you need to create
       // the string we will be passing and obtain the correct WriteLine overload
       // for said string. In the below case, you are substituting in two values,
       // so the chosen overload is Console.WriteLine(string, object, object).

       String inStr = "({0}, {1})";
       Type[] wlParams = new Type[] {typeof(string),
                     typeof(object),
                     typeof(object)};

       // We need the MethodInfo to pass into EmitCall later.

       MethodInfo writeLineMI = typeof(Console).GetMethod(
                            "WriteLine",
                        wlParams);

       // Push the string with the substitutions onto the stack.
       // This is the first argument for WriteLine - the string one.

       writeStrIL.Emit(OpCodes.Ldstr, inStr);

       // Since the second argument is an object, and it corresponds to
       // to the substitution for the value of our integer field, you
       // need to box that field to an object. First, push a reference
       // to the current instance, and then push the value stored in
       // field 'x'. We need the reference to the current instance (stored
       // in local argument index 0) so Ldfld can load from the correct
       // instance (this one).

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

       // Now, we execute the box opcode, which pops the value of field 'x',
       // returning a reference to the integer value boxed as an object.

       writeStrIL.Emit(OpCodes.Box, typeof(int));

       // Atop the stack, you'll find our string inStr, followed by a reference
       // to the boxed value of 'x'. Now, you need to likewise box field 'y'.

       writeStrIL.Emit(OpCodes.Ldarg_0);
       writeStrIL.Emit(OpCodes.Ldfld, yField);
       writeStrIL.Emit(OpCodes.Box, typeof(int));

       // Now, you have all of the arguments for your call to
       // Console.WriteLine(string, object, object) atop the stack:
       // the string InStr, a reference to the boxed value of 'x', and
       // a reference to the boxed value of 'y'.

       // Call Console.WriteLine(string, object, object) with EmitCall.

       writeStrIL.EmitCall(OpCodes.Call, writeLineMI, null);

       // Lastly, EmitWriteLine can also output the value of a field
       // using the overload EmitWriteLine(FieldInfo).

       writeStrIL.EmitWriteLine("The value of 'x' is:");
       writeStrIL.EmitWriteLine(xField);
       writeStrIL.EmitWriteLine("The value of 'y' is:");
       writeStrIL.EmitWriteLine(yField);

       // Since we return no value (void), the ret opcode will not
       // return the top stack value.

       writeStrIL.Emit(OpCodes.Ret);

       return pointTypeBld.CreateType();
   }

   public static void Main() {

      object[] ctorParams = new object[2];

      Console.Write("Enter a integer value for X: ");
      string myX = Console.ReadLine();
      Console.Write("Enter a integer value for Y: ");
      string myY = Console.ReadLine();

      Console.WriteLine("---");

      ctorParams[0] = Convert.ToInt32(myX);
      ctorParams[1] = Convert.ToInt32(myY);

      Type ptType = CreateDynamicType();

      object ptInstance = Activator.CreateInstance(ptType, ctorParams);
      ptType.InvokeMember("WritePoint",
              BindingFlags.InvokeMethod,
              null,
              ptInstance,
              new object[0]);
   }
}

Imports System.Threading
Imports System.Reflection
Imports System.Reflection.Emit

 _

Class EmitWriteLineDemo
   
   
   Public Shared Function CreateDynamicType() As Type

      Dim ctorParams() As Type = {GetType(Integer), GetType(Integer)}
      
      Dim myDomain As AppDomain = Thread.GetDomain()
      Dim myAsmName As New AssemblyName()
      myAsmName.Name = "MyDynamicAssembly"
      
      Dim myAsmBuilder As AssemblyBuilder = myDomain.DefineDynamicAssembly(myAsmName, AssemblyBuilderAccess.RunAndSave)
      
      Dim pointModule As ModuleBuilder = myAsmBuilder.DefineDynamicModule("PointModule", "Point.dll")
      
      Dim pointTypeBld As TypeBuilder = pointModule.DefineType("Point", _
                                   TypeAttributes.Public)
      
      Dim xField As FieldBuilder = pointTypeBld.DefineField("x", _
                                GetType(Integer), _
                                FieldAttributes.Public)
      Dim yField As FieldBuilder = pointTypeBld.DefineField("y", _
                                GetType(Integer), _
                                FieldAttributes.Public)
      
      
      Dim objType As Type = Type.GetType("System.Object")
      Dim objCtor As ConstructorInfo = objType.GetConstructor(New Type(){})
      
      Dim pointCtor As ConstructorBuilder = pointTypeBld.DefineConstructor( _
                             MethodAttributes.Public, _
                             CallingConventions.Standard, _
                             ctorParams)
      Dim ctorIL As ILGenerator = pointCtor.GetILGenerator()
      
      
      ' First, you build the constructor.

      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.Ret)
      
      '  Now, you'll build a method to output some information on the
      ' inside your dynamic class. This method will have the following
      ' definition in C#:
      '  Public Sub WritePoint() 

      Dim writeStrMthd As MethodBuilder = pointTypeBld.DefineMethod("WritePoint", _
                                    MethodAttributes.Public, _
                                    Nothing, Nothing)
      
      Dim writeStrIL As ILGenerator = writeStrMthd.GetILGenerator()
      
      ' The below ILGenerator created demonstrates a few ways to create
      ' string output through STDIN. 
      ' ILGenerator.EmitWriteLine(string) will generate a ldstr and a 
      ' call to WriteLine for you.

      writeStrIL.EmitWriteLine("The value of this current instance is:")
      
      ' Here, you will do the hard work yourself. First, you need to create
      ' the string we will be passing and obtain the correct WriteLine overload
      ' for said string. In the below case, you are substituting in two values,
      ' so the chosen overload is Console.WriteLine(string, object, object).

      Dim inStr As [String] = "({0}, {1})"
      Dim wlParams() As Type = {GetType(String), GetType(Object), GetType(Object)}
      
      ' We need the MethodInfo to pass into EmitCall later.

      Dim writeLineMI As MethodInfo = GetType(Console).GetMethod("WriteLine", wlParams)
      
      ' Push the string with the substitutions onto the stack.
      ' This is the first argument for WriteLine - the string one. 

      writeStrIL.Emit(OpCodes.Ldstr, inStr)
      
      ' Since the second argument is an object, and it corresponds to
      ' to the substitution for the value of our integer field, you 
      ' need to box that field to an object. First, push a reference
      ' to the current instance, and then push the value stored in
      ' field 'x'. We need the reference to the current instance (stored
      ' in local argument index 0) so Ldfld can load from the correct
      ' instance (this one).

      writeStrIL.Emit(OpCodes.Ldarg_0)
      writeStrIL.Emit(OpCodes.Ldfld, xField)
      
      ' Now, we execute the box opcode, which pops the value of field 'x',
      ' returning a reference to the integer value boxed as an object.

      writeStrIL.Emit(OpCodes.Box, GetType(Integer))
      
      ' Atop the stack, you'll find our string inStr, followed by a reference
      ' to the boxed value of 'x'. Now, you need to likewise box field 'y'.

      writeStrIL.Emit(OpCodes.Ldarg_0)
      writeStrIL.Emit(OpCodes.Ldfld, yField)
      writeStrIL.Emit(OpCodes.Box, GetType(Integer))
      
      ' Now, you have all of the arguments for your call to
      ' Console.WriteLine(string, object, object) atop the stack:
      ' the string InStr, a reference to the boxed value of 'x', and
      ' a reference to the boxed value of 'y'.
      ' Call Console.WriteLine(string, object, object) with EmitCall.

      writeStrIL.EmitCall(OpCodes.Call, writeLineMI, Nothing)
      
      ' Lastly, EmitWriteLine can also output the value of a field
      ' using the overload EmitWriteLine(FieldInfo).

      writeStrIL.EmitWriteLine("The value of 'x' is:")
      writeStrIL.EmitWriteLine(xField)
      writeStrIL.EmitWriteLine("The value of 'y' is:")
      writeStrIL.EmitWriteLine(yField)
      
      ' Since we return no value (void), the ret opcode will not
      ' return the top stack value.

      writeStrIL.Emit(OpCodes.Ret)
      
      Return pointTypeBld.CreateType()

   End Function 'CreateDynamicType
    
   
   Public Shared Sub Main()
      
      Dim ctorParams(1) As Object
      
      Console.Write("Enter a integer value for X: ")
      Dim myX As String = Console.ReadLine()
      Console.Write("Enter a integer value for Y: ")
      Dim myY As String = Console.ReadLine()
      
      Console.WriteLine("---")
      
      ctorParams(0) = Convert.ToInt32(myX)
      ctorParams(1) = Convert.ToInt32(myY)
      
      Dim ptType As Type = CreateDynamicType()

      Dim ptInstance As Object = Activator.CreateInstance(ptType, ctorParams)

      ptType.InvokeMember("WritePoint", _
              BindingFlags.InvokeMethod, _
              Nothing, ptInstance, Nothing)

   End Sub

End Class

注解

有关成员操作代码的详细说明，请参阅公共语言基础结构 (CLI) 文档，特别是“分区 III：CIL 指令集”和“分区 II：元数据定义和语义”。 有关详细信息，请参阅 ECMA 335 公共语言基础结构 (CLI) 。