TypeBuilder.DefineUninitializedData(String, Int32, FieldAttributes) Metod

public:
 System::Reflection::Emit::FieldBuilder ^ DefineUninitializedData(System::String ^ name, int size, System::Reflection::FieldAttributes attributes);

public System.Reflection.Emit.FieldBuilder DefineUninitializedData(string name, int size, System.Reflection.FieldAttributes attributes);

member this.DefineUninitializedData : string * int * System.Reflection.FieldAttributes -> System.Reflection.Emit.FieldBuilder

Public Function DefineUninitializedData (name As String, size As Integer, attributes As FieldAttributes) As FieldBuilder

Parametrar

Returer

Ett fält som refererar till data.

Undantag

Exempel

Följande kodexempel visar användningen av DefineUninitializedData för att skapa ett ennitialiserat datafält i en dynamisk typ:

using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;
using System.Runtime.InteropServices;
using System.Security.Permissions;

public sealed class Example
{
   public static void Main()
   {
      Type myHelloWorldType = CreateCallee(Thread.GetDomain());
      object myHelloWorldInstance =
      Activator.CreateInstance(myHelloWorldType);
      FieldInfo myGreetingFieldInfo =
      myHelloWorldType.GetField("MyGreeting");
      object oval = Activator.CreateInstance(myGreetingFieldInfo.FieldType);
      IntPtr myIntPtr = Marshal.AllocHGlobal(4);
      Random rand = new Random();
      int iTempSeed = rand.Next();
      byte[] bINITBYTE = GetRandBytes( iTempSeed, 4);
      IntPtr intptrTemp = myIntPtr;
      for ( int j = 0; j < 4; j++ )
      {
         Marshal.WriteByte( myIntPtr, bINITBYTE[j]);
         myIntPtr = (IntPtr)((int)myIntPtr + 1);
      }
      myIntPtr = intptrTemp;
      Object oValNew = Marshal.PtrToStructure( myIntPtr, myGreetingFieldInfo.FieldType);
      Marshal.FreeHGlobal( myIntPtr );

      myIntPtr = Marshal.AllocHGlobal(4);
      object myObj = myGreetingFieldInfo.GetValue(myHelloWorldInstance);
      Marshal.StructureToPtr(myObj, myIntPtr, true);
      intptrTemp = myIntPtr;
      Console.WriteLine("The value of 'MyGreeting' field : ");
      for ( int j = 0; j < 4; j++ )
      {
         Marshal.WriteByte( myIntPtr, bINITBYTE[j]);
         Console.WriteLine(bINITBYTE[j]);
         myIntPtr = (IntPtr)((int)myIntPtr + 1);
      }
   }

   private static byte[] GetRandBytes( int iRandSeed, int iSize )
   {
      byte[] barr = new byte[iSize];
      Random randTemp = new Random( iRandSeed );
      randTemp.NextBytes( barr );
      return barr;
   }

   // Create the callee transient dynamic assembly.
   private static Type CreateCallee(AppDomain myDomain)
   {
      // Create a simple name for the callee assembly.
      AssemblyName myAssemblyName = new AssemblyName();
      myAssemblyName.Name = "EmittedClass";

      // Create the callee dynamic assembly.
      AssemblyBuilder myAssembly =
         myDomain.DefineDynamicAssembly(myAssemblyName,AssemblyBuilderAccess.Run);

      // Create a dynamic module in the callee assembly.
      ModuleBuilder myModule =
         myAssembly.DefineDynamicModule("EmittedModule");

      // Define a public class named "MyHelloWorld"
      TypeBuilder myHelloWorldType =
         myModule.DefineType("MyHelloWorld", TypeAttributes.Public);

      // Define a 'MyGreeting' field and initialize it.
      FieldBuilder myFieldBuilder =
         myHelloWorldType.DefineUninitializedData("MyGreeting",4,FieldAttributes.Public);

      // Create the 'MyHelloWorld' class.
      return(myHelloWorldType.CreateType());
   }

   private Example() {}
}

Imports System.Threading
Imports System.Reflection
Imports System.Reflection.Emit
Imports System.Runtime.InteropServices


Module Example

   Sub Main()
      Dim myHelloWorldType As Type = CreateCallee(Thread.GetDomain())
      Dim myHelloWorldInstance As Object = Activator.CreateInstance(myHelloWorldType)
      Dim myGreetingFieldInfo As FieldInfo = myHelloWorldType.GetField("MyGreeting")
      Dim oval As Object = Activator.CreateInstance(myGreetingFieldInfo.FieldType)
      Dim myIntPtr As IntPtr = Marshal.AllocHGlobal(4)
      Dim rand As New Random()
      Dim iTempSeed As Integer = rand.Next()
      Dim bINITBYTE As Byte() = GetRandBytes(iTempSeed, 4)
      Dim intptrTemp As IntPtr = myIntPtr
      Dim j As Integer
      For j = 0 To 3
         Marshal.WriteByte(myIntPtr, bINITBYTE(j))
         myIntPtr = intptr.op_Explicit(myIntPtr.ToInt32 + 1)
      Next j
      myIntPtr = intptrTemp
      Dim oValNew As [Object] = Marshal.PtrToStructure(myIntPtr, myGreetingFieldInfo.FieldType)
      Marshal.FreeHGlobal(myIntPtr)

      myIntPtr = Marshal.AllocHGlobal(4)
      Dim myObj As Object = myGreetingFieldInfo.GetValue(myHelloWorldInstance)
      Marshal.StructureToPtr(myObj, myIntPtr, True)
      intptrTemp = myIntPtr
      Console.WriteLine("The value of 'MyGreeting' field : ")

      For j = 0 To 3
         Marshal.WriteByte(myIntPtr, bINITBYTE(j))
         Console.WriteLine(bINITBYTE(j))
         myIntPtr = intptr.op_Explicit(myIntPtr.ToInt32 + 1)
      Next j
   End Sub


   Private Function GetRandBytes(ByVal iRandSeed As Integer, ByVal iSize As Integer) As Byte()
      Dim barr(iSize) As Byte
      Dim randTemp As New Random(iRandSeed)
      randTemp.NextBytes(barr)
      Return barr
   End Function 'GetRandBytes


   ' Create the callee transient dynamic assembly.
   Private Function CreateCallee(ByVal myDomain As AppDomain) As Type
      ' Create a simple name for the callee assembly.
      Dim myAssemblyName As New AssemblyName()
      myAssemblyName.Name = "EmittedClass"

      ' Create the callee dynamic assembly.
      Dim myAssembly As AssemblyBuilder = myDomain.DefineDynamicAssembly(myAssemblyName, AssemblyBuilderAccess.Run)


      ' Create a dynamic module in the callee assembly.
      Dim myModule As ModuleBuilder = myAssembly.DefineDynamicModule("EmittedModule")

      ' Define a public class named "MyHelloWorld"
      Dim myHelloWorldType As TypeBuilder = myModule.DefineType("MyHelloWorld", TypeAttributes.Public)

      ' Define a 'MyGreeting' field and initialize it.
      Dim myFieldBuilder As FieldBuilder = myHelloWorldType.DefineUninitializedData("MyGreeting", 4, FieldAttributes.Public)

      ' Create the 'MyHelloWorld' class.
      Return myHelloWorldType.CreateType()
   End Function 'CreateCallee

End Module

Kommentarer

Fältet som du skapar med den här metoden blir static, även om du inte tar med FieldAttributes.Static i parametern attributes .