ConstructorBuilder Klass

Definition

public ref class ConstructorBuilder sealed : System::Reflection::ConstructorInfo, System::Runtime::InteropServices::_ConstructorBuilder

public ref class ConstructorBuilder sealed : System::Reflection::ConstructorInfo

[System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.None)]
public sealed class ConstructorBuilder : System.Reflection.ConstructorInfo, System.Runtime.InteropServices._ConstructorBuilder

[System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.None)]
[System.Runtime.InteropServices.ComVisible(true)]
public sealed class ConstructorBuilder : System.Reflection.ConstructorInfo, System.Runtime.InteropServices._ConstructorBuilder

public sealed class ConstructorBuilder : System.Reflection.ConstructorInfo

[<System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.None)>]
type ConstructorBuilder = class
    inherit ConstructorInfo
    interface _ConstructorBuilder

[<System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.None)>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type ConstructorBuilder = class
    inherit ConstructorInfo
    interface _ConstructorBuilder

type ConstructorBuilder = class
    inherit ConstructorInfo

Public NotInheritable Class ConstructorBuilder
Inherits ConstructorInfo
Implements _ConstructorBuilder

Public NotInheritable Class ConstructorBuilder
Inherits ConstructorInfo

Arv

Object

MemberInfo

MethodBase

ConstructorInfo

ConstructorBuilder

Attribut

ClassInterfaceAttribute ComVisibleAttribute

Implementeringar

_ConstructorBuilder

Exempel

Följande kodexempel illustrerar kontextuell användning av en ConstructorBuilder.

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

class TestCtorBuilder {

    public static Type DynamicPointTypeGen() {
    
       Type pointType = null;
       Type[] ctorParams = new Type[] {typeof(int),
                        typeof(int),
                        typeof(int)};
    
       AppDomain myDomain = Thread.GetDomain();
       AssemblyName myAsmName = new AssemblyName();
       myAsmName.Name = "MyDynamicAssembly";
    
       AssemblyBuilder myAsmBuilder = myDomain.DefineDynamicAssembly(
                      myAsmName,
                      AssemblyBuilderAccess.RunAndSave);

       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);
       FieldBuilder zField = pointTypeBld.DefineField("z", 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();

       // NOTE: ldarg.0 holds the "this" reference - ldarg.1, ldarg.2, and ldarg.3
       // hold the actual passed parameters. ldarg.0 is used by instance methods
       // to hold a reference to the current calling object instance. Static methods
       // do not use arg.0, since they are not instantiated and hence no reference
       // is needed to distinguish them.

           ctorIL.Emit(OpCodes.Ldarg_0);

       // Here, we wish to create an instance of System.Object by invoking its
       // constructor, as specified above.

           ctorIL.Emit(OpCodes.Call, objCtor);

       // Now, we'll load the current instance ref in arg 0, along
       // with the value of parameter "x" stored in arg 1, into stfld.

           ctorIL.Emit(OpCodes.Ldarg_0);
           ctorIL.Emit(OpCodes.Ldarg_1);
           ctorIL.Emit(OpCodes.Stfld, xField);

       // Now, we store arg 2 "y" in the current instance with stfld.

           ctorIL.Emit(OpCodes.Ldarg_0);
           ctorIL.Emit(OpCodes.Ldarg_2);
           ctorIL.Emit(OpCodes.Stfld, yField);

       // Last of all, arg 3 "z" gets stored in the current instance.

           ctorIL.Emit(OpCodes.Ldarg_0);
           ctorIL.Emit(OpCodes.Ldarg_3);
           ctorIL.Emit(OpCodes.Stfld, zField);

           // Our work complete, we return.

       ctorIL.Emit(OpCodes.Ret);

       // Now, let's create three very simple methods so we can see our fields.

       string[] mthdNames = new string[] {"GetX", "GetY", "GetZ"};

           foreach (string mthdName in mthdNames) {
              MethodBuilder getFieldMthd = pointTypeBld.DefineMethod(
                           mthdName,
                           MethodAttributes.Public,
                                           typeof(int),
                                           null);
          ILGenerator mthdIL = getFieldMthd.GetILGenerator();
    
          mthdIL.Emit(OpCodes.Ldarg_0);
          switch (mthdName) {
             case "GetX": mthdIL.Emit(OpCodes.Ldfld, xField);
                  break;
             case "GetY": mthdIL.Emit(OpCodes.Ldfld, yField);
                  break;
             case "GetZ": mthdIL.Emit(OpCodes.Ldfld, zField);
                  break;
          }
          mthdIL.Emit(OpCodes.Ret);
           }
       // Finally, we create the type.

       pointType = pointTypeBld.CreateType();

       // Let's save it, just for posterity.
    
       myAsmBuilder.Save("Point.dll");
    
       return pointType;
    }

    public static void Main() {
    
       Type myDynamicType = null;
           object aPoint = null;
       Type[] aPtypes = new Type[] {typeof(int), typeof(int), typeof(int)};
           object[] aPargs = new object[] {4, 5, 6};
    
       // Call the  method to build our dynamic class.

       myDynamicType = DynamicPointTypeGen();

       Console.WriteLine("Some information about my new Type '{0}':",
                  myDynamicType.FullName);
       Console.WriteLine("Assembly: '{0}'", myDynamicType.Assembly);
       Console.WriteLine("Attributes: '{0}'", myDynamicType.Attributes);
       Console.WriteLine("Module: '{0}'", myDynamicType.Module);
       Console.WriteLine("Members: ");
       foreach (MemberInfo member in myDynamicType.GetMembers()) {
        Console.WriteLine("-- {0} {1};", member.MemberType, member.Name);
       }

           Console.WriteLine("---");

       // Let's take a look at the constructor we created.

       ConstructorInfo myDTctor = myDynamicType.GetConstructor(aPtypes);
           Console.WriteLine("Constructor: {0};", myDTctor.ToString());

           Console.WriteLine("---");
    
           // Now, we get to use our dynamically-created class by invoking the constructor.

       aPoint = myDTctor.Invoke(aPargs);
           Console.WriteLine("aPoint is type {0}.", aPoint.GetType());

       // Finally, let's reflect on the instance of our new type - aPoint - and
       // make sure everything proceeded according to plan.

       Console.WriteLine("aPoint.x = {0}",
                 myDynamicType.InvokeMember("GetX",
                                BindingFlags.InvokeMethod,
                            null,
                            aPoint,
                            new object[0]));
       Console.WriteLine("aPoint.y = {0}",
                 myDynamicType.InvokeMember("GetY",
                                BindingFlags.InvokeMethod,
                            null,
                            aPoint,
                            new object[0]));
       Console.WriteLine("aPoint.z = {0}",
                 myDynamicType.InvokeMember("GetZ",
                                BindingFlags.InvokeMethod,
                            null,
                            aPoint,
                            new object[0]));

       // +++ OUTPUT +++
       // Some information about my new Type 'Point':
       // Assembly: 'MyDynamicAssembly, Version=0.0.0.0'
       // Attributes: 'AutoLayout, AnsiClass, NotPublic, Public'
       // Module: 'PointModule'
       // Members:
       // -- Field x;
       // -- Field y;
       // -- Field z;
           // -- Method GetHashCode;
           // -- Method Equals;
           // -- Method ToString;
           // -- Method GetType;
           // -- Constructor .ctor;
       // ---
       // Constructor: Void .ctor(Int32, Int32, Int32);
       // ---
       // aPoint is type Point.
       // aPoint.x = 4
       // aPoint.y = 5
       // aPoint.z = 6
    }
}

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

 _

Class TestCtorBuilder
   
   
   Public Shared Function DynamicPointTypeGen() As Type
      
      Dim pointType As Type = Nothing
      Dim ctorParams() As Type = {GetType(Integer), 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 zField As FieldBuilder = pointTypeBld.DefineField("z", 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()
      
      ' NOTE: ldarg.0 holds the "this" reference - ldarg.1, ldarg.2, and ldarg.3
      ' hold the actual passed parameters. ldarg.0 is used by instance methods
      ' to hold a reference to the current calling object instance. Static methods
      ' do not use arg.0, since they are not instantiated and hence no reference
      ' is needed to distinguish them. 
      ctorIL.Emit(OpCodes.Ldarg_0)
      
      ' Here, we wish to create an instance of System.Object by invoking its
      ' constructor, as specified above.
      ctorIL.Emit(OpCodes.Call, objCtor)
      
      ' Now, we'll load the current instance ref in arg 0, along
      ' with the value of parameter "x" stored in arg 1, into stfld.
      ctorIL.Emit(OpCodes.Ldarg_0)
      ctorIL.Emit(OpCodes.Ldarg_1)
      ctorIL.Emit(OpCodes.Stfld, xField)
      
      ' Now, we store arg 2 "y" in the current instance with stfld.
      ctorIL.Emit(OpCodes.Ldarg_0)
      ctorIL.Emit(OpCodes.Ldarg_2)
      ctorIL.Emit(OpCodes.Stfld, yField)
      
      ' Last of all, arg 3 "z" gets stored in the current instance.
      ctorIL.Emit(OpCodes.Ldarg_0)
      ctorIL.Emit(OpCodes.Ldarg_3)
      ctorIL.Emit(OpCodes.Stfld, zField)
      
      ' Our work complete, we return.
      ctorIL.Emit(OpCodes.Ret)
      
      ' Now, let's create three very simple methods so we can see our fields.
      Dim mthdNames() As String = {"GetX", "GetY", "GetZ"}
      
      Dim mthdName As String
      For Each mthdName In  mthdNames
         Dim getFieldMthd As MethodBuilder = pointTypeBld.DefineMethod(mthdName, MethodAttributes.Public, GetType(Integer), Nothing)
         Dim mthdIL As ILGenerator = getFieldMthd.GetILGenerator()
         
         mthdIL.Emit(OpCodes.Ldarg_0)
         Select Case mthdName
            Case "GetX"
               mthdIL.Emit(OpCodes.Ldfld, xField)
            Case "GetY"
               mthdIL.Emit(OpCodes.Ldfld, yField)
            Case "GetZ"
               mthdIL.Emit(OpCodes.Ldfld, zField)
         End Select
         
         mthdIL.Emit(OpCodes.Ret)
      Next mthdName 
      ' Finally, we create the type.
      pointType = pointTypeBld.CreateType()
      
      ' Let's save it, just for posterity.
      myAsmBuilder.Save("Point.dll")
      
      Return pointType
   End Function 'DynamicPointTypeGen
    
   
   Public Shared Sub Main()
      
      Dim myDynamicType As Type = Nothing
      Dim aPoint As Object = Nothing
      Dim aPtypes() As Type = {GetType(Integer), GetType(Integer), GetType(Integer)}
      Dim aPargs() As Object = {4, 5, 6}
      
      ' Call the  method to build our dynamic class.
      myDynamicType = DynamicPointTypeGen()
      
      Console.WriteLine("Some information about my new Type '{0}':", myDynamicType.FullName)
      Console.WriteLine("Assembly: '{0}'", myDynamicType.Assembly)
      Console.WriteLine("Attributes: '{0}'", myDynamicType.Attributes)
      Console.WriteLine("Module: '{0}'", myDynamicType.Module)
      Console.WriteLine("Members: ")
      Dim member As MemberInfo
      For Each member In  myDynamicType.GetMembers()
         Console.WriteLine("-- {0} {1};", member.MemberType, member.Name)
      Next member
      
      Console.WriteLine("---")
      
      ' Let's take a look at the constructor we created.
      Dim myDTctor As ConstructorInfo = myDynamicType.GetConstructor(aPtypes)
      Console.WriteLine("Constructor: {0};", myDTctor.ToString())
      
      Console.WriteLine("---")
      
      ' Now, we get to use our dynamically-created class by invoking the constructor. 
      aPoint = myDTctor.Invoke(aPargs)
      Console.WriteLine("aPoint is type {0}.", aPoint.GetType())
      
      
      ' Finally, let's reflect on the instance of our new type - aPoint - and
      ' make sure everything proceeded according to plan.
      Console.WriteLine("aPoint.x = {0}", myDynamicType.InvokeMember("GetX", BindingFlags.InvokeMethod, Nothing, aPoint, New Object() {}))
      Console.WriteLine("aPoint.y = {0}", myDynamicType.InvokeMember("GetY", BindingFlags.InvokeMethod, Nothing, aPoint, New Object() {}))
      Console.WriteLine("aPoint.z = {0}", myDynamicType.InvokeMember("GetZ", BindingFlags.InvokeMethod, Nothing, aPoint, New Object() {}))
   End Sub
End Class



' +++ OUTPUT +++
' Some information about my new Type 'Point':
' Assembly: 'MyDynamicAssembly, Version=0.0.0.0'
' Attributes: 'AutoLayout, AnsiClass, NotPublic, Public'
' Module: 'PointModule'
' Members: 
' -- Field x;
' -- Field y;
' -- Field z;
' -- Method GetHashCode;
' -- Method Equals;
' -- Method ToString;
' -- Method GetType;
' -- Constructor .ctor;
' ---
' Constructor: Void .ctor(Int32, Int32, Int32);
' ---
' aPoint is type Point.
' aPoint.x = 4
' aPoint.y = 5
' aPoint.z = 6

Kommentarer

ConstructorBuilder används för att helt beskriva en konstruktor i Microsoft mellanliggande språk (MSIL), inklusive namn, attribut, signatur och konstruktortext. Den används tillsammans med TypeBuilder klassen för att skapa klasser vid körning. Anropa DefineConstructor för att hämta en instans av ConstructorBuilder.

Om du inte definierar en konstruktor för din dynamiska typ tillhandahålls en parameterlös konstruktor automatiskt och anropar den parameterlösa konstruktorn för basklassen.

Om du använder ConstructorBuilder för att definiera en konstruktor för din dynamiska typ tillhandahålls ingen parameterlös konstruktor. Du har följande alternativ för att tillhandahålla en parameterlös konstruktor utöver konstruktorn som du definierade:

• Om du vill ha en parameterlös konstruktor som helt enkelt anropar den parameterlösa konstruktorn för basklassen TypeBuilder.DefineDefaultConstructor kan du använda metoden för att skapa en (och eventuellt begränsa åtkomsten till den). Ange ingen implementering för den här parameterlösa konstruktorn. Om du gör det utlöses ett undantag när du försöker använda konstruktorn. Inget undantag utlöses när TypeBuilder.CreateType metoden anropas.

• Om du vill ha en parameterlös konstruktor som gör något mer än att bara anropa den parameterlösa konstruktorn för basklassen, eller som anropar en annan konstruktor i basklassen, eller som gör något helt annat, måste du använda TypeBuilder.DefineConstructor metoden för att skapa en ConstructorBuilder, och tillhandahålla din egen implementering.