TypeBuilder.GetConstructor(Type, ConstructorInfo) TypeBuilder.GetConstructor(Type, ConstructorInfo) TypeBuilder.GetConstructor(Type, ConstructorInfo) Method

定义

返回与指定泛型类型定义的构造函数相对应的指定构造泛型类型的构造函数。Returns the constructor of the specified constructed generic type that corresponds to the specified constructor of the generic type definition.

public:
 static System::Reflection::ConstructorInfo ^ GetConstructor(Type ^ type, System::Reflection::ConstructorInfo ^ constructor);
public static System.Reflection.ConstructorInfo GetConstructor (Type type, System.Reflection.ConstructorInfo constructor);
static member GetConstructor : Type * System.Reflection.ConstructorInfo -> System.Reflection.ConstructorInfo

参数

type
Type Type Type

已返回其构造函数的构造泛型类型。The constructed generic type whose constructor is returned.

constructor
ConstructorInfo ConstructorInfo ConstructorInfo

基于 type 的泛型类型定义的构造函数,该函数指定要返回 type 的哪个构造函数A constructor on the generic type definition of type, which specifies which constructor of type to return.

返回

ConstructorInfo 对象,它表示与 constructor 对应的 type 的构造函数,它指定属于 type 的泛型类型定义的构造函数 。A ConstructorInfo object that represents the constructor of type corresponding to constructor, which specifies a constructor belonging to the generic type definition of type.

异常

type 不表示泛型类型。type does not represent a generic type.

- 或 --or- type 的类型不是 TypeBuildertype is not of type TypeBuilder.

- 或 --or- constructor 的声明类型不是一个泛型类型定义。The declaring type of constructor is not a generic type definition.

- 或 --or- constructor 的声明类型不是 type 的泛型类型定义。The declaring type of constructor is not the generic type definition of type.

示例

下面的代码示例包含一个名为的类型Sample T参数的名为的泛型类的源代码。The following code example contains source code for a generic class named Sample that has a type parameter named T. 类具有Field一个名为、类型T为的字段GM和一个名为的泛型方法,该方法具有其U自己的类型参数(名为)。The class has a field named Field, of type T, and a generic method named GM with its own type parameter, named U. 方法GM创建的Sample实例,将其自己的类型参数U替换为的类型参数Sample,并在中Field存储其输入参数。Method GM creates an instance of Sample, substituting its own type parameter U for the type parameter of Sample, and stores its input parameter in Field. 已编译但未使用此源代码;您可以使用Ildasm (IL 拆装器)查看它并将其与类Example发出的代码进行比较。This source code is compiled but not used; you can view it with the Ildasm.exe (IL Disassembler) and compare it to the code emitted by class Example.

Example中的代码演示如何使用GetConstructor方法发出泛型代码。The code in class Example demonstrates the use of the GetConstructor method to emit generic code. Main Sample DefineGenericParameters T的方法创建一个包含名为的类的动态程序集,并使用方法通过添加一个名为的类型参数来使其成为泛型。 ExampleThe Main method of class Example creates a dynamic assembly containing a class named Sample and uses the DefineGenericParameters method to make it generic by adding a type parameter named T. 向类Field T添加了一个无参数的构造函数和一个名为的类型Sample为的字段。A parameterless constructor and a field named Field, of type T, are added to class Sample. 使用方法添加并转换为泛型方法的方法GMMethodBuilder.DefineGenericParametersA method GM is added and turned into a generic method by using the MethodBuilder.DefineGenericParameters method. GM类型参数命名U为。The type parameter of GM is named U. 定义类型参数后, GM MethodBuilder.SetSignature使用方法添加的签名。After the type parameter is defined, the signature of GM is added by using the MethodBuilder.SetSignature method. 没有返回类型,并且没有必需的修饰符或自定义修饰符,因此此方法null的所有参数除外; parameterTypes将方法的唯一参数的类型设置为U,方法的泛型类型参数。 parameterTypesThere is no return type and no required or custom modifiers, so all the parameters of this method are null except parameterTypes; parameterTypes sets the type of the method's only parameter to U, the method's generic type parameter. 方法的Sample<U>主体创建构造类型的实例(Sample(Of U)在 Visual Basic 中),将该方法的参数分配给Field,然后输出的值FieldThe body of the method creates an instance of the constructed type Sample<U> (Sample(Of U) in Visual Basic), assigns the method's parameter to Field, and then prints the value of Field. 方法用于在创建实例的OpCodes.Newobj指令ConstructorInfo中创建表示构造泛型类型Sample<U>的无参数构造函数的。 GetConstructorThe GetConstructor method is used to create a ConstructorInfo that represents the parameterless constructor of the constructed generic type Sample<U> in the OpCodes.Newobj instruction that creates the instance.

定义了一个虚拟类型来容纳入口点方法MainA dummy type is defined to hold the entry-point method Main. 在的Main正文中,将对GM构造的泛型类型Sample<int>Sample(Of Integer)在 Visual Basic 中)调用静态方法,并将String类型替换U为。In the body of Main, the static GM method is invoked on the constructed generic type Sample<int> (Sample(Of Integer) in Visual Basic), with type String substituted for U.

运行代码示例时,它会将发出的程序集保存为 TypeBuilderGetFieldExample。When the code example is run, it saves the emitted assembly as TypeBuilderGetFieldExample.exe. 您可以运行 TypeBuilderGetFieldExample,并且可以使用Ildasm (IL 拆装器)将发出的代码与编译到代码示例本身中的Sample类的代码进行比较。You can run TypeBuilderGetFieldExample.exe, and you can use the Ildasm.exe (IL Disassembler) to compare the emitted code with the code for the Sample class that is compiled into the code example itself.

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

// Compare the MSIL in this class to the MSIL
// generated by the Reflection.Emit code in class
// Example.
public class Sample<T>
{
  public T Field;
  public static void GM<U>(U val)
  {
    Sample<U> s = new Sample<U>();
    s.Field = val;
    Console.WriteLine(s.Field);
  }
}

public class Example
{
    public static void Main()
    {
        AppDomain myDomain = AppDomain.CurrentDomain;
        AssemblyName myAsmName = 
            new AssemblyName("TypeBuilderGetFieldExample");
        AssemblyBuilder myAssembly = myDomain.DefineDynamicAssembly(
            myAsmName, AssemblyBuilderAccess.Save);
        ModuleBuilder myModule = myAssembly.DefineDynamicModule(
            myAsmName.Name, 
            myAsmName.Name + ".exe");

        // Define the sample type.
        TypeBuilder myType = myModule.DefineType("Sample", 
            TypeAttributes.Class | TypeAttributes.Public);

        // Add a type parameter, making the type generic.
        string[] typeParamNames = {"T"};  
        GenericTypeParameterBuilder[] typeParams = 
            myType.DefineGenericParameters(typeParamNames);

        // Define a default constructor. Normally it would 
        // not be necessary to define the default constructor,
        // but in this case it is needed for the call to
        // TypeBuilder.GetConstructor, which gets the default
        // constructor for the generic type constructed from 
        // Sample<T>, in the generic method GM<U>.
        ConstructorBuilder ctor = myType.DefineDefaultConstructor(
            MethodAttributes.PrivateScope | MethodAttributes.Public |
            MethodAttributes.HideBySig | MethodAttributes.SpecialName |
            MethodAttributes.RTSpecialName);

        // Add a field of type T, with the name Field.
        FieldBuilder myField = myType.DefineField("Field", 
            typeParams[0],
            FieldAttributes.Public);

        // Add a method and make it generic, with a type 
        // parameter named U. Note how similar this is to 
        // the way Sample is turned into a generic type. The
        // method has no signature, because the type of its
        // only parameter is U, which is not yet defined.
        MethodBuilder genMethod = myType.DefineMethod("GM", 
            MethodAttributes.Public | MethodAttributes.Static);
        string[] methodParamNames = {"U"};
        GenericTypeParameterBuilder[] methodParams = 
            genMethod.DefineGenericParameters(methodParamNames);
        
        // Now add a signature for genMethod, specifying U
        // as the type of the parameter. There is no return value
        // and no custom modifiers.
        genMethod.SetSignature(null, null, null, 
            new Type[] { methodParams[0] }, null, null);

        // Emit a method body for the generic method.
        ILGenerator ilg = genMethod.GetILGenerator();
        // Construct the type Sample<U> using MakeGenericType.
        Type SampleOfU = myType.MakeGenericType( methodParams[0] );
        // Create a local variable to store the instance of
        // Sample<U>.
        ilg.DeclareLocal(SampleOfU);
        // Call the default constructor. Note that it is 
        // necessary to have the default constructor for the
        // constructed generic type Sample<U>; use the 
        // TypeBuilder.GetConstructor method to obtain this 
        // constructor.
        ConstructorInfo ctorOfU = TypeBuilder.GetConstructor(
            SampleOfU, ctor);
        ilg.Emit(OpCodes.Newobj, ctorOfU);
        // Store the instance in the local variable; load it
        // again, and load the parameter of genMethod.
        ilg.Emit(OpCodes.Stloc_0); 
        ilg.Emit(OpCodes.Ldloc_0); 
        ilg.Emit(OpCodes.Ldarg_0);
        // In order to store the value in the field of the
        // instance of Sample<U>, it is necessary to have 
        // a FieldInfo representing the field of the 
        // constructed type. Use TypeBuilder.GetField to 
        // obtain this FieldInfo.
        FieldInfo FieldOfU = TypeBuilder.GetField(
            SampleOfU, myField);
        // Store the value in the field. 
        ilg.Emit(OpCodes.Stfld, FieldOfU);
        // Load the instance, load the field value, box it
        // (specifying the type of the type parameter, U), and
        // print it.
        ilg.Emit(OpCodes.Ldloc_0);
        ilg.Emit(OpCodes.Ldfld, FieldOfU);
        ilg.Emit(OpCodes.Box, methodParams[0]);
        MethodInfo writeLineObj = 
            typeof(Console).GetMethod("WriteLine", 
                new Type[] { typeof(object) });
        ilg.EmitCall(OpCodes.Call, writeLineObj, null);
        ilg.Emit(OpCodes.Ret);

        // Emit an entry point method; this must be in a
        // non-generic type.
        TypeBuilder dummy = myModule.DefineType("Dummy", 
            TypeAttributes.Class | TypeAttributes.NotPublic);
        MethodBuilder entryPoint = dummy.DefineMethod("Main", 
            MethodAttributes.Public | MethodAttributes.Static,
            null, null);
        ilg = entryPoint.GetILGenerator();
        // In order to call the static generic method GM, it is
        // necessary to create a constructed type from the 
        // generic type definition for Sample. This can be any
        // constructed type; in this case Sample<int> is used.
        Type SampleOfInt = 
            myType.MakeGenericType( typeof(int) );
        // Next get a MethodInfo representing the static generic
        // method GM on type Sample<int>.
        MethodInfo SampleOfIntGM = TypeBuilder.GetMethod(SampleOfInt, 
            genMethod);
        // Next get a MethodInfo for GM<string>, which is the 
        // instantiation of GM that Main calls.
        MethodInfo GMOfString = 
            SampleOfIntGM.MakeGenericMethod( typeof(string) );
        // Finally, emit the call. Push a string onto
        // the stack, as the argument for the generic method.
        ilg.Emit(OpCodes.Ldstr, "Hello, world!");
        ilg.EmitCall(OpCodes.Call, GMOfString, null);
        ilg.Emit(OpCodes.Ret);

        myType.CreateType();
        dummy.CreateType();
        myAssembly.SetEntryPoint(entryPoint);
        myAssembly.Save(myAsmName.Name + ".exe");

        Console.WriteLine(myAsmName.Name + ".exe has been saved.");
    }
}
Imports System.Reflection
Imports System.Reflection.Emit

' Compare the MSIL in this class to the MSIL
' generated by the Reflection.Emit code in class
' Example.
Public Class Sample(Of T)
    Public Field As T
    Public Shared Sub GM(Of U)(ByVal val As U)
        Dim s As New Sample(Of U)
        s.Field = val
        Console.WriteLine(s.Field)
    
    End Sub
End Class 

Public Class Example
    
    Public Shared Sub Main() 
        Dim myDomain As AppDomain = AppDomain.CurrentDomain
        Dim myAsmName As New AssemblyName("TypeBuilderGetFieldExample")
        Dim myAssembly As AssemblyBuilder = _
            myDomain.DefineDynamicAssembly(myAsmName, _
                AssemblyBuilderAccess.Save)
        Dim myModule As ModuleBuilder = _
            myAssembly.DefineDynamicModule(myAsmName.Name, _
                myAsmName.Name & ".exe")
        
        ' Define the sample type.
        Dim myType As TypeBuilder = myModule.DefineType( _
            "Sample", _
            TypeAttributes.Class Or TypeAttributes.Public)
        
        ' Add a type parameter, making the type generic.
        Dim typeParamNames() As String = { "T" }
        Dim typeParams As GenericTypeParameterBuilder() = _
            myType.DefineGenericParameters(typeParamNames)
        
        ' Define a default constructor. Normally it would 
        ' not be necessary to define the default constructor,
        ' but in this case it is needed for the call to
        ' TypeBuilder.GetConstructor, which gets the default
        ' constructor for the generic type constructed from 
        ' Sample(Of T), in the generic method GM(Of U).
        Dim ctor As ConstructorBuilder = _
            myType.DefineDefaultConstructor( _
                MethodAttributes.PrivateScope Or MethodAttributes.Public _
                Or MethodAttributes.HideBySig Or MethodAttributes.SpecialName _
                Or MethodAttributes.RTSpecialName)
        
        ' Add a field of type T, with the name Field.
        Dim myField As FieldBuilder = myType.DefineField( _
            "Field", typeParams(0), FieldAttributes.Public)
        
        ' Add a method and make it generic, with a type 
        ' parameter named U. Note how similar this is to 
        ' the way Sample is turned into a generic type. The
        ' method has no signature, because the type of its
        ' only parameter is U, which is not yet defined.
        Dim genMethod As MethodBuilder = _
            myType.DefineMethod("GM", _
                MethodAttributes.Public Or MethodAttributes.Static)
        Dim methodParamNames() As String = { "U" }
        Dim methodParams As GenericTypeParameterBuilder() = _
            genMethod.DefineGenericParameters(methodParamNames)

        ' Now add a signature for genMethod, specifying U
        ' as the type of the parameter. There is no return value
        ' and no custom modifiers.
        genMethod.SetSignature(Nothing, Nothing, Nothing, _
            New Type() { methodParams(0) }, Nothing, Nothing)
        
        ' Emit a method body for the generic method.
        Dim ilg As ILGenerator = genMethod.GetILGenerator()
        ' Construct the type Sample(Of U) using MakeGenericType.
        Dim SampleOfU As Type = _
            myType.MakeGenericType(methodParams(0))
        ' Create a local variable to store the instance of
        ' Sample(Of U).
        ilg.DeclareLocal(SampleOfU)
        ' Call the default constructor. Note that it is 
        ' necessary to have the default constructor for the
        ' constructed generic type Sample(Of U); use the 
        ' TypeBuilder.GetConstructor method to obtain this 
        ' constructor.
        Dim ctorOfU As ConstructorInfo = _
            TypeBuilder.GetConstructor(SampleOfU, ctor)
        ilg.Emit(OpCodes.Newobj, ctorOfU)
        ' Store the instance in the local variable; load it
        ' again, and load the parameter of genMethod.
        ilg.Emit(OpCodes.Stloc_0)
        ilg.Emit(OpCodes.Ldloc_0)
        ilg.Emit(OpCodes.Ldarg_0)
        ' In order to store the value in the field of the
        ' instance of Sample(Of U), it is necessary to have 
        ' a FieldInfo representing the field of the 
        ' constructed type. Use TypeBuilder.GetField to 
        ' obtain this FieldInfo.
        Dim FieldOfU As FieldInfo = _
            TypeBuilder.GetField(SampleOfU, myField)
        ' Store the value in the field. 
        ilg.Emit(OpCodes.Stfld, FieldOfU)
        ' Load the instance, load the field value, box it
        ' (specifying the type of the type parameter, U), 
        ' and print it.
        ilg.Emit(OpCodes.Ldloc_0)
        ilg.Emit(OpCodes.Ldfld, FieldOfU)
        ilg.Emit(OpCodes.Box, methodParams(0))
        Dim writeLineObj As MethodInfo = _
            GetType(Console).GetMethod("WriteLine", _
                New Type() {GetType(Object)})
        ilg.EmitCall(OpCodes.Call, writeLineObj, Nothing)
        ilg.Emit(OpCodes.Ret)
        
        ' Emit an entry point method; this must be in a
        ' non-generic type.
        Dim dummy As TypeBuilder = _
            myModule.DefineType("Dummy", _
                TypeAttributes.Class Or TypeAttributes.NotPublic)
        Dim entryPoint As MethodBuilder = _
            dummy.DefineMethod("Main", _
                MethodAttributes.Public Or MethodAttributes.Static, _
                Nothing, Nothing)
        ilg = entryPoint.GetILGenerator()
        ' In order to call the static generic method GM, it is
        ' necessary to create a constructed type from the 
        ' generic type definition for Sample. This can be ANY
        ' constructed type; in this case Sample(Of Integer)
        ' is used.
        Dim SampleOfInt As Type = _
            myType.MakeGenericType(GetType(Integer))
        ' Next get a MethodInfo representing the static generic
        ' method GM on type Sample(Of Integer).
        Dim SampleOfIntGM As MethodInfo = _
            TypeBuilder.GetMethod(SampleOfInt, genMethod)
        ' Next get a MethodInfo for GM(Of String), which is the 
        ' instantiation of generic method GM that is called
        ' by Sub Main.
        Dim GMOfString As MethodInfo = _
            SampleOfIntGM.MakeGenericMethod(GetType(String))
        ' Finally, emit the call. Push a string onto
        ' the stack, as the argument for the generic method.
        ilg.Emit(OpCodes.Ldstr, "Hello, world!")
        ilg.EmitCall(OpCodes.Call, GMOfString, Nothing)
        ilg.Emit(OpCodes.Ret)
        
        myType.CreateType()
        dummy.CreateType()
        myAssembly.SetEntryPoint(entryPoint)
        myAssembly.Save(myAsmName.Name & ".exe")
        
        Console.WriteLine(myAsmName.Name & ".exe has been saved.")
    
    End Sub 
End Class 

注解

方法提供了一种方法来ConstructorInfo获取表示构造泛型类型(其泛型类型TypeBuilder定义由对象表示)的构造函数的对象。 GetConstructorThe GetConstructor method provides a way to get a ConstructorInfo object that represents a constructor of a constructed generic type whose generic type definition is represented by a TypeBuilder object.

例如TypeBuilder ,假设你有一个对象,该对象表示语法中C#的类型G(Of T) G<T> (在中generic <T> ref class G为C++Visual Basic)和ConstructorBuilder一个对象(表示的G<T>构造函数).For example, suppose you have a TypeBuilder object that represents the type G<T> in C# syntax (G(Of T) in Visual Basic, generic <T> ref class G in C++) and a ConstructorBuilder object that represents a constructor of G<T>. 假设有一个具有类型参数U的泛型方法,该方法可创建构造类型G<U>的实例。 G<T>Suppose that G<T> has a generic method with type parameter U that creates an instance of the constructed type G<U>. 为了发出代码以创建构造类型的实例,需要一个ConstructorInfo表示此构造类型的构造函数的对象(即,创建G<U>实例的对象)。In order to emit the code to create an instance of the constructed type, you need a ConstructorInfo object that represents the constructor of this constructed type - in other words, that creates an instance of G<U>. 为此MakeGenericType ,请先对TypeBuilder对象调用方法,并指定GenericTypeParameterBuilder表示U为类型参数的对象。To do this, first call the MakeGenericType method on the TypeBuilder object, specifying the GenericTypeParameterBuilder object that represents U as the type argument. 然后GetConstructor调用constructor方法, type MakeGenericType 并将ConstructorBuilder方法的返回值作为参数,并将表示的构造函数的对象作为参数。G<U>Then call the GetConstructor method with the return value of the MakeGenericType method as parameter type and the ConstructorBuilder object that represents the constructor of G<U> as parameter constructor. 返回值是发出函数ConstructorInfo调用所需的对象。The return value is the ConstructorInfo object you need to emit the function call. 此代码示例演示了这种情况。The code example demonstrates this scenario.

适用于