MethodBuilder.DefineGenericParameters(String[]) Methode

Definition

Namespace:

System.Reflection.Emit

Assembly:

System.Reflection.Emit.dll

Quelle:

MethodBuilder.cs

Legt die Anzahl von generischen Typparametern für die aktuelle Methode fest, gibt deren Namen an und gibt ein Array von GenericTypeParameterBuilder-Objekten zurück, das dazu verwendet werden kann, deren Einschränkungen zu definieren.

public:
 cli::array <System::Reflection::Emit::GenericTypeParameterBuilder ^> ^ DefineGenericParameters(... cli::array <System::String ^> ^ names);

public System.Reflection.Emit.GenericTypeParameterBuilder[] DefineGenericParameters (params string[] names);

member this.DefineGenericParameters : string[] -> System.Reflection.Emit.GenericTypeParameterBuilder[]

Public Function DefineGenericParameters (ParamArray names As String()) As GenericTypeParameterBuilder()

Parameter

names

String[]

Ein Array von Zeichenfolgen, die die Namen der generischen Typparameter darstellen.

Gibt zurück

GenericTypeParameterBuilder[]

Ein Array von GenericTypeParameterBuilder-Objekten, die die Typparameter der generischen Methode darstellen.

Ausnahmen

InvalidOperationException

Es wurden bereits generische Typparameter für diese Methode definiert.

- oder -

Die Methode wurde bereits abgeschlossen.

- oder -

Die SetImplementationFlags(MethodImplAttributes)-Methode wurde für die aktuelle Methode aufgerufen.

ArgumentNullException

names ist null.

- oder -

Ein Element von names ist null.

ArgumentException

names ist ein leeres Array.

Beispiele

Im folgenden Codebeispiel wird ein dynamischer Typ erstellt, DemoTypeder die dynamische generische Methode DemoMethodenthält. Diese Methode verfügt über zwei generische Typparameter, von denen einer als Parameter und der andere als Rückgabetyp verwendet wird.

Bei der Codeausführung wird die dynamische Assembly als DemoGenericMethod1.dll gespeichert. Sie kann mit Ildasm.exe (IL-Disassembler) untersucht werden.

Hinweis

In diesem Codebeispiel wird ein einfacher Methodentext generiert, der lediglich einen NULL-Verweis zurückgibt. Ein Codebeispiel mit einem vollständig entwickelten Methodentext, der generische Typen erstellt und verwendet, finden Sie unter How to: Define a Generic Method with Reflection Emit.

using namespace System;
using namespace System::Reflection;
using namespace System::Reflection::Emit;

public ref class GenericReflectionSample
{
};

int main()
{
    // Creating a dynamic assembly requires an AssemblyName
    // object, and the current application domain.
    //
    AssemblyName^ asmName =
        gcnew AssemblyName("EmittedAssembly");
    AppDomain^ domain = AppDomain::CurrentDomain;
    AssemblyBuilder^ sampleAssemblyBuilder =
        domain->DefineDynamicAssembly(asmName,
        AssemblyBuilderAccess::RunAndSave);

    // Define the module that contains the code. For an
    // assembly with one module, the module name is the
    // assembly name plus a file extension.
    ModuleBuilder^ sampleModuleBuilder =
        sampleAssemblyBuilder->DefineDynamicModule(asmName->Name,
        asmName->Name + ".dll");

    TypeBuilder^ sampleTypeBuilder =
        sampleModuleBuilder->DefineType("SampleType",
        TypeAttributes::Public | TypeAttributes::Abstract);

    // Define a Shared, Public method with standard calling
    // conventions. Do not specify the parameter types or the
    // return type, because type parameters will be used for
    // those types, and the type parameters have not been
    // defined yet.
    MethodBuilder^ sampleMethodBuilder =
        sampleTypeBuilder->DefineMethod("SampleMethod",
        MethodAttributes::Public | MethodAttributes::Static);

    // Defining generic parameters for the method makes it a
    // generic method. By convention, type parameters are
    // single alphabetic characters. T and U are used here.
    //
    array<String^>^ genericTypeNames = {"T", "U"};
    array<GenericTypeParameterBuilder^>^ genericTypes =
        sampleMethodBuilder->DefineGenericParameters(
        genericTypeNames);

    // Use the IsGenericMethod property to find out if a
    // dynamic method is generic, and IsGenericMethodDefinition
    // to find out if it defines a generic method.
    Console::WriteLine("Is SampleMethod generic? {0}",
        sampleMethodBuilder->IsGenericMethod);
    Console::WriteLine(
        "Is SampleMethod a generic method definition? {0}",
        sampleMethodBuilder->IsGenericMethodDefinition);

    // Set parameter types for the method. The method takes
    // one parameter, and its type is specified by the first
    // type parameter, T.
    array<Type^>^ parameterTypes = {genericTypes[0]};
    sampleMethodBuilder->SetParameters(parameterTypes);

    // Set the return type for the method. The return type is
    // specified by the second type parameter, U.
    sampleMethodBuilder->SetReturnType(genericTypes[1]);

    // Generate a code body for the method. The method doesn't
    // do anything except return null.
    //
    ILGenerator^ ilgen = sampleMethodBuilder->GetILGenerator();
    ilgen->Emit(OpCodes::Ldnull);
    ilgen->Emit(OpCodes::Ret);

    // Complete the type.
    Type^ sampleType = sampleTypeBuilder->CreateType();

    // To bind types to a dynamic generic method, you must
    // first call the GetMethod method on the completed type.
    // You can then define an array of types, and bind them
    // to the method.
    MethodInfo^ sampleMethodInfo = sampleType->GetMethod("SampleMethod");
    array<Type^>^ boundParameters =
        {String::typeid, GenericReflectionSample::typeid};
    MethodInfo^ boundMethodInfo =
        sampleMethodInfo->MakeGenericMethod(boundParameters);
    // Display a string representing the bound method.
    Console::WriteLine(boundMethodInfo);

    // Save the assembly, so it can be examined with Ildasm.exe.
    sampleAssemblyBuilder->Save(asmName->Name + ".dll");
}

/* This code example produces the following output:
Is SampleMethod generic? True
Is SampleMethod a generic method definition? True
GenericReflectionSample SampleMethod[String,GenericReflectionSample](System.String)
*/

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

class DemoMethodBuilder
{

    public static void Main()
    {
        // Creating a dynamic assembly requires an AssemblyName
        // object, and the current application domain.
        //
        AssemblyName asmName =
            new AssemblyName("DemoMethodBuilder1");
        AppDomain domain = AppDomain.CurrentDomain;
        AssemblyBuilder demoAssembly =
            domain.DefineDynamicAssembly(
                asmName,
                AssemblyBuilderAccess.RunAndSave
            );

        // Define the module that contains the code. For an
        // assembly with one module, the module name is the
        // assembly name plus a file extension.
        ModuleBuilder demoModule =
            demoAssembly.DefineDynamicModule(
                asmName.Name,
                asmName.Name + ".dll"
            );

        TypeBuilder demoType = demoModule.DefineType(
            "DemoType",
            TypeAttributes.Public | TypeAttributes.Abstract
        );

        // Define a Shared, Public method with standard calling
        // conventions. Do not specify the parameter types or the
        // return type, because type parameters will be used for
        // those types, and the type parameters have not been
        // defined yet.
        MethodBuilder demoMethod = demoType.DefineMethod(
            "DemoMethod",
            MethodAttributes.Public | MethodAttributes.Static
        );

        // Defining generic parameters for the method makes it a
        // generic method. By convention, type parameters are
        // single alphabetic characters. T and U are used here.
        //
        string[] typeParamNames = {"T", "U"};
        GenericTypeParameterBuilder[] typeParameters =
            demoMethod.DefineGenericParameters(typeParamNames);

        // The second type parameter is constrained to be a
        // reference type.
        typeParameters[1].SetGenericParameterAttributes(
            GenericParameterAttributes.ReferenceTypeConstraint);

        // Use the IsGenericMethod property to find out if a
        // dynamic method is generic, and IsGenericMethodDefinition
        // to find out if it defines a generic method.
        Console.WriteLine("Is DemoMethod generic? {0}",
            demoMethod.IsGenericMethod);
        Console.WriteLine("Is DemoMethod a generic method definition? {0}",
            demoMethod.IsGenericMethodDefinition);

        // Set parameter types for the method. The method takes
        // one parameter, and its type is specified by the first
        // type parameter, T.
        Type[] parms = {typeParameters[0]};
        demoMethod.SetParameters(parms);

        // Set the return type for the method. The return type is
        // specified by the second type parameter, U.
        demoMethod.SetReturnType(typeParameters[1]);

        // Generate a code body for the method. The method doesn't
        // do anything except return null.
        //
        ILGenerator ilgen = demoMethod.GetILGenerator();
        ilgen.Emit(OpCodes.Ldnull);
        ilgen.Emit(OpCodes.Ret);

        // Complete the type.
        Type dt = demoType.CreateType();

        // To bind types to a dynamic generic method, you must
        // first call the GetMethod method on the completed type.
        // You can then define an array of types, and bind them
        // to the method.
        MethodInfo m = dt.GetMethod("DemoMethod");
        Type[] typeArgs = {typeof(string), typeof(DemoMethodBuilder)};
        MethodInfo bound = m.MakeGenericMethod(typeArgs);
        // Display a string representing the bound method.
        Console.WriteLine(bound);

        // Save the assembly, so it can be examined with Ildasm.exe.
        demoAssembly.Save(asmName.Name + ".dll");
    }
}

/* This code example produces the following output:
Is DemoMethod generic? True
Is DemoMethod a generic method definition? True
DemoMethodBuilder DemoMethod[String,DemoMethodBuilder](System.String)
*/

Imports System.Reflection
Imports System.Reflection.Emit

Class DemoMethodBuilder
   
    Public Shared Sub Main()
        ' Creating a dynamic assembly requires an AssemblyName
        ' object, and the current application domain.
        '
        Dim asmName As New AssemblyName("DemoMethodBuilder1")
        Dim domain As AppDomain = AppDomain.CurrentDomain
        Dim demoAssembly As AssemblyBuilder = _
            domain.DefineDynamicAssembly(asmName, _
                AssemblyBuilderAccess.RunAndSave)

        ' Define the module that contains the code. For an 
        ' assembly with one module, the module name is the 
        ' assembly name plus a file extension.
        Dim demoModule As ModuleBuilder = _
            demoAssembly.DefineDynamicModule( _
                asmName.Name, _
                asmName.Name & ".dll")
      
        Dim demoType As TypeBuilder = demoModule.DefineType( _
            "DemoType", _
            TypeAttributes.Public Or TypeAttributes.Abstract)

        ' Define a Shared, Public method with standard calling
        ' conventions. Do not specify the parameter types or the
        ' return type, because type parameters will be used for 
        ' those types, and the type parameters have not been
        ' defined yet.
        Dim demoMethod As MethodBuilder = _
            demoType.DefineMethod("DemoMethod", _
                MethodAttributes.Public Or MethodAttributes.Static)

        ' Defining generic parameters for the method makes it a
        ' generic method. By convention, type parameters are 
        ' single alphabetic characters. T and U are used here.
        '
        Dim typeParamNames() As String = {"T", "U"}
        Dim typeParameters() As GenericTypeParameterBuilder = _
            demoMethod.DefineGenericParameters(typeParamNames)

        ' The second type parameter is constrained to be a 
        ' reference type.
        typeParameters(1).SetGenericParameterAttributes( _
            GenericParameterAttributes.ReferenceTypeConstraint)

        ' Use the IsGenericMethod property to find out if a
        ' dynamic method is generic, and IsGenericMethodDefinition
        ' to find out if it defines a generic method.
        Console.WriteLine("Is DemoMethod generic? {0}", _
            demoMethod.IsGenericMethod)
        Console.WriteLine("Is DemoMethod a generic method definition? {0}", _
            demoMethod.IsGenericMethodDefinition)

        ' Set parameter types for the method. The method takes
        ' one parameter, and its type is specified by the first
        ' type parameter, T.
        Dim params() As Type = {typeParameters(0)}
        demoMethod.SetParameters(params)

        ' Set the return type for the method. The return type is
        ' specified by the second type parameter, U.
        demoMethod.SetReturnType(typeParameters(1))

        ' Generate a code body for the method. The method doesn't
        ' do anything except return Nothing.
        '
        Dim ilgen As ILGenerator = demoMethod.GetILGenerator()
        ilgen.Emit(OpCodes.Ldnull)
        ilgen.Emit(OpCodes.Ret)

        ' Complete the type.
        Dim dt As Type = demoType.CreateType()

        ' To bind types to a dynamic generic method, you must 
        ' first call the GetMethod method on the completed type.
        ' You can then define an array of types, and bind them
        ' to the method.
        Dim m As MethodInfo = dt.GetMethod("DemoMethod")
        Dim typeArgs() As Type = _
            {GetType(String), GetType(DemoMethodBuilder)}
        Dim bound As MethodInfo = m.MakeGenericMethod(typeArgs)
        ' Display a string representing the bound method.
        Console.WriteLine(bound)

        ' Save the assembly, so it can be examined with Ildasm.exe.
        demoAssembly.Save(asmName.Name & ".dll")
    End Sub  
End Class 

' This code example produces the following output:
'Is DemoMethod generic? True
'Is DemoMethod a generic method definition? True
'DemoMethodBuilder DemoMethod[String,DemoMethodBuilder](System.String)

Hinweise

Durch Aufrufen der DefineGenericParameters -Methode wird die aktuelle Methode generisch. Es gibt keine Möglichkeit, diese Änderung rückgängig zu machen. Das zweite Aufrufen dieser Methode führt zu einem InvalidOperationException.

Die Typparameter der generischen Methode können später mithilfe der GetGenericArguments -Methode abgerufen werden.

Gemäß der Konvention ist ein Typparametername ein einzelner Großbuchstaben.

Weitere Informationen finden Sie unter MethodBase.IsGenericMethod und MethodInfo.GetGenericMethodDefinition. Informationen zu generischen Typen finden Sie unter Type.IsGenericType.

Weitere Informationen

• MethodInfo
• IsGenericType
• DefineMethod
• Vorgehensweise: Definieren einer generischen Methode mit Reflektionsausgabe