TypeBuilder.DefineMethodOverride(MethodInfo, MethodInfo) 方法

參考

定義

命名空間:: System.Reflection.Emit

組件:: System.Reflection.Emit.dll

組件:: mscorlib.dll

組件:: netstandard.dll

來源:: TypeBuilder.cs

來源:: TypeBuilder.cs

來源:: TypeBuilder.cs

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

指定實作給定方法宣告的給定方法主體，可能會使用其他名稱。

public:
 void DefineMethodOverride(System::Reflection::MethodInfo ^ methodInfoBody, System::Reflection::MethodInfo ^ methodInfoDeclaration);

public void DefineMethodOverride (System.Reflection.MethodInfo methodInfoBody, System.Reflection.MethodInfo methodInfoDeclaration);

member this.DefineMethodOverride : System.Reflection.MethodInfo * System.Reflection.MethodInfo -> unit

Public Sub DefineMethodOverride (methodInfoBody As MethodInfo, methodInfoDeclaration As MethodInfo)

參數

methodInfoBody: MethodInfo

要使用的方法主體。應該是 MethodBuilder 物件。

methodInfoDeclaration: MethodInfo

要使用其宣告的方法。

例外狀況

ArgumentException

methodInfoBody 不屬於這個類別。

ArgumentNullException

methodInfoBody 或 methodInfoDeclaration 為 null。

InvalidOperationException

先前使用 CreateType() 建立的類型。

-或-

methodInfoBody 的宣告類型不是 TypeBuilder 所表示的類型。

範例

下列程式碼範例包含具有方法的介面 I 、實作介面的基類 A ，以及覆寫基類實 M() 作的衍生類別 C ，也提供個別的明確實作 I.M() 。 M()

程式 main() 代碼範例的方法示範如何發出衍生類別 C 。的覆寫 A.M() 只是透過發出具有相同簽章的方法 M() 來完成。不過，若要提供的個別實 I.M() 作，您必須定義方法主體，然後使用 DefineMethodOverride 方法來建立該方法主體與 MethodInfo 表示的 I.M() 關聯。方法主體的名稱並不重要。

程式碼範例會建立發出類別的實例。它會取得 MethodInfo 的 I.M() 物件，並用它來叫用發出的類別明確介面實作。然後，它會取得 MethodInfo 的 A.M() 物件，並用它來叫用發出之類別的該方法覆寫。

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

public interface class I 
{
    void M();
};

public ref class A 
{
public:
    virtual void M() { Console::WriteLine("In method A.M"); }
};

// The object of this code example is to emit code equivalent to
// the following C++ code:
//
public ref class C : A, I 
{
public:
    virtual void M() override 
    { 
        Console::WriteLine("Overriding A.M from C.M"); 
    }

private:
    // In order to provide a different implementation from C.M when 
    // emitting the following explicit interface implementation, 
    // it is necessary to use a MethodImpl.
    //
    virtual void IM() sealed = I::M 
    {
        Console::WriteLine("The I::M implementation of C");
    }
};

void main() 
{
    String^ name = "DefineMethodOverrideExample";
    AssemblyName^ asmName = gcnew AssemblyName(name);
    AssemblyBuilder^ ab = 
        AppDomain::CurrentDomain->DefineDynamicAssembly(
            asmName, AssemblyBuilderAccess::RunAndSave);
    ModuleBuilder^ mb = ab->DefineDynamicModule(name, name + ".dll");

    TypeBuilder^ tb = 
        mb->DefineType("C", TypeAttributes::Public, A::typeid);
    tb->AddInterfaceImplementation(I::typeid);

    // Build the method body for the explicit interface 
    // implementation. The name used for the method body 
    // can be anything. Here, it is the name of the method,
    // qualified by the interface name.
    //
    MethodBuilder^ mbIM = tb->DefineMethod("I.M", 
        MethodAttributes::Private | MethodAttributes::HideBySig |
            MethodAttributes::NewSlot | MethodAttributes::Virtual | 
            MethodAttributes::Final,
        nullptr,
        Type::EmptyTypes);
    ILGenerator^ il = mbIM->GetILGenerator();
    il->Emit(OpCodes::Ldstr, "The I.M implementation of C");
    il->Emit(OpCodes::Call, Console::typeid->GetMethod("WriteLine", 
        gcnew array<Type^> { String::typeid }));
    il->Emit(OpCodes::Ret);

    // DefineMethodOverride is used to associate the method 
    // body with the interface method that is being implemented.
    //
    tb->DefineMethodOverride(mbIM, I::typeid->GetMethod("M"));

    MethodBuilder^ mbM = tb->DefineMethod("M", 
        MethodAttributes::Public | MethodAttributes::ReuseSlot | 
            MethodAttributes::Virtual | MethodAttributes::HideBySig, 
        nullptr, 
        Type::EmptyTypes);
    il = mbM->GetILGenerator();
    il->Emit(OpCodes::Ldstr, "Overriding A.M from C.M");
    il->Emit(OpCodes::Call, Console::typeid->GetMethod("WriteLine", 
        gcnew array<Type^> { String::typeid }));
    il->Emit(OpCodes::Ret);

    Type^ tc = tb->CreateType();

    // Save the emitted assembly, to examine with Ildasm.exe.
    ab->Save(name + ".dll");

    Object^ test = Activator::CreateInstance(tc);

    MethodInfo^ mi = I::typeid->GetMethod("M");
    mi->Invoke(test, nullptr);

    mi = A::typeid->GetMethod("M");
    mi->Invoke(test, nullptr);
}

/* This code example produces the following output:

The I.M implementation of C
Overriding A.M from C.M
 */

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

public interface I
{
    void M();
}

public class A
{
    public virtual void M() { Console.WriteLine("In method A.M"); }
}

// The object of this code example is to emit code equivalent to
// the following C# code:
//
public class C : A, I
{
    public override void M()
    {
        Console.WriteLine("Overriding A.M from C.M");
    }

    // In order to provide a different implementation from C.M when
    // emitting the following explicit interface implementation,
    // it is necessary to use a MethodImpl.
    //
    void I.M()
    {
        Console.WriteLine("The I.M implementation of C");
    }
}

class Test
{
    static void Main()
    {
        string name = "DefineMethodOverrideExample";
        AssemblyName asmName = new AssemblyName(name);
        AssemblyBuilder ab =
            AppDomain.CurrentDomain.DefineDynamicAssembly(
                asmName, AssemblyBuilderAccess.RunAndSave);
        ModuleBuilder mb = ab.DefineDynamicModule(name, name + ".dll");

        TypeBuilder tb =
            mb.DefineType("C", TypeAttributes.Public, typeof(A));
        tb.AddInterfaceImplementation(typeof(I));

        // Build the method body for the explicit interface
        // implementation. The name used for the method body
        // can be anything. Here, it is the name of the method,
        // qualified by the interface name.
        //
        MethodBuilder mbIM = tb.DefineMethod("I.M",
            MethodAttributes.Private | MethodAttributes.HideBySig |
                MethodAttributes.NewSlot | MethodAttributes.Virtual |
                MethodAttributes.Final,
            null,
            Type.EmptyTypes);
        ILGenerator il = mbIM.GetILGenerator();
        il.Emit(OpCodes.Ldstr, "The I.M implementation of C");
        il.Emit(OpCodes.Call, typeof(Console).GetMethod("WriteLine",
            new Type[] { typeof(string) }));
        il.Emit(OpCodes.Ret);

        // DefineMethodOverride is used to associate the method
        // body with the interface method that is being implemented.
        //
        tb.DefineMethodOverride(mbIM, typeof(I).GetMethod("M"));

        MethodBuilder mbM = tb.DefineMethod("M",
            MethodAttributes.Public | MethodAttributes.ReuseSlot |
                MethodAttributes.Virtual | MethodAttributes.HideBySig,
            null,
            Type.EmptyTypes);
        il = mbM.GetILGenerator();
        il.Emit(OpCodes.Ldstr, "Overriding A.M from C.M");
        il.Emit(OpCodes.Call, typeof(Console).GetMethod("WriteLine",
            new Type[] { typeof(string) }));
        il.Emit(OpCodes.Ret);

        Type tc = tb.CreateType();

        // Save the emitted assembly, to examine with Ildasm.exe.
        ab.Save(name + ".dll");

        Object test = Activator.CreateInstance(tc);

        MethodInfo mi = typeof(I).GetMethod("M");
        mi.Invoke(test, null);

        mi = typeof(A).GetMethod("M");
        mi.Invoke(test, null);
    }
}

/* This code example produces the following output:

The I.M implementation of C
Overriding A.M from C.M
 */

Imports System.Reflection
Imports System.Reflection.Emit

Public Interface I
    Sub M() 
End Interface

Public Class A
    Public Overridable Sub M() 
        Console.WriteLine("In method A.M")
    End Sub
End Class

' The object of this code example is to emit code equivalent to
' the following C# code:
'
Public Class C
    Inherits A
    Implements I
    
    Public Overrides Sub M() 
        Console.WriteLine("Overriding A.M from C.M")
    End Sub
    
    ' In order to provide a different implementation from C.M when 
    ' emitting the following explicit interface implementation, 
    ' it is necessary to use a MethodImpl.
    '
    Private Sub IM() Implements I.M
        Console.WriteLine("The I.M implementation of C")
    End Sub
End Class

Class Test
    
    Shared Sub Main() 

        Dim name As String = "DefineMethodOverrideExample"
        Dim asmName As New AssemblyName(name)
        Dim ab As AssemblyBuilder = _
            AppDomain.CurrentDomain.DefineDynamicAssembly( _
                asmName, AssemblyBuilderAccess.RunAndSave)
        Dim mb As ModuleBuilder = _
            ab.DefineDynamicModule(name, name & ".dll")
        
        Dim tb As TypeBuilder = _
            mb.DefineType("C", TypeAttributes.Public, GetType(A))
        tb.AddInterfaceImplementation(GetType(I))
        
        ' Build the method body for the explicit interface 
        ' implementation. The name used for the method body 
        ' can be anything. Here, it is the name of the method,
        ' qualified by the interface name.
        '
        Dim mbIM As MethodBuilder = _
            tb.DefineMethod("I.M", _
            MethodAttributes.Private Or MethodAttributes.HideBySig Or _
                MethodAttributes.NewSlot Or MethodAttributes.Virtual Or _
                MethodAttributes.Final, _
            Nothing, _
            Type.EmptyTypes)
        Dim il As ILGenerator = mbIM.GetILGenerator()
        il.Emit(OpCodes.Ldstr, "The I.M implementation of C")
        il.Emit(OpCodes.Call, GetType(Console).GetMethod("WriteLine", _
            New Type() {GetType(String)}))
        il.Emit(OpCodes.Ret)
        
        ' DefineMethodOverride is used to associate the method 
        ' body with the interface method that is being implemented.
        '
        tb.DefineMethodOverride(mbIM, GetType(I).GetMethod("M"))
        
        Dim mbM As MethodBuilder = tb.DefineMethod("M", _
            MethodAttributes.Public Or MethodAttributes.ReuseSlot Or _
                MethodAttributes.Virtual Or MethodAttributes.HideBySig, _
            Nothing, _
            Type.EmptyTypes)
        il = mbM.GetILGenerator()
        il.Emit(OpCodes.Ldstr, "Overriding A.M from C.M")
        il.Emit(OpCodes.Call, GetType(Console).GetMethod("WriteLine", _
            New Type() {GetType(String)}))
        il.Emit(OpCodes.Ret)
        
        Dim tc As Type = tb.CreateType()
        
        ' Save the emitted assembly, to examine with Ildasm.exe.
        ab.Save(name & ".dll")
        
        Dim test As Object = Activator.CreateInstance(tc)
        
        Dim mi As MethodInfo = GetType(I).GetMethod("M")
        mi.Invoke(test, Nothing)
        
        mi = GetType(A).GetMethod("M")
        mi.Invoke(test, Nothing)
    
    End Sub
End Class

' This code example produces the following output:
'
'The I.M implementation of C
'Overriding A.M from C.M
'

備註

請勿使用這個方法來發出方法覆寫或介面實作。若要覆寫基類的方法，或實作介面的方法，只要發出具有相同名稱和簽章的方法，就像要覆寫或實作的方法一樣，如程式碼範例所示。

當方法主體和方法宣告具有不同的名稱時，就會 DefineMethodOverride 使用方法。例如，類別可能會覆寫基類方法，同時也為具有相同名稱的介面成員提供個別的實作，如程式碼範例所示。

DefineMethodOverride 會 methodimpl 定義，其中包含一組中繼資料權杖。一個權杖指向實作，另一個權杖指向主體所實作的宣告。本文必須定義于方法 impl 所定義的型別上，而且本文必須是 Visual Basic) 中的虛擬 (Overridable 。宣告可以針對型別所實作的介面、衍生類別上的方法，或型別中定義的方法進行。如果宣告只在介面上，則會改變為介面定義的位置。如果宣告是在基底類型上對方法進行，則會覆寫方法的位置，而且也會取代覆寫方法的任何重複專案。覆寫的方法不能是宣告的實際方法。如果方法位於相同類型上，則會取代位置，並覆寫所取代方法的任何重複專案。

注意

如需方法 impls 的詳細資訊，請參閱 MethodImplECMA C# 和 Common Language Infrastructure Standard 和 Standard ECMA-335 - Common Language Infrastructure (CLI) 中的 ECMA 分割區 II 元資料檔案中。

重要

DefineMethodOverride呼叫方法之後，就無法變更的某些 methodInfoBody 功能。例如，您無法使用 SetGenericParameterAttributes 方法，將屬性套用至的 methodInfoBody 泛型型別參數。如果您必須使用 DefineMethodOverride 方法，請在已定義的所有特性 methodInfoBody 之後執行此動作。

適用於

TypeBuilder.DefineMethodOverride(MethodInfo, MethodInfo) 方法

定義

參數

例外狀況

範例

備註

適用於

意見反應

其他資源