MethodBase.IsHideBySig Propriété
Définition
Important
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Obtient une valeur indiquant si seul un membre du même type, doté d'une signature identique, est caché dans la classe dérivée.
public:
property bool IsHideBySig { bool get(); };public bool IsHideBySig { get; }member this.IsHideBySig : boolPublic ReadOnly Property IsHideBySig As BooleanValeur de propriété
true si le membre est caché par signature ; sinon, false.
Implémente
Exemples
L’exemple de code suivant contient une classe de base avec une méthode surchargée et une classe dérivée qui masque l’une des surcharges. Dans la version Visual Basic de l’exemple de code, la IsHideBySig propriété retourne false pour le membre dans la classe dérivée. Dans la version C# de l’exemple de code, la propriété retourne true pour le membre de la classe dérivée.
using namespace System;
using namespace System::Reflection;
// The base class Parent contains an overloaded method PrintCall.
//
public ref class Parent
{
public:
virtual void PrintCall()
{
Console::WriteLine("Parent's PrintCall()");
}
public:
virtual void PrintCall(int x)
{
Console::WriteLine("Parent's PrintCall({0})", x);
}
};
// The derived class Child hides one overload of the inherited
// method PrintCall.
//
public ref class Child : public Parent
{
public:
void PrintCall(int i) new
{
Console::WriteLine("Child's PrintCall({0})", i);
}
};
int main()
{
Child^ childInstance = gcnew Child();
// In C#, the method in the derived class hides by name and by
// signature, so the overload in the derived class hides only one
// of the overloads in the base class.
//
Console::WriteLine("------ List the overloads of PrintCall in the " +
"derived class Child ------");
Type^ t = childInstance->GetType();
for each(MethodInfo^ minfo in t->GetMethods())
{
if (minfo->Name == "PrintCall")
{
Console::WriteLine("Overload of PrintCall: {0}" +
" IsHideBySig = {1}, DeclaringType = {2}",
minfo, minfo->IsHideBySig, minfo->DeclaringType);
}
}
// The method PrintCall in the derived class hides one overload of the
// method in Parent. Contrast this with Visual Basic, which hides by
// name instead of by name and signature. In Visual Basic, the
// parameterless overload of PrintCall would be unavailable from Child.
//
Console::WriteLine(
"------ Call the overloads of PrintCall available in Child ------");
childInstance->PrintCall();
childInstance->PrintCall(42);
// If Child is cast to the base type Parent, both overloads of the
// shadowed method can be called.
//
Console::WriteLine(
"------ Call the shadowed overloads of PrintCall ------");
Parent^ parentInstance = childInstance;
parentInstance->PrintCall();
parentInstance->PrintCall(42);
}
/* This code example produces the following output:
------ List the overloads of PrintCall in the derived class Child ------
Overload of PrintCall: Void PrintCall(Int32) IsHideBySig = True, DeclaringType = Child
Overload of PrintCall: Void PrintCall() IsHideBySig = True, DeclaringType = Parent
Overload of PrintCall: Void PrintCall(Int32) IsHideBySig = True, DeclaringType = Parent
------ Call the overloads of PrintCall available in Child ------
Parent's PrintCall()
Child's PrintCall(42)
------ Call the shadowed overloads of PrintCall ------
Parent's PrintCall()
Parent's PrintCall(42)
*/
using System;
using System.Reflection;
// The base class B contains an overloaded method M.
//
public class B
{
public virtual void M()
{
Console.WriteLine("B's M()");
}
public virtual void M(int x)
{
Console.WriteLine("B's M({0})", x);
}
}
// The derived class D hides one overload of the inherited
// method M.
//
public class D:
B
{
new public void M(int i)
{
Console.WriteLine("D's M({0})", i);
}
}
public class Test
{
public static void Main()
{
D dinst = new D();
// In C#, the method in the derived class hides by name and by
// signature, so the overload in the derived class hides only one
// of the overloads in the base class.
//
Console.WriteLine("------ List the overloads of M in the derived class D ------");
Type t = dinst.GetType();
foreach( MethodInfo minfo in t.GetMethods() )
{
if (minfo.Name=="M") {Console.WriteLine("Overload of M: {0} IsHideBySig = {1}, DeclaringType = {2}", minfo, minfo.IsHideBySig, minfo.DeclaringType);}
}
// The method M in the derived class hides one overload of the
// method in B. Contrast this with Visual Basic, which hides by
// name instead of by name and signature. In Visual Basic, the
// parameterless overload of M would be unavailable from D.
//
Console.WriteLine("------ Call the overloads of M available in D ------");
dinst.M();
dinst.M(42);
// If D is cast to the base type B, both overloads of the
// shadowed method can be called.
//
Console.WriteLine("------ Call the shadowed overloads of M ------");
B binst = dinst;
binst.M();
binst.M(42);
} //Main
} //Test
/* This code example produces the following output:
------ List the overloads of M in the derived class D ------
Overload of M: Void M(Int32) IsHideBySig = True, DeclaringType = B
Overload of M: Void M() IsHideBySig = True, DeclaringType = B
Overload of M: Void M(Int32) IsHideBySig = True, DeclaringType = D
------ Call the overloads of M available in D ------
B's M()
D's M(42)
------ Call the shadowed overloads of M ------
B's M()
B's M(42)
*/
Imports System.Reflection
' The base class B contains an overloaded method M.
'
Public Class B
Public Overridable Sub M()
Console.WriteLine("B's M()")
End Sub
Public Overridable Sub M(ByVal x As Integer)
Console.WriteLine("B's M({0})", x)
End Sub
End Class
' The derived class D hides the inherited method M.
'
Public Class D
Inherits B
Shadows Public Sub M(ByVal i As Integer)
Console.WriteLine("D's M({0})", i)
End Sub
End Class
Public Class Test
Public Shared Sub Main()
Dim dinst As New D()
' In Visual Basic, the method in the derived class hides by
' name, rather than by signature. Thus, although a list of all the
' overloads of M shows three overloads, only one can be called from
' class D.
'
Console.WriteLine("------ List the overloads of M in the derived class D ------")
Dim t As Type = dinst.GetType()
For Each minfo As MethodInfo In t.GetMethods()
If minfo.Name = "M" Then Console.WriteLine( _
"Overload of M: {0} IsHideBySig = {1}, DeclaringType = {2}", _
minfo, minfo.IsHideBySig, minfo.DeclaringType)
Next
' The method M in the derived class hides the method in B.
'
Console.WriteLine("------ Call the overloads of M available in D ------")
' The following line causes a compile error, because both overloads
' in the base class are hidden. Contrast this with C#, where only
' one of the overloads of B would be hidden.
'dinst.M()
dinst.M(42)
' If D is cast to the base type B, both overloads of the
' shadowed method can be called.
'
Console.WriteLine("------ Call the shadowed overloads of M ------")
Dim binst As B = dinst
binst.M()
binst.M(42)
End Sub
End Class
' This code example produces the following output:
' ------ List the overloads of M in the derived class D ------
' Overload of M: Void M(Int32) IsHideBySig = False, DeclaringType = B
' Overload of M: Void M() IsHideBySig = False, DeclaringType = B
' Overload of M: Void M(Int32) IsHideBySig = False, DeclaringType = D
' ------ Call the overloads of M available in D ------
' D's M(42)
' ------ Call the shadowed overloads of M ------
' B's M()
' B's M(42)
Remarques
Lorsqu’un membre d’une classe dérivée est déclaré avec le modificateur C# new ou le modificateur Visual Basic Shadows , il peut masquer un membre du même nom dans la classe de base. C# masque les membres de la classe de base par signature. Autrement dit, si le membre de la classe de base a plusieurs surcharges, la seule qui est masquée est celle qui a la signature identique. En revanche, Visual Basic masque toutes les surcharges de classe de base. Par conséquent, IsHideBySig retourne false sur un membre déclaré avec le modificateur Visual Basic Shadows et true sur un membre déclaré avec le modificateur C# new .
Avertissement
Cette propriété ne détermine pas si une méthode a l’attribut NewSlot . Une méthode déclarée avec le ou le Shadows modificateur aura l’attribut, mais seules les NewSlot méthodes déclarées avec new (c’est-à-dire, seules les méthodes C#) auront la IsHideBySig propriété définie sur true.new Pour déterminer si une méthode a l’attribut, utilisez un NewSlot code similaire à ce qui suit : if ((myMethodInfo.Attributes & MethodAttributes.VtableLayoutMask) == MethodAttributes.NewSlot) en C# ou If (myMethodInfo.Attributes And MethodAttributes.VtableLayoutMask) = MethodAttributes.NewSlot en Visual Basic. Notez toutefois que bien que toutes les méthodes déclarées avec new ou Shadows aient l’attribut NewSlot , toutes les méthodes qui ont l’attribut NewSlot sont déclarées avec new ou Shadows.
