MethodBase.IsHideBySig Property
Definition
Important
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Gets a value indicating whether only a member of the same kind with exactly the same signature is hidden in the derived class.
public:
property bool IsHideBySig { bool get(); };public bool IsHideBySig { get; }member this.IsHideBySig : boolPublic ReadOnly Property IsHideBySig As BooleanProperty Value
true if the member is hidden by signature; otherwise, false.
Implements
Examples
The following code example contains a base class with an overloaded method, and a derived class that hides one of the overloads. In the Visual Basic version of the code example, the IsHideBySig property returns false for the member in the derived class. In the C# version of the code sample, the property returns true for the member in the derived class.
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)
Remarks
When a member in a derived class is declared with the C# new modifier or the Visual Basic Shadows modifier, it can hide a member of the same name in the base class. C# hides base class members by signature. That is, if the base class member has multiple overloads, the only one that is hidden is the one that has the identical signature. By contrast, Visual Basic hides all the base class overloads. Thus, IsHideBySig returns false on a member declared with the Visual Basic Shadows modifier, and true on a member declared with the C# new modifier.
Warning
This property does not determine whether a method has the NewSlot attribute. A method that is declared with either the new or the Shadows modifier will have the NewSlot attribute, but only methods declared with new (that is, only C# methods) will have the IsHideBySig property set to true. To determine whether a method has the NewSlot attribute, use code similar to the following: if ((myMethodInfo.Attributes & MethodAttributes.VtableLayoutMask) == MethodAttributes.NewSlot) in C# or If (myMethodInfo.Attributes And MethodAttributes.VtableLayoutMask) = MethodAttributes.NewSlot in Visual Basic. Note, however, that although all methods declared with new or Shadows have the NewSlot attribute, not all methods that have the NewSlot attribute are declared with new or Shadows.
