Hide members in a derived class

[Paul Wu]

Is there a way to constract a derived class that hides certain public members of a base class ?
With the following code, a class that derives from DerivedClass can still see the member "Name" in the base class. Can anyone provide me with an example that will do what I need?

Public Class BaseClass
Private mName As String = "Bob"
Public Overridable Function Name() As String
Name = mName
End Function
End Class

Public Class DerivedClass : Inherits BaseClass
Private Shadows Function Name() As String
Name = "Joe"
End Function
End Class
--------------------------------
Thanks,
Paul Wu

[Cor Ligthert]

Paul,

No you can't. You will see this behaviour as well in some of the standard controls who derive from control. Some members do just nothing.

I hope this helps anyhow,

Cor

[Bob Powell [MVP]]

Classes will always have the methods and properties they were created with. You cannot hide these from code but you can hide them from the eyes of your users if you know what you're doing.

In the case of a class that is examined at design-time by the property grid you can hide classes by creating a designer for your class and overriding the PreFilterProper ties or PostFilterPrope rties methods. These take the list of properties obtained by reflection and remove enable you to add or rmove property descriptors. This is how the Browsable attribute works to enable certain properties to be visible at design time.

The trick of overriding the class and marking a property as browseable or not is also a possibility for design-time usage but is IMO not quite so desirable.

If you're code presents properties in some other way at runtime, perhaps through the property grid or some other form of reflection, you can make your class implement ICustomTypeDesc riptor. This interface enables you to preemptively filter properties and can be used at runtime without a designer.

--
Bob Powell [MVP]
Visual C#, System.Drawing

Find great Windows Forms articles in Windows Forms Tips and Tricks
http://www.bobpowell.net/tipstricks.htm

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"Paul Wu" <pw*@spam.encor ecredit.com> wrote in message news:un******** *****@TK2MSFTNG P15.phx.gbl...
Is there a way to constract a derived class that hides certain public members of a base class ?
With the following code, a class that derives from DerivedClass can still see the member "Name" in the base class. Can anyone provide me with an example that will do what I need?

Public Class BaseClass
Private mName As String = "Bob"
Public Overridable Function Name() As String
Name = mName
End Function
End Class

Public Class DerivedClass : Inherits BaseClass
Private Shadows Function Name() As String
Name = "Joe"
End Function
End Class
--------------------------------
Thanks,
Paul Wu

[Cor Ligthert]

Bob,

In the case of a class that is examined at design-time by the property grid
you can hide >classes by creating a designer etc.

I wrote this in a way like you as well and deleted that again, because it is
for somebody who create classes in my opinion not interesting.

The chalenge is in my opinon to let the members never (directly) been showed
in a derived class . (With directly I mean without casting).

When you have a solution for that, than I will be glad when you can show
that and do I probably miss something.

Cor

[Bob Powell [MVP]]

The only sensible way to do what you're suggesting is to use the memento
pattern...

Otherwise, the suggestions I made are the only possible alternatives.

--
Bob Powell [MVP]
Visual C#, System.Drawing

Find great Windows Forms articles in Windows Forms Tips and Tricks
http://www.bobpowell.net/tipstricks.htm

Answer those GDI+ questions with the GDI+ FAQ
http://www.bobpowell.net/faqmain.htm

All new articles provide code in C# and VB.NET.
Subscribe to the RSS feeds provided and never miss a new article.

"Cor Ligthert" <no************ @planet.nl> wrote in message
news:%2******** ********@tk2msf tngp13.phx.gbl. ..

Bob,

In the case of a class that is examined at design-time by the property
grid you can hide >classes by creating a designer etc.

I wrote this in a way like you as well and deleted that again, because it
is for somebody who create classes in my opinion not interesting.

The chalenge is in my opinon to let the members never (directly) been
showed in a derived class . (With directly I mean without casting).

When you have a solution for that, than I will be glad when you can show
that and do I probably miss something.

Cor