If the answer is "to make strongly typed collections", then I can do
this with an ArrayList by taking advantage of the Shadows keyword, as
follows:
Public Class clsMyClass
Inherits System.Collecti ons.ArrayList
Public Shadows Sub Add(ByVal o As clsMyItem)
MyBase.Add(o) '.Add only allows objects of type clsMyItem to be
added to this ArrayList class.
End Sub
Public Shadows Property Item(ByVal i As Integer) As clsMyItem
Get
Return CType(MyBase.It em(i), clsMyItem)
End Get
Set(ByVal Value As clsMyItem)
MyBase.Item(i) = Value
End Set
End Property
End Class
There must be other reasons for using a CollectionBase, but what are
they please?
Regards, dnw. 4 2180
I think that if somebody casts your clsMyClass to an ArrayList, he will be
able to add objects of other types to it (not clsMyItem). The CollectionBase
allows you to override OnInsert, OnValidate, etc. and to prevent that.
--
Best regards,
Carlos J. Quintero
MZ-Tools: Productivity add-ins for Visual Studio .NET, VB6, VB5 and VBA
You can code, design and document much faster.
Free resources for add-in developers: http://www.mztools.com
<do***@hotmail. com> escribió en el mensaje
news:11******** *************@f 14g2000cwb.goog legroups.com... If the answer is "to make strongly typed collections", then I can do this with an ArrayList by taking advantage of the Shadows keyword, as follows:
Public Class clsMyClass Inherits System.Collecti ons.ArrayList
Public Shadows Sub Add(ByVal o As clsMyItem) MyBase.Add(o) '.Add only allows objects of type clsMyItem to be added to this ArrayList class. End Sub
Public Shadows Property Item(ByVal i As Integer) As clsMyItem Get Return CType(MyBase.It em(i), clsMyItem) End Get Set(ByVal Value As clsMyItem) MyBase.Item(i) = Value End Set End Property End Class
There must be other reasons for using a CollectionBase, but what are they please?
Regards, dnw.
You've had to do the same amount of work to coerce the ArrayList in a pretty
lousy OOP example when the CollectionBase is a great blank-slate upon which
to draw.
--
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.
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<do***@hotmail. com> wrote in message
news:11******** *************@f 14g2000cwb.goog legroups.com... If the answer is "to make strongly typed collections", then I can do this with an ArrayList by taking advantage of the Shadows keyword, as follows:
Public Class clsMyClass Inherits System.Collecti ons.ArrayList
Public Shadows Sub Add(ByVal o As clsMyItem) MyBase.Add(o) '.Add only allows objects of type clsMyItem to be added to this ArrayList class. End Sub
Public Shadows Property Item(ByVal i As Integer) As clsMyItem Get Return CType(MyBase.It em(i), clsMyItem) End Get Set(ByVal Value As clsMyItem) MyBase.Item(i) = Value End Set End Property End Class
There must be other reasons for using a CollectionBase, but what are they please?
Regards, dnw.
dnw,
Here is the best article I have seen on type-safe collections in .Net: http://www.ondotnet.com/pub/a/dotnet...ns.html?page=1
Kerry Moorman
"do***@hotmail. com" wrote: If the answer is "to make strongly typed collections", then I can do this with an ArrayList by taking advantage of the Shadows keyword, as follows:
Public Class clsMyClass Inherits System.Collecti ons.ArrayList
Public Shadows Sub Add(ByVal o As clsMyItem) MyBase.Add(o) '.Add only allows objects of type clsMyItem to be added to this ArrayList class. End Sub
Public Shadows Property Item(ByVal i As Integer) As clsMyItem Get Return CType(MyBase.It em(i), clsMyItem) End Get Set(ByVal Value As clsMyItem) MyBase.Item(i) = Value End Set End Property End Class
There must be other reasons for using a CollectionBase, but what are they please?
Regards, dnw.
Thanks for all replies, especially Kerry's excellent link.
Kerry Moorman wrote: dnw,
Here is the best article I have seen on type-safe collections in .Net:
http://www.ondotnet.com/pub/a/dotnet...ns.html?page=1
Kerry Moorman
"do***@hotmail. com" wrote:
If the answer is "to make strongly typed collections", then I can do this with an ArrayList by taking advantage of the Shadows keyword, as follows:
Public Class clsMyClass Inherits System.Collecti ons.ArrayList
Public Shadows Sub Add(ByVal o As clsMyItem) MyBase.Add(o) '.Add only allows objects of type clsMyItem to be added to this ArrayList class. End Sub
Public Shadows Property Item(ByVal i As Integer) As clsMyItem Get Return CType(MyBase.It em(i), clsMyItem) End Get Set(ByVal Value As clsMyItem) MyBase.Item(i) = Value End Set End Property End Class
There must be other reasons for using a CollectionBase, but what are they please?
Regards, dnw.
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