Where To Find Base Type Of A Class
Jun 9, 2009
One thing that always bugged me, is that I do not see the base type in Visual Studio.I just stumbled on this, because I tried to cast a System. Windows.Forms.MenuItem to a System.Windows.Forms.Control..In eclipse the "intellisense" (or whatever it is called) shows me while exploring the members of a class for each member from which base class it is inherited.In Visual Studio I cannot see the base class, even if I use the Object browser or the help.[code]Is there a way to query the base type tree of a class at Design Time?
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Nov 23, 2009
I have a copy function that I'd like to override in subclasses to return the type of the subclass. Here are my interfaces:
Public Interface IBase(Of T)
Function Copy() As T
End Interface
[Code]....
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Sep 25, 2009
I suspect I am being very silly here but I have the following setup
Class MustInherit myBaseClass
'some stuff
End Class
Class myInheritedClassA
[code]....
Running this results in the following error
Unhandled Exception: System.InvalidOperationException:
There was an error generating the XML document. --->
System.InvalidOperationException:
[code]....
is there any way of 'Widening' the inherited class to the base class so this would work?
EDIT:regarding XmlInclude(typeof inheritedClass), currently this method could potentially return a number of types of inherited class (i.e myInheritedClassA and myInheritedClassB) is it case of simply having to add each of the inheritedTypes in this tag?
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Mar 30, 2010
1) VB Allows non-type template parameters2) VB supports explicit specialization 3) VB allows the type parameters to be used as the base class for the generic type4) VB allows a generic type parameter itself to to be a generic 5) VB enforces that all codes are valid for all types of parametrs
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Apr 13, 2012
Consider:
Public MustInherit Class Column
Public ReadOnly Property ReturnSomethingUseful() As Object
Get
'return something useful
[code]....
But this gives the following error:
Public Overrides Function ParseValue(sValue As String) As Boolean'
cannot override 'Public Overridable Function ParseValue(sValue As String) As Object'
because they differ by their return types.
I accept that you can't do this, but I'd like to be able to preserve the semantics of what I'm. trying to do, which is to have an untyped version that deals with Object, but a typed version in derived classes that knows about the specific type T.
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Nov 16, 2009
take a look at the following code:
[Code]...
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Mar 12, 2010
When I do this
Public Class cInherits : Inherits Panel
I get this: Base class 'System.Windows.Forms.Panel' specified for class 'MenuButton' cannot be different from the base class 'System.Windows.Forms.UserControl' of one of its other partial types.
How do I inherit?
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Apr 15, 2010
I have put this code in the global form Inherits System.Windows.Forms.Form. And then in the form that will inherit this from the global Inherits MenuStrip. "MenuStrip" is what the global form is called. But keep getting this error: Error1Base class 'MenuStrip' specified for class 'Lesson2' cannot be different from the base class 'System.Windows.Forms.Form' of one of its other partial types.
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Aug 20, 2009
I have a number of controls (Device1, Device2, etc.) that all inherit from BaseDeviceControl. In the DragEnter event handler I am trying to test for the correct type by using the BaseDevvceControl like this....
[Code]....
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Oct 1, 2008
I've been creating short test apps repeatedly to try to understand some of the concepts in VB.NET.For the most part it has been illuminating.I read Bucky's .NET knowlegebase tutorial on passing objects as parameters to newly created forms. He shows how to create a new class that inherits from the base form class and define a New() method with parameters Extending the concept I thought about doing the same thing with a form that was created at design-time (In this case Form2).
[Code]...
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Apr 22, 2012
Base class has one field to hold numeric balance value. With 2 methods that accept arguments for adding and subtracting the new input calculating new balance. Sub class has four fields dates, transaction, memo and amount.I have a deposit form, and withdraw form. Each time one transaction is entered it creates an object with sub class fields, then adds to the account collection. My problem is not understanding how to call the deposit/withdraw method and pass the current transaction amount back to the base class to alculate the new balance. Does anyone have any links to information/tutorials on how to perform something like this? As you can see with my code I have tried various different approaches without any success.
[Code]...
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Apr 7, 2011
Supose a base class
Public Class airplane
Private var_num_seats As Integer
Private var_num_engines As Integer
[code]....
Obviously, I don't wish that the class Glider has the method "start_engines" neither the property "num_engines". Otherwise, other child classes may have. How can I supress these property and method in child class, not just ignoring (if I can)?
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Apr 9, 2010
I am trying to create a class in VB.NET which inherits a base abstract class and also implements an interface. The interface declares a string property called Description. The base class contains a string property called Description. The main class inherits the base class and implements the interface. The existence of the Description property in the base class fulfills the interface requirements. This works fine in C# but causes issues in VB.NET.
[Code]...
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Dec 29, 2010
This is another one of my "I think it's not possible but I need confirmation" questions.I have a base class for a bunch of child classes. Right now, this base class has a few common properties the children use, like Name. The base is an abstract class (MustInherit)Technically, this means that everytime a child class is instantiated, it lugs around, in memory, its own copy of Name. The thing is, Name is going to be a fixed value for all instances of a given child. I.e., Child1.Name will return "child_object1", and Child2.Name will return "child_object2".
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Jun 10, 2011
Suppose I have piece of code like this:
Public Interface ISomething
....
End Interface
[code]....
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Jun 29, 2010
I'm wrestling with this treeview control. I have extended the TreeNode class to attach some extra data to the node. Basically, I added one property:[code]Is there a way to cast from a base type to a derived type?
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Oct 22, 2010
How do I access the base class inside a derived class?
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Dec 10, 2010
If we are within the derived class then ofcource we can use MyBase keyword to access base class's object reference . That's fine , how can we take that base class's object reference outside that derived class's definition.My following code will explain what i want . Actually that is giving error right now, but it is explaining my requirement .
Public Class Base
Public x As String
End Class
[code]....
Actually there is error in ReadOnly Property BaseReference's Getter . Error is "Error 1 'MyBase' must be followed by '.' and an identifier. " how can i get base class object reference in Main method ?
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Jul 19, 2010
[code]The reason that this is a problem is that this is a collection of EventBase objects, but I'm trying to populate it with child classes instead. For example, I might have a JumpEvent class that inherits EventBase, and this is being put into the EventBaseCollection. That means that value.GetType() returns the type of JumpEvent, which as you might guess does not equal the type of EventBase.The goal of course is to simply loop through all of the various events without having to know anything about the sub-classes. Is there a way to determine the type of the base class so that the OnValidate call will work? Or is this just the wrong way to go about it altogether?
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Jun 2, 2009
I understand that inherited classes can't be converted from base classes. But is there any way to write a conversion sub, so that the base class gets assigned to MyBase, then extra properties are added?[code]...
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Jul 5, 2010
bare with me during this silly example. :-) Let's say I have a class like this:
Public Class Animal
Public iLegs as int32 ' Number of legs
Public bWings as Boolean ' Wings? Yes/No
End Class
And another class that inherits the "Animal" class and adds one more property:
Public Class ScaryAnimal
Inherits Animal
Public iScariness as int32 ' 0-100, how scary is it?
End Class
Now, if I have an instance of "Animal" with some values in it, and I decide I want to cast it to a ScaryAnimal for some reason, how do I do that without having to create a new instance of "ScaryAnimal" and copy each property value?Basically I'm looking for a way to do this, without having to write the lines marked with '*** below:
[Code]...
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Feb 4, 2009
I have a base class called PageBase and then a derived class TestPage that inherits from PageBase. In PageBase I have overridden the OnInit() and when it is called and I inspect the value of 'Me', it is of the type of the derived class and not the base class. My question is how does inheritance really work? For instance, when instantiating TestPage does an instance of PageBase get created too?
Here is my code;
Partial Public Class TestPage
Inherits PageBase
Public Sub New()
[code]...
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Oct 19, 2009
What is the base class of .NET?
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Dec 29, 2011
Is anyone any good with Databases & VB if so could you give me your opinion on the diagram i have drew and my application.ive never used a database before but would like to encorprate one into my app - i have done a diagram - i would like to know if it is possible to do and what type of data base would be esiest to do it with.
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Mar 16, 2011
When referencing a method's address, should we take into account the overriding or not?
Class B
Inherits A
Overrides Sub Foo
[code].....
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Mar 5, 2010
When you create a webpage in ASP.net, the codebase inherits System.Web.UI.Page Now when I extend the page object to check for SessionExpired for example, I create a new class and inherit from system.web.ui.page, and overwrite some functions. The problem then is that on each page, I have to replace system.web.ui.page with my custompage class. Is there a way to extend a class by adding methods or modifying its methods directly (e.g. add the sessionExpired check to System.Web.UI.Page) ?I'm using .NET 2.0
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Sep 7, 2011
Any best practices on how to deal with different versions of base classes.We have made significant changes to the base class but still have lots of code inheriting from the old base class. Could you recommend how we introduce new base class.We'd like all new code to use the new base class. But, we would like the option to have old code still inherit from old base class so we have time to switch and test old classes with new base class.
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Jul 17, 2010
I have a class library that have a lot of classes, in every class I have "Inherits LINQDataContext". And In my xx.designer.vb file I have...
Public Sub New()
MyBase.New(Global.My.MySettings.Default.DbConnectionString, mappingSource)
OnCreated()
End Sub
But I get a lot of "Class 'xxxxx' must declare a 'Sub New' because its base class 'LINQDataContext' has more than one accessible 'Sub New' that can be called with no arguments." errors
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Jun 4, 2010
I am trying to add shared members in derived classes and use that values in base classes...
I have base
class DBLayer
public shared function GetDetail(byval UIN as integer)
dim StrSql = string.format("select * from {0} where uin = {1}", tablename, uin)
end function
end class
[Code]..
currently there is error using the tablename variable of derived class in base class but i want to use it i dun know other techniques if other solutions are better then u can post it or u can say how can i make it work? confused...
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Mar 9, 2010
Is there a way to get an enum to explicitly cast to it's base type?If I have something like this:
Code:
Public Enum Packets As Byte
Stuff = &H0
End Enum
I have to do
Code:
Dim test As Byte = CByte(Packets.Stuff)
Rather than
Code:
Dim test As Byte = Packets.Stuff
I don't see why that's the way it works, since you know that the enum will always have values of the base type.
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