.net - Interface Inheritance: Method Does Not Show Up
Feb 15, 2010
I've got an interface inheritance issue that has been vexing me for some time. It doesn't seem to make any sense, and I can only conclude that I'm missing something fundamental.
Overview The code below is from part of a fluent interface for our ORM tool. It provides a SQL-like syntax for pulling data from the database. You don't have to completely grok all the interrelations to understand the problem -- the real issue is the EndClause method.
The EndClause Issue There's a method called EndClause that doesn't show up in one expected spot -- IOrderQueryRoot. As far as I know, it should show up because it inherits from two different interfaces that both have a method called EndClause, but when I consume an object that implements IOrderQueryRoot, EndClause does not pop up in intellisense.
There are some more implementation details below.First though, if you look at IOrderQueryRoot (which contains EndClause), you can see that it inherits IHasOrderLogicalOperators, and also IHasOrderFields (which also contains EndClause).
Public Interface IHasOrderLogicalOperators
Function [And]() As IHasOrderFields
Function [AndNot]() As IHasOrderFields
[code]....
At this point, the interface is working fine -- if I were to remove this method, VS would scream that I have to implement both EndClause methods. The problem is one level down, when the "end developer" is trying to actually write code against the interface.
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Nov 25, 2011
I have a large problem with inheritance in vb.net. The problem is the following:
I have 2 forms => frmBase and frmChild
In frmBase i want to create a method Called StartWorking() and i want frmChild to inherit this method.
But here is the tricky thing: when frmChild.StartWorking is called i would like the following => without calling MyBase.StartWorking()
I want frmBase.StartWorking() to be executed first and after a test in frmBase.StartWorking if blnValue is true then frmChild.StartWorking has to be activated. if blnValue is false that frmChild.StartWorking cannot be activated.
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Apr 15, 2011
I'm facing a problem regarding multiple inheritance in VB.net:As far as I know VB.net does not support multiple inheritance in general but you can reach a kind of multiple inheritance by working with interfaces (using "Implements" instead of "Inherits"):
Public Class ClassName
Implements BaseInterface1, BaseInterface2
End Class
That works fine for classes but I'd like to have an interface inheriting some base interfaces. Something like that:
[Code]...
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Jan 6, 2012
How can I convert following code to VB.NET?
class A
{
public int NumberA { get; set; }
}
[code]....
In VB.NET there is problem with Implements keyword after property declaration. So I need to do something like this:
Class B
Inherits A
Implements IC
[code]....
But there is duplicit misleading property NumberA1.
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Dec 18, 2009
I m trying to understand Interfaces so that I can implement them in my programs but I m not able to imagine how should i use them.Also give me some eg of using them with multiple inheritance in C#
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Jun 18, 2010
This question is a follow-up to my last question with a reference to COM Interop. Let's say I have the following 2 interfaces and implementing classes:
[Code]...
Interfaces are important in COM interop for exposing properties and methods to IntelliSense in the VB6 IDE (per this article). However, because ICartItem is inherited from ISkuItem, SKU is not explicitly defined in ICartItem and thus is not visible in IntelliSense in VB6 and even throws a compiler error when trying to write to objCartItem.SKU.
I've tried using Shadows and Overloads on the SKU property in ISkuItem, but then the compiler wants me to explicitly implement SKU for both ISkuItem and ICartItem within the CartItem class. I don't think that's what I want. Is there a way (in either VB.NET or C#) to explicitly declare the SKU property in ICartItem without having to declare SKU twice in the CartItem class?
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May 26, 2011
Is this possible in object-oriented design? I'd like to specify that in an inheritance tree, the type of a property in the child classes is different from the type of that property in the parent class. But the types are polymorphic because they derive from the type used in the parent class. e.g.:
[code]....
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Jan 9, 2010
I have a C# interface defined as so:
public interface IMenuSecurityService
{
void SetSecurityFlags(List<MenuItem> items);
}
I need to implement this interface in a VB.Net class. When I implement the SetSecurityFlags method with the items parameter passed ByVal, it compiles.
Public Sub SetSecurityFlags(ByVal items As List(Of L1.Common.Model.MenuItem)) Implements IMenuSecurityService.SetSecurityFlags
' do some work
End Sub
When I try to implement it with the items parameter passed ByRef, I get the following compiler error: Class 'UserRights' must implement 'Sub SetSecurityFlags(items As System.Collections.Generic.List(Of Model.MenuItem))' for interface
Public Sub SetSecurityFlags(ByRef items As List(Of L1.Common.Model.MenuItem)) Implements IMenuSecurityService.SetSecurityFlags
' do some work
End Sub
I can't seem to figure this one out. Does VB.Net not support this or am I doing something wrong?
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Jan 11, 2011
In Visual Studio, when you right-click a method call, you go to the implementation of that method inside a class except if you access this method through an interface: in that case you go to the interface method not to the actual implementation.Is there a way / tips (key shortcut or anything) to access this actual implementation ? Otherwise you are stuck to add some comment just to remember where you did implement it that's really not productive and error prone !
Update: interesting answers but I'm not really satisfied because all are cumbersome. I will give a precise example:
IInterface iInterface = someObject;
iInterface.someMethod();
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Jun 28, 2011
Does anybody know why I get the error 'that method is not available on that object' when I try to interface with Word 10? Our software works fine with Word 7 and previous
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Mar 3, 2009
Attempting to invoke a method of an interface, of which the return type is _variant_t
Code:
_variant_t resultsDataString;
_bstr_t simObjectNames;
simObjectNames = SysAllocString (L"TEST example 3");
resultsDataString = pis8->GetSimObject (simObjectNames);
[code].....
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Jan 6, 2011
I have an interface ITest with a method GetResult(). I have a class Test which implements ITest and thereby defines private method GetResult().
Next I create an instance of Test in a different class. The code is as below:
Module NewClass
Public Sub New()
Dim i As ITest = New Test()
[Code]....
I am migrating existing code from VB 6 to VB.NET and hence I'm not supposed to change the access modifier of GetResult. Leaving it Private will throw InvalidCastException Unable to cast object of type 'System.Object' to type 'ITest'
Object type variable o is used in many places and hence I don't want to change that. And yes, Test implements ITest.GetMember with a different name.
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Aug 18, 2009
I have an application in VB2008(GUI) and MySql as database. I want show my interface in Internet Explorer. How does this interface work on web access.
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Nov 20, 2010
Is it possible to show more than one user interface at a single time in order to show how to show how all relate in real time?
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Nov 15, 2009
How to control the location where the OpenFileDialog.Show places the interface on the screen?
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Jul 18, 2012
I am programming an ordering site in VB.Net and ASP.Net.I start with the main ordering form and the idea is that the user will select a subject from the drop down list and then click a button to retrieve all modules associated with that subject in a second form (smaller than the main order form).I have created the second form (frm2) and added content to it.In the main form inside the method which represents the button being clicked, I have coded the following:
Dim frm As New frm2()
frm.show()
I then get an error that show has not been declared and so I create a method stub for it.I run the program and when I click on the button I get the following error:'method or operation is not implemented.'This points to the following line in the 2nd form:
Sub show()
Throw New NotImplementedException
End Sub
what I need to put inside this method to make my second form load when the button is clicked?
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Aug 21, 2009
Why i can't use method dot show in my visual studio 2008 and Why i must declaration object for using method dot show, example[code]...
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Jul 15, 2010
I am trying to get a label to show briefly (3 seconds) when the form loads. The following code gives the 3 seconds, but the label doesn't show. The label is set to visible in the Designer properties.[code]
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Oct 23, 2008
Is there a way to have a form within a program that doesn't dispose when you close it? I have a form in my project and a menu item to show it. When I declare the form globally and show in menuItem.click, then the click event breaks because the form no longer exists. When I declare the form within menuItem.click, then this creates a new form every time I click and that's not what I want.
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Feb 7, 2010
I have a simple login field, which works fine with the exception of one quirk. The form is set up with the tab order to go to the UserID first and the Password text box second. This works fine when the form is used the first time, but when the form is used the second time the focus in placed in the Password field. If the form is used a third time, focus is moved the OK button, that is each time moves to the next tab order. I even tried to set the focus in the Load event as in Me.txtUserID.Focus(), but this doesn't change the behavior. Again, I should note that I close the form and not hide the form.
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Oct 19, 2010
Consider a MyForm class that contains a shadowed implementation of Show(). It also contains a CreateForm() method, which accepts an instance of the form and calls the shadowed sub:
[Code]....
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Jan 12, 2010
how to create a user interface in a game such as the application XFire using Visual Basic?
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Oct 19, 2008
I'm working on a design project where I have to use a Graphical User Interface that contains a drag and drop form. It consists of having a window dropped on a wall. Both of them are images to scale. I would like to know what kind of code I would have to use to show the x and y coordinates of one of the points of my window when dragged so when I drop it, I'm dropping in it on the desired coordinate of the wall.
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May 18, 2012
I was wondering if I could elicit some tips on how to procede with an interface design approach.That is. What is a good way to go about establishing a "work area" where one can have multiple "floating forms" in this area.Can you have a form which occupies the entire windows desk top and the other forms "float" in this space? the "floating" forms would need to interact with each other where pressing buttons etc on them would affect other forms on the "workspace") Or what would be a good way to start accomplishing that? Or is there a better way to get the same effect?
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Apr 21, 2010
I'm trying to make a .dll that contains a lot of basic functionality that a program can use. Currently i am trying to use interfaces to make a lot of this functionallity independend of the program using it but i hit a snag. The Basic idea is that a programmer will create his own object using the interface discribed in my .DLL file. Then implements those functions as he likes. He can then instanciate a controller (found in the same DLL) and sends his custom object implementing the interface to that Controller. The controller can then be started and will take over all the work. I do not know what type of object is send to the controller and idealy i want to program it in such a fashion that i shouldn't care as long as the object send implements that interface.In code I am trying to achieve the following: (quite simplyfied)
.Dll:
Code:
Public Interface MyInterface '<----Decleration of the interfaceFunction GetData() As Integer
Function SetData(Data As Integer)
end interface
[code]....
this propperly. I know that the second i set the interface adaptor in the Controller VS comes nagging that it can not be converted to a "MyInterface" Class. Obviously i am doing something wrong. I can change the datatype that the controller expects to the "MyController" type but that would completely ruin the whole idea of flexibillity. I am hoping someone sees what i am trying to do and can point out where i made the thinking error.
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May 21, 2012
Is this where i would post a picture of my interface and get feedback on changes for easier use? If not is there someplace on this forum or any other forum to do this?
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Apr 22, 2012
i am just trying to apply inheritance ..Below is my Code ... on which i am not getting the output on my Text_Box ... when in write it in a Child Class
Imports System
Imports System.Windows
Imports System.Windows.Forms
[code]....
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Jul 14, 2011
Has someone a hint what I'm doing wrong in VB.Net?
Module Module1
Interface ISearch(Of T As ISearchResult)
Function ids() As List(Of T)
End Interface
[CODE]...
The third cast isn't working. Why? did I miss a oop lesson?
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Mar 2, 2011
What's the choice design that microsoft do that? Of course, as of me, I don't use inheritance a lot, or at all.
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Nov 18, 2011
in the codebase i'm maintaining there is an old interface. Let's call it IFoo. It pretty much became obsolete and replaced with the Interface INewFoo with a change a few weeks ago, but for backwards-compatibility purposes, i wrote a wrapper class which implements INewFoo and takes an IFoo in the constructor.To clarify, consider the following code.
Public Interface IFoo
Sub DoStuff()
End Interface[code].....
For both interfaces, the implementations are loaded by scanning a few assemblies with StructureMap. Now, let's get to the bad things. Most implementations for the old interface were put into forms for reason i can neither understand nor change. Because those tend to be displayed and disposed, i have to create a new instance every time i use ObjectFactory.GetAllInstances(Of IFoo). Thats still no problem, but i'd like to register a INewFoo-Wrapper for each registered implementation of IFoo, so that i can just use ObjectFactory.GetAllInstances(of INewFoo) and get all implementations of IFoo AND INewFoo.I can't iterate through the implementations of IFoo and register a wrapper for each one because as far as i can see, you can just register those with instances.Wrong code below:
ObjectFactory.Configure(Sub(config)
config.Scan(Sub(scan)
For Each ass In assemblies[code].....
My question is: Is it possible to register a wrapper for each implementation of IFoo which always creates a new instance of the implementation before creating a new instance of the wrapper?
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