is there any reason why we couldn't add/extend an interface to an already existing class?
i believe this would be v useful. it would be like drawing links from my class to already existing classes, and drawing links from already existing classes to already existing classes
How can I structure my classes so that the user interfaces though a single class while the supporting classes are hidden from their view? I think its best understood in an example:
Public Class MyInterface
Public Economic as EconomicClass
Public Sub New()
MyBase.New()
[code].....
So you might ask why am I even separating them? It's strictly for others who will be working with this interface. I need to funnel them though a logical structure:
interface.Economic.MyMethod
interface.Currency.MyMethod
etc
This way everything is already handled for them in the background and they only need to run the method they need. I don't know if I can have it both ways in VB.NET.
Sometime ago I used to create all my class structures in vision before I wrote them. That however didn't last. I found it easier to just make little drawings with pencil and piece of paper. And I still do to this day. In code usually those drawings manifest themselves as interfaces which then are implemented by different classes. I do all this in code. And I was just wondering if there is any tools available in Visual Studio for VB.NET that would allow to create interfaces and implement them in classes (which a lot of times means just adding variables to class that will hold data passed with interface attributes) from design mode(kinda like using Visio only after you finish you don't have to write out code).
View 3 RepliesI am trying to create an interface and then about 3 or 4 singleton classes that would be accessed via the interface.I know how to get interfaces to work and I know how to create concrete singleton classes and access them via GetInstance(). But when I put the two together, failure results.My problem is in the GetInstance method of the concrete singletons as in
Public Class MovingList
implements ISelectedList
[code]....
ISelectedList is the interface. This fails because ISelectedList.GetInstance is not of the type MovingList. Plus there is a problem with the use of Shared that I think is solved by simply deleting it (interfaces implicitly share).I can't define the type of ISelectedList.GetInstance because each of my singleton classes is of a different type even though they implement exactly the same properties and methods.How best to implement such singleton classes? I could do away with the interface and simply deal directly with the concrete singletons but that feels like bad practice. Programming to an abstraction not an implementation and all that.
So say I define some interface, and that interface has members that need to be implemented under some idea, and I then implement this interface on a class that already has those members defined. How do I NOT receive errors about having to implement said members despite them already being implemented (because I didn't type the oh so ridiculous 'implements IMyInterface.foo').
For example say I have an interface that defines the event KeyPress, and then I have a custom Form that implements this interface of mine. It throws an error. VB is the 5th language I've worked in that uses interfaces... and up until now they've all treated interfaces relatively the same. This is the first time I've seen this not allowed. What perplexes me more, is it IS allowed in other .Net languages. Just not VB.
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So in a lot of frameworks there is usually some base type that you tend to extend a lot because well, it is what enables the "visual" aspect of the framework. Here in .Net it's the Control/Form... you tend to be inheriting these frequently for different things, and despite the suggestions otherwise, the team always agrees to extend explicitly and forget about composition.So now say you want to create some relationship between all of these... just a simple interface that uncovers some basic properties that all your forms and controls should have. In this case lets call it 'IProjControl'
Code:
Public Interface IProjControl
Property ProjControlId() As String
[code]....
So this interface is something you expect all your windows and dialog boxes and other some other controls implement. They all don't extend the same exact type, they all just happen to be controls.In there lies the problem... you want to enforce the contract with this interface that not only is it a 'IProjControl', but it's also a 'Control'. But we can't exactly have our interface extend Control (that doesn't make sense), and there isn't an 'IControl' interface to require implementing.
So the method I've always used is something like this:
Code:
Public Interface IProjControl
ReadOnly Property ProjControlComponent() As Control
Property ProjControlId() As String
[code]....
(if there is actually a language/compiler specific feature that allows you to require an interface implementation to be implemented by a class extending a specific type... please, do tell... but I highly doubt there is because for all intensive purposes that sounds weird).
When you develop a class library that will be used by others, are there any guidelines on how you decide what namespace to put it under? I often find third party classes just use the company name as the root namespace but I was also wondering if it is frowned upon (or even possible) to add one of your own classes to an existing framework namespace.
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As my latest questions have stated, i am in a process of researching on Silverlight 3 and its application as a suitable RIA solution to a pre-built project a client of ours wishes to webify. And my experience in .Net and silverlight is about 3 - 4 weeks.I have now become aware of .Net RIA Services. I require to use an existing VB class; which was created as a quick wrapper class to emulate a small piece of the client's application code. This is used as a proof of concept. It contains one function which uses the client's DLL files to return a simple data type This class has already been used successfully with Flex/Weborb combination.I unfortunately do not have enough knowledge or experience in Silverlight/RIA Services to grasp what it is i have to do to get the file working. All the examples I find online only specify the method where you use a database as dataSource etc.Could you please inform me how i would go about implementing RIA Services with Silverlight 3, using existing code/classes with no DB? Or could you point me in a direction for further research on the matter?
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EDIT: The above class is just an example of what could be returned from a web service. I won't have access to modify it at all, sorry if I didn't make that clear.Is it possible to somehow make a clone this class, so that it retains all of the properties values, but hides the fact that there is a Public function?I'd like to be able to take some existing classes we retrieve from a web service(which we didn't write) and be able to pass them on for use in an application, but without exposing the functions. I don't want to go down the route of creating my own classes that specifically define each property and write the values in (due to the sheer size of some of them), so I'm looking to see if there is anything dynamic I can utilise (maybe there is a way using reflection?).
I seem to be having a problem with controls that I am creating as new classes (not UserControls) inheriting from an existing system control. Everything seems ok while I create the control code, through to the compile (which is successful and adds the control to the toolbox) and dragging the control from the toolbox to the GUI surface. However, when I then debug or compile the project, I get a message such
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I have two classes, one nested in the other. [code]Neither "Name" or "ID" are unique between operations and records.I wish to construct a dictionary using LINQ = Dictionary(Of String, Of List(Of Integer), whereby the keys are uniqe examples of Names in my collection and the values are the collective set of distinct IDs that are associated with those names.
View 2 RepliesI need to make a program in vb that takes a 1 page existing pdf that i specify and inserts that into another existing pdf that i specify.
View 4 RepliesHere is some example code of what I mean:
vb
Public Class Form1
Private Sub Button1_Click(ByVal sender as Object, e as systemEventArgs) Handles Button1.Click
[Code]....
I m trying to raise Click event of Textbox explictly but I m getting "Derived classes cannot raise base classes" error.[code]....
View 1 RepliesAre Interfaces used often? Need opinions.
View 4 RepliesI have the following problem with MEF: Interface definition to be used by host:
Public Interface IExecuteDoSomething
Inherits IAddinSettings
Event DataReceived As EventHandler(Of DataReceivedEventArgs)
Function DoSomething() As Boolean
End Interface
[Code]...
Everything seems to work fine until the Button2_Click routine is executed, then an InvalidCastException is thrown with the info:Unable to cast object of type 'System.Collections.Generic.List1[SharedLibrary.IExecuteDoSomething]' to type 'System.Collections.Generic.List1[SharedLibrary.IAddinSettings]'.
How can i solve this problem, because the imported object implements both of the interfaces?
In this discussion let us discuss every usage of interfaces in .NET. Any real time examples and difficulties in using interfaces can also be discussed here.
View 6 RepliesIm building a game with VB.NET I designed the core of the game in form1 window But now I need menus. How can I implement this without having 5 or so windows that I show() and hide() ? Doing that slows it down a lot and uses lots of memory. I tried tabs, but I don't want the tabs to appear, just switch. Whats the best way to implement multiple interfaces?
View 1 RepliesHas 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?
What I would like to do is make an abstract class that will hold objects in a dictionary and manage the adding/deleting/key changes of those items in the dictionary. My problem is that in order to make the class as generic as possible I declared the dictionary as dictionary(of long, of SomeInterface).The problem is when I try to pass a strongly typed dictionary in the constructor using dictionary( of long, ClassThatImplementsSomeInterface) I get a compiler error because it cannot convert to that type.
The reason I want to pass the dictionary in the abstract class's constructor is so that I can use the strongly typed dictionary in the subclass and have the abstract class manage the keys when it needs to. So how can I do something like this? Also- If there is a much better way to manage keys than what I am doing feel free to let me know, but I am much more interested in how to make this work since I have encountered this type of problem a few times before.
Here's the abstract class:
Public MustInherit Class HasChildrenKeys
Protected m_childItems As Dictionary(Of Long, IHasKey)
[code].....
I have a solution with multiple projects, some of the projects are written in VB, some in C#. I am wondering if there's a way to use interfaces and/or enums written in VB in C# classes? My C# code below doesn't compile, however I am able to see the interface in intellisense.
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P.S It's a console/service application, not ASP.Net (where I know it's doable).UPD: Sorry guys, was missing a reference to the project with the interface. It's fixed now. I think the thing that in VB projects references are done slightly different than in C# confused me.
I have a program written in Visual Studio to me 3 values ( 0-255, 0-255, 0-255) to send the serial interfaces, and While assigned to the 3 values of 3 sliders together.[code...]
View 1 RepliesSay I have a interface called IProperties and I have a collection called colMyProperties that is a collection of IProperties. Then I have an object called clsProperty that implements the IProperty interface. Now, in my code where I add objects to the colMyProperties collection I add a bunch of clsProperty objects. so far so good.
Now when I try to access an object in the collection I can only access properties and methods of the IProperties interface, not the clsProperty object. What am I doing wrong? Do I need to cast the object?
I have a project that has several different interfaces (a website, a local application, and some webservices), that all use the same class library. The library is an API to a database. Some settings, like log level, database connection etc, i want to store in a single place, and I want them editable. What is the best way to accomplish this? I am concerned both about ease of editing, and ease of access for the dll, as there will be a lot of calls to it and a lot of lookups for the values. I have considered using app.config, a standalone XML file, and writing values to the registry, but I cannot find any good comparisons.
View 2 RepliesI have three classes which implement an Interface iComparesWith, and I wish there to be a single function such that each iComparesWith object of any of the three implementing classes should be able to compare itself with any other iComparesWith object, again, of any of the three implementing classes, and know if the two objects are equal. How can I code this so that the comparison code is only written once? Is it the case that I will have to create a top-level MustInherit class which implements the equality comparison, and have MustOverride methods for all of the methods of iComparesWith?
View 1 RepliesI am working on creating a customized UI composite control. This control would be a container to several other custom controls.As a first step, i am creating the container UI using a singleton pattern. This is because at any point in time only one isntance of this container is allowed to be created. This is fine.Now i want to practice interface based desgin. So i introduced a sinple interface calleD IdesignSurface which has two properties. I would like my singleton class to implement this interface,so i tried something like this and got an error saying "end of line
NotInheritable
Class DesignSurface
implements IDesignSurface
[code]......
I am a VB programmer of some 13 years. I started briefly with VB5 back in the mid-to-late 1990s, but then quickly moved to VB6 which I did for several years on PCs and HPCs (CE 1.x devices).I have done .NET 2002, 2003, 2005, and 2008 each for stints, intermingled with VB6 coding, at various jobs. But, I never got formally trained on VB.NET. In fact, I taught myself VB5/6 too. I have a degree in Computer Science and Mathematics, but the university CS program only had Unix systems. I basically learned everything I know on the fly from various Microsoft Press and other company's books (and the MS website/MSDN CDs too) while doing projects.I was wondering what everyone would suggest to really learn the .NET workings and why they are setup like that for Windows client/server applications. It doesn't have to be technical and brain-numbing.I have recently run into things dealing with MSFlexGrid vs DataGridView and how they link/work with database sources that confounds me. And, I am assuming there's just something I don't know about how/why VB.NET works the way it does...and I want to learn it to become a better developer.I want kind of that fun book that's easy to read, is thorough in that it teaches you a wide range of how to use/implement .NET controls/interfaces, and will fill in the gaps in my knowledge and experience.
View 1 RepliesWhen I pass an an object 'MyObject' which implements 'IMyInterface' to a method parameter declared as IMyInterface, I understand that this method parameter 'sees MyObject through the eyes of its interface'.
View 2 RepliesCan we call firewall an interface?
View 1 RepliesI have an interface called IBaselineControl. Now I'm trying to write a procedure which requires, as an argument, a Control which implements the IBaselineControl interface. However, I don't know the syntax for this. VB.Net allows us to require multiple interface implementations along with class inheritance when writing constraints for generic types. The syntax used there suggests that something like this might work:Public Sub Test(X As {Control, IBaselineControl})Unfortunately, that syntax doesn't work and I'm unable to find any syntax which does.
View 6 Replies