.net - Using Reflection For Generically Typed Delegate And Interfaces?
Aug 24, 2009
I have a bunch of classes that each have a property called Sequence. This property is implemented from an interface called ISequenced. For this example lets call one of these classes A. When I have a List(of A), I want to be able to sort them using the standard List.Sort(addressof delegate) where the delegate is a standard function that takes in two ISequenced objects and compares their sequence numbers and returns a boolean flag, rather than declaring a function for each individual class that implements ISequenced.
E.g.
Dim li as List(of A) = GetValues()
li.Sort(addressof SortBySeq)
...
Public Function SortBySeq(ByVal ob1 as ISequenced, ByVal ob2 as ISequenced) as
[Code]...
How would I declare the function in order to do this (if it is even possible in VB.NET?
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Jan 8, 2010
I have the following code compiles without issue. Of course, I get an invalid cast xception when executing the Dim C As IDoThingsC = GetThing_C(). Am I missing something?Would you ever want to return an object that does not meet the interface requirement for a function return value?
Public Class ClassA
Public Sub DoThings_A()
Debug.Print("Doing A things...")
[code].....
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Jan 30, 2010
from the documentation we have this: Multicast Delegate: Represents a multicast delegate; that is, a delegate that can have more than one element in its invocation list.
so am i right to say that Multicast delegate is no different from a normal delegate other than the fact that it has arguments. so System.Action is a 'normal' delegate whereas System.Action(T)(Byval obj as T) is a multicast delegate?
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Feb 9, 2010
I've created a Delegate that I intend to call Async.
[Code]...
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Jun 1, 2010
Code:
Public Class SendPings
Shared Sub New()
AddHandler Post.Saved, AddressOf Post_Saved[code].....
I get a error" Method 'Private Shared Sub Ping(item As BlogEngine.Core.IPublishable, itemUrl As System.Uri)' does not have a signature compatible with delegate 'Delegate Sub WaitCallback(state As Object)'.
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Jan 7, 2010
Is there a way to write a single routine that could enumerate a list regardless of the data type? I am trying to write a custom XML serialization class and it would be great if I could enumerate all items in a generic list the same way, regardless if it was of type String, Integer, etc.
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Aug 23, 2011
In a program that I'm responsible for, we want to start keeping track of milestones. These milestones are quite simple and consist of a unique identifier, the project they're assigned to, a description, and a date that they should be accomplished by (or not, if there's no concrete due date).We use a slightly modified Model-View-Presenter architecture, and currently I'm passing this list around through the presenters, but it seems fairly clunky, so I was wondering:What's the best way to make this list available to all the presenters/views that need it?We're using VB.NET 3.5, and I was toying with the idea of making this a shared property of the main presenter, but it does seem like that adds some unnecessary coupling.
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Apr 20, 2012
I am writing ASP.Net Web-form in VB.
I have a system which have already handled exceptions by try-catch blocks everywhere.How do I quickly and generically implement exception logging like overriding something instead of inserting logging functions in every single catch block?
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Mar 23, 2010
I am trying to write a VB.NET alternative to a C# anonymous function.I wish to call Threading.SynchronizationContext.Current.Send which expects a delegate of type Threading.SendOrPostCallback to be passed to it. The background is here, but because I wish to both pass in a string to MessageBox.Show and also capture the DialogResult I need to define another delegate within. I am struggling with the VB.NET syntax, both from the traditional delegate style, and lambda functions.My go at the traditional syntax is below, but I have gut feeling it should be much simpler than this:
Private Sub CollectMesssageBoxResultFromUserAsDelegate(ByVal messageToShow As String, ByRef wasCanceled As Boolean)
wasCanceled = False
[code].....
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Aug 9, 2009
I create one typed dataset by dataset designer in VS2008. How can I change this dataset to shared typed dataset?
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Oct 16, 2009
Are Interfaces used often? Need opinions.
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Mar 13, 2009
I 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?
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Dec 30, 2011
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.
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Aug 6, 2009
Im 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?
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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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Sep 12, 2009
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].....
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Oct 20, 2011
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.
[Code]...
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.
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May 1, 2009
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...]
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Nov 14, 2010
Say 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?
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Oct 4, 2011
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.
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Dec 8, 2009
I 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?
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Jul 5, 2010
I 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]......
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Aug 25, 2011
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.
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Apr 21, 2010
When 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'.
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May 8, 2010
Can we call firewall an interface?
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Nov 3, 2010
I 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.
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Mar 13, 2011
Is is possible to implement a type specifier with 2 interfaces in .net? Something like:
Public Sub New(obj as ICollection and INotifyCollectionChanged)
''Initialize Code
End Sub
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Apr 22, 2011
I have a Delphi written DLL that exposes some interfaces to a vb.net application.
The interfaces inherit from IUnknown (but this could be changed if required), simplified example:
IWindow = interface(IUnknown)
['{E9A11D0B-8A05-4CBA-83FA-C5CC6818DF6E}']
function GetCaption(var Caption: PChar): HRESULT; stdcall;
end;
[Code]....
Now I want to transfer a collection of IWindow to vb.net, and in the vb.net application I want to be able to loop through it with a for in loop.
I read that it's possible using IEnumerable/IEnumerator but I don't quite understand how to implement them. Are there any good tutorials about this, specifically showing the declarations on both side? Example code would be great.
Please note that I prefer not create a com dll that should be registered and imported. Currently I export a function that enabled me to obtain an interface.
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Oct 17, 2011
how to do something that seems that it should be simple.
I tried it on a larger project I'm working on and got an error, so I reduced it to the simplest possible that I could find:
Public Interface IF1
Event WakeUp(ByVal TheObject As Object)
End Interface
[Code]....
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Apr 9, 2009
I just started playing around with interfaces recently and I have a couple things I want to ask. First off I always understood that an Interface cannot contain code, you are merely creating almost a "template" of methods, property's etc...Lets say I have this:
Public Class MyTest
Implements IMyTest
Public Sub iDispose() Implements IMyTest.iDispose
[code].....
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