Events, Delegates And Interfaces - What To Declare In The Interface
Apr 30, 2012
I have ended up with the following event structure in a custom control - it seemed to be the recommended way for my scenario in MSDN (though it wasn't easy to follow!) This is the MSDN page I used,MSDN - How to: Implement Events in Your Class.
[code]...
What now has me totally confused (even more so than I was about setting up the above pattern) is what to declare in the Interface? I wanted to declare the event in the interface since there will be several other classes that do similar things and they need to be used interchangeably (hence an Interface in the first place) and if I've gone down the Interface route it seems smart to make sure the 'minimum' content that each class will have to implement declared in the Interface...
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May 2, 2012
I'm having trouble porting some .NET2-era C# to .NET2-era VB.NET. Specifically, I am trying to define an interface that an ASP.NET user control will implement.(For background, I am trying to re-implement Phil Haack's Model-View-Presenter example from several years ago: http://haacked.com/archive/2006/08/09/ASP.NETSupervisingControllerModelViewPresenterFromSchematicToUnitTestsToCode.aspx)
The C# interface I'm working from defines properties and events (IsPostBack, Load) that are already implemented by the base control.However, VB.NET is forcing me to explicitly implement these properties/events in the user control (Public Property IsPostBack() As Boolean Implements IView.IsPostBack...). I'd like to just define these in the interface and not have to do anything special in the code-behind of the implementing user control.I'm assuming that I can do this in VB.NET, I just don't know how. I've spent all sorts of time googling/bing-ing, and haven't come up with the answer.
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Feb 11, 2010
What is the difference b/w Delegates and Events. I have little bit confusion. Where delegates are used, and when we have to used delegates. Can, you give some examples(both delebates and events) in vb.net.
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Nov 29, 2009
is there a way to create an interface of delegates? Sub dostuff(byval arg1 as dele1)works, problem is that i have 8 delegates, so i will have to give it 8 signatures. that isn't so bad, but the problem is that when there are various combinations of signatures it gets real real bad.
Sub dostuff(byval arg1 as [Delegate])works, but it allows me to accept delegates beyond the 8 that i wanted (it's like declarign arguments with base Object)could i be able to do this:
Sub dostuff(byval arg1 as Idele1to8)
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Mar 17, 2010
I am using AddHandler to wire a function to a control's event that I dynamically create:
[Code]...
This code is generating a run-time exception stating: Unable to cast object of type 'MyEventHandlerDelegate' to type 'System.EventHandler' What am I not understanding about System.Delegate even though AddHandler takes as an argument of type "System.Delegate"? What Type does "EventHandler need to be to cast to a type that AddHandler can accept?
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Oct 1, 2009
I am hoping there is a way to do this.I have a base class that has event handling in it. My console application is running my workflow. Part of that workflow is to raise events at specific intervals in a separate thread to broadcast the workers' current state (a heartbeat I have heard many call it).
I also have another program in the same solution that is a windows form that I want it to be able to listen to what is going on in the console application so that it can display the worker states. I have tried running both at the same time and verified the events are triggering, but the monitor is not finding any of the raised events.
I am fearing that there is no way to do this, and I will need to go to a database logging method or something else... but in the off chance someone knew how to communicate between applications with event (or event-style) logic, I would appreciate it.Currently the applications are running from the same location. The goal is that the monitor application will eventually be attached with a broadcaster for our network so that our workstations can monitor for certain worker states without being logged into the machine and the main monitor will show us the full status of all the workers.
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Oct 13, 2011
I'm working on learning VB.Net after having programmed in VB6, VBA, and VBScript for several years. I'm assuming that something that begins with the letter I is an interface. However, a lot of places I see people/documentation referring to what appears to be class objects that begin with I. I guess I'm under the impression that Interfaces are contracts that class objects can agree to.
[Code]...
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Feb 7, 2011
I want to declare a property as an interface collection of an interface, and I want to instanciate the explicit type later, in the constructor. Something like this.
Public Class LicenseFile
Implements ILicenseFile
Public Property Collection As IList(Of ILicenseFileDataNode)
[Code]....
In short, the question is "Why It Didn't work"? This is a simplified scenario, but It's easy to take a workarround, But I need understand the reason because It's fails.
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Oct 21, 2009
I'm dealing a problem in implementing interface for multiple class.
Assuming I have a class named Class Unu .
I created an interface called Test for those 2 classes.
The first class Unu has 2 data members(i=12 and j=12.17). When you run the program it stores the result on screen 24.17
The second class called Doi has 2 data members(a=20 and b=32.17).
What I want now is to do the same thing for data members a and b so that it stores on screen 20+32.17=52.17
My problem is that I want to be displayed also the result for the 2 data members for the second class on my screen. I implemented the interface on class Doi but I cannot see why he isn't displaying me the second result 52.17.
What I must add to my code to do that?
Here's the full code:
CODE:
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Jun 25, 2010
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.
[Code]...
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Oct 31, 2009
I have made dll component and it contains interface. I am executing it in form. The problem is that i would like to use some variables in the form, but I do not like to declare them in there. Is it possible to declare them in this dll interface and then use them in form?
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Nov 21, 2009
I need set events on a class library and catch them in an form.
For example, I run a sub in the dll and I need "receive" the event that the sub in the class is running.
The dll is creted by me in vb, but i don't know how raise events on it to be catched in the form.
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Dec 3, 2011
I just can't, im guessing something's not enabled, but what?
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Feb 2, 2012
creating a COM component Instance like this for supporting multiple version of COM components
Creating Instance
Private _cmObjct As Object
Public Property CreatingInstances() As Object
Get
[code]....
at the same time how to declare this method without referenced dll SSDP is an interface so how to declare this interface for my usage is this Correct ...?
Error: Dim d as Object = Activator.CreateInstance(Type.GetTypeFromProgID("SecureTronics.SSDP"))
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Nov 24, 2009
Ran into this while converting a VB.NET interface to C#; the VB version defines an event which doesn't conform to the typical (object sender, EventArgs e) signature:
[Code]...
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Mar 27, 2009
What are Delegates and Multicast Delegates in VB.NET? How do I use them? provide a simple example to illustrate the concept.
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Feb 10, 2010
I have a class that I want to be serializable but contains a public instance of delegate that, apparently can't be serialized: [Code] Is there a way to make it serializable however?
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Feb 3, 2012
Consider these two functions[code]...
My question is: what is the right way to accomplish this to resolve the ambiguity so that I can pass value or references types and get overload 2, but pass Functions and get overload 1? Can I constrain the types in some way to make this happen?
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Mar 27, 2011
I've been tinkering with Delegates, and now Multicast delegates. Every time I invoke two delegates It only displays one of the two delegates per invocation.
[Code]...
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Feb 17, 2011
[Code]....
So func is a function that accepts a string and return a string. In practice, internally, func also utilizez text1, text2. In fact, func can even be a member function with access the object that owns it (something like me or this operator).
And all that can be accomplished without changing the signature of func? How do the compiler do this?
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Dec 15, 2010
I am struggling to get the syntax for the reflection call GetCustomAttributes ... at least I don't seem to be able to get hold of the custom attribute which I've decorated a particular method with. The complicating factor maybe that I have passed that method into an extension method as a generic delegate. (The other, more likely, complicating factor is that I'm not sufficiently familiar with reflection or what happens when you pass a method as a parameter like this!)
The code appears to run, and when I step it, the count returned from the GetCustomAttributes is 1. I can't work out how to get hold of that custom parameter
[Code]...
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Apr 7, 2009
Is it possible to create anonymous delegates in vb.net version 8 or earlier? If so, could someone provide an example of the syntax?
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Jul 12, 2011
I have a VBNET app to scan my Active Directory using WMI calls and return some basic informaiton such as Dell Model name, current user logged on, Dell Service Tag etc my issue is the app becomes unresponsive whilst it scans and i have to wait for it to finish looping before i can work with it, in the past a do events used to suffice
I think Multithreading is the way i may need to go, whats the best approach? I tried to use Delegates but it doesnt seem to have made any difference
below is my for next loop code that calls the functions, the last section "Private Sub Button1_Click" down is the Delegate code i attempted
[Code]...
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Nov 15, 2010
Maybe I am just not reading the MSDN documentation correctly, but given a function that takes in one string parameter and returns type T, how can this be specifed as a shared function using Func()?
MSDN says Func(Of In T1, Out TResult), but all of their examples use the same data type, i.e., Func(Of String, String). I want to do Func(Of In String, Out T), where T is arbitrary (but I can constrain it if necessary by a base class). I want it shared/static at the class level, yet the encapsulating class will itself not be a generic class. It seems in this specific scenario, it's impossible to do what I want because the compiler would have no way of knowing what Type T is at runtime.
So is it possible to do generics on delegates or anonymous lambda expressions in VB.net (not C#)?
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May 7, 2009
I can come up with, if I understood the solution better, I could probably phrase a better subject line.[code]...
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Jun 4, 2010
I am having trouble with getting a delegate to work properly.Here's my
[Code]...
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May 26, 2009
I was going through tutorials and found the topic of Events and Delegates. However, I fail to understand why should this be required ? Instead of having to raise events, can't one just call the necessary procedure ?Sorry for posing this basic question. Any replies or even links to existing posts are welcome. [Also not sure if this question strictly falls under VB.NET category.]
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Oct 13, 2011
I have been trying to implement the jQuery weekcalendar using .net. What I can't seem to figure out is why weekcalendar states events.events is undefined after I make an ajax call to a webmethod I created which returns JSON. Below is the relevant code:
[Code]...
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Aug 2, 2009
I want to make Keybord events and mouse events for learning and educational Purpose.
1. In Form any object like A "picture box" move by Arrow keys .
2. Picture Box Contain many Picture i want change Picture With next and Previos By Arrow keys.
3. I contain Voice of alphabet in Mp3.When i Press any button in textbox then its work.
4. Mouse Pointer Change My Own.
5. I click any Object or any thing By mouse its noice clicking sound like Tik Tik Tik.... Question No 3 is very hard to do . but not im possible
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Oct 16, 2009
Are Interfaces used often? Need opinions.
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