I appreciate that similar questions have been asked before, but I am struggling to invoke the Linq Where method in the following code. I am looking to use reflection to dynamically call this method and also dynamically build the delegate (or lambda) used in the Where clause. This is a short code sample that, once working, will help to fo...
Hi, I feel like I'm so close to working this out and have read dozens of articles and existing questions. I have a method like this: public T DoStuff(object arg1, object arg2) { /* Do stuff and return a T */ } And I need to be able to pass this method to another class for callback purposes. However, when this other class calls bac...
I've been doing some work lately on a project that makes extensive use of events. One of the things that I need to do is asynchronously call multiple event handlers on a multicast delegate. I thought the trick would be to call BeginInvoke on each item from GetInvocationList, but it appears as though BeginInvoke doesn't exist there. Is t...
I am trying to implement the delegate Pattern in Objective-C, however I am experiencing a Bad Access exception when invoking the delegate sometimes. It seems this is caused by the delegate being released. Apple does not recommend to retain delegates. How can I check my delegate if is still valid before trying to send it a message? ...
If you are in a method and you pass in an anonymous delegate, does the 'return' key word return a value for the anonymous delegate, or does it return the function? I know in ruby, they use 'next' to achieve this type of functionality inside of a block. Here's an example: public bool X() { AList.Where(x => { if (x.val ==...
As i can perform asynchronous operations using delegates,i suspect there is a thin chance to use System.Threading in my application.Is there any essential situation where i can not avoid System.Threading ? ( Just I am in learning Phase). Example : class Program { public delegate int Total (int a,int b); static void Main() { Tot...
here code delegate void CheckNewsDelegate(); void CheckNews() { frmNews news = new frmNews(); news.Show(); } CheckNewsDelegate dlg = new CheckNewsDelegate(CheckNews); dlg.BeginInvoke(null, null); new form not create normal. how fix it? ...
I have a problem that is surely familiar to many: I'm making a call (to be specific it is Forest.GetCurrentForest()) which, in some circumstances, will fail to work and throw an exception. Not a huge problem, just catch it and deal appropriately. However the call, when it fails, is very slow; it takes 30 seconds to fully finish. I w...
When i implement WaitCallback waitCB = new WaitCallback(DisplayTime); for (int i = 1; i <= 5; i++) { ThreadPool.QueueUserWorkItem(waitCB, null); Thread.Sleep(2000); } public void DisplayTime(object state) { Console.WriteLine("Current Time {0} ", DateTime.Now); } ( 1 ) Does it mean ,my job is queued into to ...
All examples in Qt show that one should use delegate classes to provide editors that reside within QTreeView (QListView, etc). I want to have a separate non-modal dialog to edit item's attributes. Should I use delegate classes to do so? That is, no editing or special behavior is required within QTreeView. ...
Edit: Moved the actual question to the top. Update: Found an example by Microsoft, tucked on some more code at the end. My questions are these: Is it safe to call multiple BeginInvoke calls on the same delegate instance, or do I have to construct a new delegate instance for each in-flight method call? If I have to construct new insta...
I have app delegate.h & .m files linked to a Main.Nib. Nib has a window and a tabbar controller which has 4 navigation controllers. Each of these 4 do their own thing inside 4 more Nib's containing tableview controllers etc. The tableview controllers take their data from arrays manipulated in the app delegate. All work fine and i hav...
Been doing this for a while but haven't noticed I have been using a "new" each time I remove an event handler. Am I supposed to be creating a new object? Basically is there a difference between 1 and 2? (1)ethernetdevice.PcapOnPacketArrival -= new SharpPcap.PacketArrivalEvent(ArrivalResponseHandler); (2)ethernetdevice.PcapOnPacketArri...
What is the reason why I can't put parenthesis after my Method name when assigning it to a delegate type. Here is code: public delegate Simple Simple(); //Create a delegate that returns its own type. class Program { public class Exercise { public static Simple Welcome() { Console.WriteLine("Welcome!...
In the following delegate example, how does the compiler infer what type the variable alpha is? delegate double Doubler(double x); public class Test { Doubler dbl = (alpha) => //How does it determine what type is alpha? { return alpha * 2 }; Console.WriteLine(dbl(10)); //Is it when the method is called? int he...
I have a method with an out parameter, and I'd like to point an Action or Func (or other kind of delegate) at it. This works fine: static void Func(int a, int b) { } Action<int,int> action = Func; However this doesn't static void OutFunc(out int a, out int b) { a = b = 0; } Action<out int, out int> action = OutFunc; // loads of comp...
I have a protected method in a base class which accepts a Func<T> and then turns around and executes with some added goodness. Example usage: public MyResponse DoSomething(MyRequest request) { return base.Execute(() => this.Channel.DoSomething(request)); } What I'm looking to do is take the func delegate instance and redirect the ...
Can anyone tell me if there a way to see if an action contains any code? Action x = new Action(()=> { }); should return false, while Action x = new Action(()=> { var x = "i am a string" }); should return true. Perhaps using reflection? ...
I may have gone crazy... but 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...
Situation: C#, .NET 3.5, WinForms Objective: Form1 has a Button that can be enabled via the constructor. I.E. the button will only be shown if I call new Form1(true). We'd like to be able to pass a method via some param from Form2 to Form1 (doesn't have to be on Form1's constructor), and when Form1.Button1 is pressed, Form2.<SomeMethod...