I haven’t seen that effect – I’ve certainly never encountered it being a bottleneck. Here’s a very rough-and-ready benchmark which shows (on my box anyway) delegates actually being faster than interfaces: using System; using System.Diagnostics; interface IFoo { int Foo(int x); } class Program : IFoo { const int Iterations = 1000000000; public int Foo(int … Read more
A function that takes a delegate as a parameter must use a named delegate type; unlike in Objective-C you can’t declare an anonymous delegate type inline in the function definition. However, the generics Action<> and Func<> are provided so that you don’t have to declare a new type yourself. In the code below I’m assuming … Read more
A number of classes are unavailable as generic contraints – Enum being another. For delegates, the closest you can get is “: class”, perhaps using reflection to check (for example, in the static constructor) that the T is a delegate: static GenericCollection() { if (!typeof(T).IsSubclassOf(typeof(Delegate))) { throw new InvalidOperationException(typeof(T).Name + ” is not a delegate … Read more
Instead of inducing performance overhead, why not use an extension method to alleviate both problems: public static void Raise(this EventHandler handler, object sender, EventArgs e) { if(handler != null) { handler(sender, e); } } Once defined, you never have to do another null event check again: // Works, even for null events. MyButtonClick.Raise(this, EventArgs.Empty);
The only difference between weak and assign is that if the object a weak property points to is deallocated, then the value of the weak pointer will be set to nil, so that you never run the risk of accessing garbage. If you use assign, that won’t happen, so if the object gets deallocated from … Read more
At this line : gameAddViewContoller.delegate=self; Notice that self is of type ViewController which does NOT conform to the GameAddViewController protocol.
Personally I use a couple of different patterns: [Task][State]Handler – UITaskFinishedHandler [Event]Handler – ControlLoadedHandler [Function Name]Delegate – DoSomeWorkDelegate – used when I need to create a delegate for calling a function on a different/new thread [Task]Callback – ContainerLoadedCallback – used when control A starts an action which control B does most of the work and … Read more
How about extending the Stopwatch class? public static class StopwatchExtensions { public static long Time(this Stopwatch sw, Action action, int iterations) { sw.Reset(); sw.Start(); for (int i = 0; i < iterations; i++) { action(); } sw.Stop(); return sw.ElapsedMilliseconds; } } Then call it like this: var s = new Stopwatch(); Console.WriteLine(s.Time(() => DoStuff(), 1000)); … Read more
The answer to this question lies in how C# Controls work Controls in Windows Forms are bound to a specific thread and are not thread safe. Therefore, if you are calling a control’s method from a different thread, you must use one of the control’s invoke methods to marshal the call to the proper thread. … Read more
First of all, your two examples are doing two totally separate things. The first is declaring a generic delegate variable and assigning a value to it, the second is just defining a delegate type. Your example, more completely, would be: public static class Program { // you can define your own delegate for a nice … Read more