Find() will find the element that matches the predicate that you pass as a parameter, so it is not related to Equals() or the == operator. var element = myList.Find(e => [some condition on e]); In this case, I have used a lambda expression as a predicate. You might want to read on this. In … Read more
It’s often awkward to return values from events. In practice, I’ve found it much easier to include a writable property on a set of custom EventArgs that is passed to the event, and then checked after the event fires — similar to Cancel property of the WinForms FormClosing event.
The delTest() form is a compiler helper, underneath it is really a call to Invoke().
The first version is effectively doing: Action tmp = () => _myMessage = “hello”; var action = new Action(tmp); The problem you’re running into is that the compiler has to know what kind of delegate (or expression tree) the lambda expression should be converted into. That’s why this: var action = () => _myMessage=”hello”; actually … Read more
You generally make class protocols weak to avoid the risk of a “strong reference cycle” (formerly known as a “retain cycle”). (Note, we now do that by adding the AnyObject protocol to a protocol’s inheritance list; see Class-Only Protocols; we do not use the class keyword anymore.) Failure to make the delegate weak does not … Read more
Delegates send messages to you. For example: if you use the accelerometer delegate, you will get messages about the accelerometer. If you use that new neutrino-detection delegate, you will get messages about any neutrinos detected in the area. If you use PopUps, PopUps send you messages. And the way that is done, is with the … Read more
As others have posted, you can’t exit the loop in ForEach. Are you able to use LINQ? If so, you could easily combine TakeWhile and a custom ForEach extension method (which just about every project seems to have these days). In your example, however, List<T>.FindIndex would be the best alternative – but if you’re not … Read more
They’re not predefined in C#. They’re defined by the framework. The Action and Func delegate families are wider than you’ve shown – they go up to Action<T1, T2, T3, T4> and Func<T1, T2, T3, T4, TResult> Another common-ish one in .NET 2.0 for list manipulation (before LINQ) is Predicate<T>. For working with threads: ThreadStart ParameterizedThreadStart … Read more
public static Delegate CreateDelegate(this MethodInfo methodInfo, object target) { Func<Type[], Type> getType; var isAction = methodInfo.ReturnType.Equals((typeof(void))); var types = methodInfo.GetParameters().Select(p => p.ParameterType); if (isAction) { getType = Expression.GetActionType; } else { getType = Expression.GetFuncType; types = types.Concat(new[] { methodInfo.ReturnType }); } if (methodInfo.IsStatic) { return Delegate.CreateDelegate(getType(types.ToArray()), methodInfo); } return Delegate.CreateDelegate(getType(types.ToArray()), target, methodInfo.Name); }
When in doubt, check the docs! Basically, delegation is a way of allowing objects to interact with each other without creating strong interdependencies between them, since this makes the design of your application less flexible. Instead of objects controlling one another, they can have a delegate which they send (or delegate) messages to, and the … Read more