I'm writing a Cocoa API for a project and the API takes a delegate. The protocol that I came up with declares all the methods as optional, but why would I do that instead of just documenting the delegate methods in a header file and taking a plain id as a parameter? ...
When trying to use delegates in C# to solve a problem in a functional way, I've come across a pitfall that I want to share resp. for which I would like to hear your suggestions. Background I want to fill a grid from a list of objects where the values for single columns are get using delegates (idea borrowed from Philip Pipers ObjectLis...
My friend is primarily a VB developer and he says time and time again how much more simple it is to code events in VB than C#. My take on the issue is that it probably is easier but if there was not a reason for the added complexity, they probably would have made it just as simple in C#. Can anyone tell me if there is any added flexibili...
public sealed class FtpManager { public event EventHandler LoggingIn = delegate { }; private void OnLoggingIn(object sender, EventArgs e) { var handler = LoggingIn; handler(sender, e); } // ... } In the above code, I have initialized LoggingIn event handler with an empty delegate. Will that affect memory...
The .net EventHandler is limited to Templates that inherits from EventArgs. How is that done? The implementation (Got to refference in vs) shows the following code: [Serializable] public delegate void EventHandler<TEventArgs>(object sender, TEventArgs e); But i think TEventArgs is just a name. How can I write a typed delegate that is...
I have some extra functionality i need to add which includes adding a new property to an object and extending methods in another class that handles this object. I'm dealing with source code of a product (in C# 2.0) we use which i really don't want to modify, i just want to extend on it. I'd ideally like to have a separate assembly to d...
I have a sequence of functions that look very similar but for a single line, like the following two (but I have many more of them): private static int HowManyHoursInTheFirstYear(IList<T> samples) { DateTime firstDate = samples[0].Date; int count = 0; while (count < samples.Count && samples[count].Date.Year == fir...
I am trying to load an image in the background and then update the UI. I have been playing with this all day and I don't know what I am missing. I keep getting the following error: "The calling thread cannot access this object because a different thread owns it." I've hunted around following example after example, but I cannot se...
When i do val = dict["nonexistent key"] i get System.Collections.Generic.KeyNotFoundException Is there a way i have my dictionary call a member function with the key as a param to generate a value? -edit- Maybe i should of been more specific. I want to AUTOMATICALLY call a member function to do what it needs create the proper value for ...
Hi I'm learning about Events / Delegates in C#. Could I ask your opinion on the naming/coding style I've chosen (taken from the Head First C# book)? Am teaching a friend about this tomorrow, and am trying to come up with the most elegant way of explaining the concepts. (thought the best way to understand a subject is to try and teach ...
Hi, I am trying to create a delegate (as a test) for: Public Overridable ReadOnly Property PropertyName() As String My intuitive attempt was declaring the delegate like this: Public Delegate Function Test() As String And instantiating like this: Dim t As Test = AddressOf e.PropertyName But this throws the error: Method 'Pub...
Several times I've seen ReSharper generate code that looks like this: delegate void myHandler(int i); myHandler myHandlerContainer; ... foreach (Delegate @delegate in myHandlerContainer.GetInvocationList()) {...} Does the '@' in @delegate give that variable any special semantic meaning? Or is it just a convention I didn't encounter be...
There are some Delegates predefined in C# I know these: EventHandler // Default event callbacks EventHandler<T> // Default event callbacks with custom parameter (inheriting from EventArgs) Action // Function without return value and without parameter Action<T1, T2, T3, T4> // Function without return value and 1-4 parameters Func<T1, T2...
Hi, I think know how to do this in C# but I'm having syntax trouble in VB.NET because I need to take advantage of the 'handles' event stuff. I have different events that I somehow (probably delegate) need stored in a property of an attribute (I just add an attribute to a property linking to the corresponding event). E.g. <BindEvent(E...
I would like to create a delegate and a method that can be used to call any number of Web services that my application requires: Example: public DateCheckResponseGetDate(DateCheckRequest requestParameters) { delegate object WebMethodToCall(object methodObject); WebMethodToCall getTheDate = new WebMethodToCall(WebServices.GetTh...
It is not possible to inherit from System.Delegate or System.MulticastDelegate in C#. It is perfectly possible to do it in MSIL as long as you declare standard 'runtime managed' methods. However, every time I am adding a 'cil managed' method to the type, I am getting: System.TypeLoadException: Illegal definition for runtime implemented ...
Hi all, Here's my old code from WinForms: private void ValueChanged(double inValue1, double inValue2) { //only manual mode for this driver, so that's easy. if (ValueLabel.InvokeRequired) { ValueLabel.Invoke(new MethodInvoker(delegate { ValueLabel.Text = (inValue1* inValue2/ 1000).ToString...
In the following example, I want to define a System.Action which executes a specific method that I define at runtime, but how do I pass the method name (or the method itself) so that the Action method can define the delegate to point to that particular method? I'm currently getting the following error: 'methodName' is a 'variable' but...
So what I'm trying to do is call a single propertyWasSet() function when any property within a C# class is set (conversely, propertyWasGot() when it is get). I would also like to know which property's 'get' was invoked. I would like to maintain a dictonary of properties that are 'set', and check upon the 'get' action if they have been s...
I've seen time and time again API (particularly in the .NET framework) that uses Func<TObject, bool> when Predicate<TObject> is seemingly a perfectly responsible option. What good reasons might an API designer have for doing so? ...