Databases
StackOverflow2013
Postsdbo
PORaise event through a general method
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PORaise event through a general method
    primarykey
    data
    text
    <p>I'm trying to create a reusable method for a more complicated event execution. I can't get it to compile or run with framework events that don't follow the <code>EventHandler&lt;Type&gt;</code> pattern. I would like to avoid reflection if possible as it will be a heavily used event.</p> <p>I've created a test console app below which illustrates the problem:</p> <pre><code>using System; using System.Collections.Specialized; namespace CallEventsViaMethod { public class TestEventArgs : EventArgs { } class Program { static void Main(string[] args) { MyProgram program = new MyProgram(); program.Go(); Console.ReadKey(false); } } public class MyProgram { public event EventHandler&lt;TestEventArgs&gt; TestEvent; public event NotifyCollectionChangedEventHandler CollectionChangedEvent; public void Go() { TestEvent += new EventHandler&lt;TestEventArgs&gt;(MyProgram_TestEvent); CollectionChangedEvent += new NotifyCollectionChangedEventHandler(MyProgram_CollectionChangedEvent); // Want a reusable method I can use to conditionally execute any event GeneralEventExecutor.Execute&lt;TestEventArgs&gt;(TestEvent, new Object(), new TestEventArgs()); GeneralEventExecutor.Execute&lt;NotifyCollectionChangedEventArgs&gt;(TestEvent, new Object(), new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset)); } void MyProgram_TestEvent(object arg1, TestEventArgs arg2) { Console.WriteLine("Custom event ran"); } void MyProgram_CollectionChangedEvent(object sender, NotifyCollectionChangedEventArgs e) { Console.WriteLine("NotifyCollectionChangedEventHandler event ran"); } } public static class GeneralEventExecutor { public static void Execute&lt;T&gt;(EventHandler&lt;T&gt; eventToRaise, object sender, T eventArgs) where T : EventArgs { if (eventToRaise == null) return; Delegate[] registeredEventHandlers = eventToRaise.GetInvocationList(); foreach (EventHandler&lt;T&gt; eventHandler in registeredEventHandlers) { object target = eventHandler.Target; // Need access to the Target property // * Code deciding if should invoke the event handler * eventHandler.Invoke(sender, eventArgs); } } } } </code></pre> <p>Error messages are:</p> <blockquote> <p>error CS1502: The best overloaded method match for 'CallEventsViaMethod.GeneralEventExecutor.Execute(System.EventHandler, object, System.Collections.Specialized.NotifyCollectionChangedEventArgs)' has some invalid arguments</p> <p>error CS1503: Argument 1: cannot convert from 'System.EventHandler' to 'System.EventHandler'</p> </blockquote> <p>I understand why I'm getting the error, but can't figure out a way round it.</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USLee
    1. USLee
    plurals
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. COAren't you reinveinting the Event Aggregator?
      singulars
      1. PORaise event through a general method
      1. USWiktor Zychla
    2. COWhat the Execute method is doing in my production code is either Invoking the event normally, or invoking it via dispatcher, I was just trying to keep the code simple. I don't think the Event Aggregator would suffice in this case?
      singulars
      1. PORaise event through a general method
      1. USLee
    3. COLooks like it can't done without reflection: http://stackoverflow.com/questions/8407886/pass-event-as-parameter-to-a-method
      singulars
      1. PORaise event through a general method
      1. USLee
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload