I recently created a Silverlight 3 app in which I created some UI elements in the code behind and added them at run-time dynamically.
I was hoping to just use the built-in MouseButtonEventArgs or the sender object to get a reference to the instance that was clicked, however I noticed once I started that this was not the case. I was not able to access any properties of the object that triggered the event and program against it.
void myFunc(object sender, MouseButtonEventArgs e)
{
//Can't do this :(
sender.someProperty = someValueToUpdate;
//or this
MyClass foo = sender as MyClass;
foo.someProperty = someValueToUpdate;
}
I ended up just writing a CustomEventArgs object to pass an instance, but it surprised me that this wasn't a default behavior.
Can anyone shed some light as to WHY the sender object doesn't contain a reference to the object that triggered the event?
Also, here is what I did to get that instance.
myObject.myEvent += new CustomEvent(myFunc);
...
void myFunc(object sender, CustomEventArgs e)
{
e.MyProperty = someValueToUpdate;
}
...
public class MyClass
{
public MyProperty = 0;
public event CustomEvent myEvent;
protected virtual void MyEventMethod(CustomEventArgs e)
{
if (myEvent != null){myEvent(this, e);}
}
public MyClass ()
{
this.MouseLeftButtonDown += new MouseButtonEventHandler(this_MouseLeftButtonDown);
}
void rect_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
CustomEventArgs e2 = new CustomEventArgs(this);
MyEventMethod(e2);
}
}
public class CustomEventArgs : EventArgs
{
private readonly MyClass myProperty;
public CustomEventArgs(MyClass myProperty) { this.myProperty = myProperty; }
public MyClass MyProperty { get { return myProperty; } }
}
public delegate void CustomEvent(object sender, CustomEventArgs e);