How to use EventArgs

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Guest

when i double-click on a button on a form as i am designing the form, the IDE
creates a method corresponding to a event assignment as follows:

this eventhandler: this.exitToolStripMenuItem.Click += new
System.EventHandler(this.exitToolStripMenuItem_Click);
is paired with: private void exitToolStripMenuItem_Click(object sender,
EventArgs e) {}

How do/Can I what the EventArgs are?
 
Amil said:
when i double-click on a button on a form as i am designing the form, the
IDE
creates a method corresponding to a event assignment as follows:

this eventhandler: this.exitToolStripMenuItem.Click += new
System.EventHandler(this.exitToolStripMenuItem_Click);
is paired with: private void exitToolStripMenuItem_Click(object sender,
EventArgs e) {}

How do/Can I what the EventArgs are?
Click to expand...

If you search your MSDN help for "EventArgs", you'll find (among others) an
article entitled "EventArgs Class" to get you started. From that page your
can link to "EventArgs Members", "Events Tutorial" and "Eventhandler"
topics.
 
Amil,

In this case, the EventArgs will not do anything for you. The reason
for this is that there is no extra information associated with the event
that you can't get from the sender parameter (which is the button that fired
the click).

The EventArgs instance is there so that you can observe the pattern laid
out for event signatures by MS when they created the framework. The pattern
basically is (and I'm sure you have seen this everywhere):

object sender; <EventArgs derived type> e

With .NET 2.0, this pattern is even more useful. The reason for this is
that there is now delegate covariance (I believe that is it), which means
that if you have a delegate that is expecting a signature of:

object sender, CancelEventArgs e // CancelEventArgs derives from EventArgs

You can assign a method with a signature of object, EventArgs to that
delegate, because it is possible to cast down the CancelEventArgs to an
EventArgs instance. This will allow you assign event handlers to more
delegates (depending on the logic you need to execute).

Hope this helps.
 
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