Re: Consuming your own events.

the guideline clearly state that non-sealed classes that expose events should implement a:
protected virtual void OnTheEvent( EventArgs e ) for every public event.

I wuold strongly recomend any inheritor to override the OnTheEvent( ... ) instead of a
"lazy" +=. Through this override you can control ordering (as mentioned earlier) but
you can also cancel the event if required. The performance aspect can be neglected
since the invokation cost of a method and delegates are almost identical.
(prior to CLR2.0 there where a performance issue with delegate invocation)

regards,
  Daniel

________________________________________
From: Discussion of development on the .NET platform using any managed              language [[email protected]] On Behalf Of Greg Young [[email protected]]
Sent: Monday, January 28, 2008 11:30 PM
To: [email protected]
Subject: Re: [DOTNET-CLR] Consuming your own events.

I agree with Sebastien here ...but there is a problem that can be
introduced with ordering (when it is changed)... when do I need to tie
the event in order to be able to use it? With the overriden template
methods this problem doesn't exist.

On Jan 28, 2008 2:25 PM, Sebastien Lambla <[email protected]> wrote:
> > I've definitely fixed bugs in the last year by *removing* the event
> > handler and installing this pattern. The documentation does say
> > (somewhere) that for certain events such as Load, a class's behavior
> > will be undefined if it listens for the event on itself.
>
> This is not a CLR issue though, but a classlib design. If your class can
> have undefined behaviour if someone forgets to call the base class
> implementation, you either have a weak documentation or a weak
> implementation. Maybe both.
>
> >
> > -----Original Message-----
> > From: Discussion of development on the .NET platform using any managed
> > language [mailto:[email protected]] On Behalf Of Greg
> > Young
> > Sent: Monday, January 28, 2008 2:42 PM
> > To: [email protected]
> > Subject: Re: [DOTNET-CLR] Consuming your own events.
> >
> > Events are slower than a simple virtual method call ... also if there
> > is
> > an exception in another event handler your code is not guarenteed to be
> > called where as with the OnXXX pattern (event template methods) your
> > code will be called before the event is actually raised.
> >
> > On Jan 28, 2008 8:59 AM, Brady Kelly <[email protected]> wrote:
> > > I came across a mention in an article last year, advising on not
> > > consuming your own events, e.g. not using a Form_Load handler on your
> > > form, but overriding OnLoad.  What is the story behind this, and is
> > it
> >
> > > a UI thing I should ask about elsewhere, or a more general pattern?
> >
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