Event Properties - C# Discussion Boards

7-Sep-03 9:02

I'm looking into event properties, and I've found that there's very little out there that discusses them. Why? It seems that they are very useful.

Anyway, with event properties, you can do custom handling of the addition and storage of event delegates. It would seem that you can also do custom handling of the invocation of those delegates. Is this correct? In my case, I'm wanting to stop invoking event delegates when a Handled property in the event's EventArgs is set to true.

Also, I heard that event properties are slower than normal events. Why is this? Is there a way to minimize/get around this?

Thanks in advance!

"Blessed are the peacemakers, for they shall be called sons of God." - Jesus

"You must be the change you wish to see in the world." - Mahatma Gandhi

leppie7-Sep-03 9:24

7-Sep-03 9:24

What are you talking about?

Those add/remove accessors for events?

leppie ::AllocCPArticle("Zee blog");
Seen on my Campus BBS: Linux is free...coz no-one wants to pay for it.

J. Dunlap7-Sep-03 9:30

7-Sep-03 9:30

Yes. They're called event properties, because they have accessors just like properties.

"Blessed are the peacemakers, for they shall be called sons of God." - Jesus

"You must be the change you wish to see in the world." - Mahatma Gandhi

leppie7-Sep-03 9:44

7-Sep-03 9:44

OK, just wanted to know if it wasnt something I have not ever seen or heard about Smile | :)

ANyways. The C# compiler allows one to define an event in a "shorthand" format, ie the way we all use. Behind the scenes however, the compiler does this:

Your input:

event EHandler MyEvent;

Compilers ouptut:

private EHandler MyEvent;

event EHandler MyEvent
{
  add
  {
     this.MyEvent = ((EHandler) Delegate.Combine(this.MyEvent, value));
  }
  remove
  {
     this.MyEvent = ((EHandler) Delegate.Remove(this.MyEvent, value));
  }
}

This can be easily seen in Reflector.

leppie ::AllocCPArticle("Zee blog");
Seen on my Campus BBS: Linux is free...coz no-one wants to pay for it.

J. Dunlap7-Sep-03 9:55

7-Sep-03 9:55

Thanks for the info. Smile | :)

What I don't understand is:

* Why would this type of event be slower?

MSDN says: "Note that event properties are slower than event fields, as each event delegate has to be retrieved before it can be invoked. "

But wouldn't the cost of retrieval be minimal?

* Would I be able to handle the invoking of the delegates myself? Since I have access to each delegate, this shouldn't be too hard.

* In order to do what I'm wanting to do, I would have to call each of the delegates separately, rather than combining them and calling them together. What are the performance costs of this?

"Blessed are the peacemakers, for they shall be called sons of God." - Jesus

"You must be the change you wish to see in the world." - Mahatma Gandhi

leppie7-Sep-03 13:06

7-Sep-03 13:06

jdunlap wrote:
Why would this type of event be slower?

Too small to notice

jdunlap wrote:
Would I be able to handle the invoking of the delegates myself? Since I have access to each delegate, this shouldn't be too hard.

No problems here either Smile | :)

jdunlap wrote:
In order to do what I'm wanting to do, I would have to call each of the delegates separately, rather than combining them and calling them together. What are the performance costs of this?

Multicast delegates are stored as a linked list. By defining a property, one can use a different container such as a hashtable, array, arraylist or some other ingenious datasource (SQL/XML).

leppie ::AllocCPArticle("Zee blog");
Seen on my Campus BBS: Linux is free...coz no-one wants to pay for it.

J. Dunlap7-Sep-03 16:18

http://www.codeproject.com/csharp/scrframework.asp[^]

7-Sep-03 16:18

OK, thanks for the info! Big Grin | :-D

"Blessed are the peacemakers, for they shall be called sons of God." - Jesus

"You must be the change you wish to see in the world." - Mahatma Gandhi

Screen Saver

Ivan Vasic7-Sep-03 6:27

Ivan Vasic

7-Sep-03 6:27

How can I make my project (which result is .exe file) to be a screen saver (I think extension is .scr) ???

Re: Screen Saver

cduced7-Sep-03 6:57

cduced

7-Sep-03 6:57

A question about c#

S^nyp7-Sep-03 5:42

S^nyp

7-Sep-03 5:42

Can anyone tell me what is different about c# compared to visual c++ 6 and does the c# enviornment use the .net framework... if so what are some disadvantages and advantages to it + I'm new to c# and wondered will it be the future of visual c++ 6 and maybe replace mfc?? Please I would appreciate any responses.

<marquee>Universal Project... Soon to be a .net

Re: A question about c#

Alvaro Mendez8-Sep-03 9:38

Alvaro Mendez

8-Sep-03 9:38

Snyp wrote:
what is different about c# compared to visual c++ 6

One is a .NET language, the other a development tool which uses Microsoft's C+ compiler and has support for MFC.

Snyp wrote:
does the c# enviornment use the .net framework

Yes, of course. C# is a .NET language.

Snyp wrote:
what are some disadvantages and advantages to it

Some advantages of C#:
- syntactically very similar to C/C++/Java.
- simpler than C/C++ -- no need to deal with pointers and memory management.
- code written in C# can be used and extended by other .NET languages.
- has a few features not found in C/C++/Java, such as Properties.

Some disadvantages of C#:
- Some C++ features, such as multiple inheritance, default parameters, preprocessor macros, and templates (which are coming soon) are not there.
- Garbage collection scheme may not be suitable for some real-time, performance critical apps.

I hope to have shed some light on your doubts. Several people have brought up this issue in other forums, such as the Lounge. I recommend you do a Search on the topic to help you decide your direction.

Regards,
Alvaro

Hey! It compiles! Ship it.

simple question - Windows Services

SHenin7-Sep-03 5:37

SHenin

7-Sep-03 5:37

Definition from MSDN for interactive processes:

"Interactive Processes
- A service that can communicate with the desktop."

Does that mean if a "Win32OwnProcess" or a "Win32SharedProcess" is not an "InteractiveProcess", some sort of mechanism prevents that process from interacting with Desktop.

I just wrapped up some code in Windows Services - didn't configure it specifically as interactive process, but when I query ServiceController object, it tells me that it's an Interactive Win32OwnProcess. My service does nothing more than listening on a Tcp port and spits out a block of byte in return when connection is accepted. Any client can interact with desktop in response to the byte sent out by my Windows Service. Is that what makes it "Interactive"?

Thanks.

can't finalize an object which holds a System.Timers.Timer

MeisterBiber7-Sep-03 2:53

MeisterBiber

7-Sep-03 2:53

Hi !

Can anybody please help me?!

I have an object which holds a System.Timers.Timer .

Unfortunately the GC doesn't collect the Object when the timer is running.

any ideas what I can do?!?

thanks.
andi

Re: can't finalize an object which holds a System.Timers.Timer

leppie7-Sep-03 3:53