Re: Question about events and object arrays

From: Peter Krikelis (PeterKrikelis_at_discussions.microsoft.com)
Date: 12/07/04 

Date: Tue, 7 Dec 2004 11:51:02 -0800

Nicholas,

Thank you for the info. The reason was that I was experimenting making as
dum linear data structure and thats why I needed the indices, but as Bruce
Wood suggested, I might be better off using the HashTable class.

I am new to C# and OOP and I am just getting my hands dirty, thats all.

Thanks,

Pete.

"Nicholas Paldino [.NET/C# MVP]" wrote:

> Peter,
>
> In this situation, I would recommend that you give the object some sense
> of the index that it is at. For example, when you assign it in an array,
> you would assign a property indicating the index in the array it is at.
>
> However, I can see where people would cringe at this.
>
> You might want to consider having a wrapper for the array which exposes
> the event. The EventArgs-derived class would have an index on it,
> indicating the index of the item that fired the event, and the sender would
> have the actual object.
>
> I'm curious though, what do you need the index of the item in the array
> for if you have the sender?
>
>
> --
> - Nicholas Paldino [.NET/C# MVP]
> - mvp@spam.guard.caspershouse.com
>
> "Peter Krikelis" <PeterKrikelis@discussions.microsoft.com> wrote in message
> news:9F9A9622-54B8-4C93-B500-F0ADB6CC67E6@microsoft.com...
> > Nicholas,
> >
> > Thanks for the clarification.
> >
> > However, is there another way of doing that? The reason I ask is because
> > if
> > you have an array of a 100,000 objects theoretically, then looping through
> > the entire array would be expensive. Compund it with the fact that the
> > events
> > are happening fairly quickly and in repeated succession.
> >
> > Is there a way of passing a handle of the specific array object to the
> > class
> > that raises the event handler, and return that handle with the event data?
> >
> > Thank you,
> >
> > Pete.
> >
> >
> > "Nicholas Paldino [.NET/C# MVP]" wrote:
> >
> >> Peter,
> >>
> >> Yes, I do. I assume the event handler has access to the original
> >> object
> >> array. In this case, enumerate through each of these elements in the
> >> array,
> >> comparing the object reference (use the static ReferenceEquals method on
> >> object to be sure) to the sender.
> >>
> >> --
> >> - Nicholas Paldino [.NET/C# MVP]
> >> - mvp@spam.guard.caspershouse.com
> >>
> >> "Peter Krikelis" <PeterKrikelis@discussions.microsoft.com> wrote in
> >> message
> >> news:5412E712-02B6-4099-8446-B0D579F791F6@microsoft.com...
> >> > Nicholas,
> >> >
> >> > I think you were the one to point me to the paradigm of event handlers
> >> > in
> >> > the first place. I did that.
> >> > My event handler now takes arguments of "sender" type object and
> >> > "derivedEventArgs" which derives from System.EventArgs.
> >> >
> >> > What I was looking for is how to compare object references or cycle
> >> > through
> >> > that array. Do you mean using a for loop?
> >> >
> >> > Thanks,
> >> >
> >> > Pete.
> >> >
> >> >
> >> >
> >> > "Nicholas Paldino [.NET/C# MVP]" wrote:
> >> >
> >> >> Peter,
> >> >>
> >> >> Yes, there is. Since you would be using one event handler for all
> >> >> the
> >> >> items in the array, you can cycle through the array and then compare
> >> >> object
> >> >> refrences with the sender of the object (this is assuming you followed
> >> >> the
> >> >> pattern for event handlers, where the first parameter is the object
> >> >> that
> >> >> fired the event, the second is of type EventArgs or derived from
> >> >> EventArgs.
> >> >> Don't worry, I'll wait while you make the changes. Done? Ok =) ).
> >> >> Once
> >> >> you do that, you will have your index.
> >> >>
> >> >> Hope this helps.
> >> >>
> >> >>
> >> >> --
> >> >> - Nicholas Paldino [.NET/C# MVP]
> >> >> - mvp@spam.guard.caspershouse.com
> >> >>
> >> >>
> >> >> "Peter Krikelis" <PeterKrikelis@discussions.microsoft.com> wrote in
> >> >> message
> >> >> news:8DAC6909-8D89-4029-9430-68FEF6392645@microsoft.com...
> >> >> > Hi,
> >> >> >
> >> >> > Finally figured events and delegates whew! Thanks to the people in
> >> >> > this
> >> >> > community that helped me out.
> >> >> >
> >> >> > So now I have a class that raises an event.
> >> >> >
> >> >> > Now if I instantiate an object array of that class, and the event
> >> >> > fires,
> >> >> > is
> >> >> > there any way of getting the array index of the object that raised
> >> >> > that
> >> >> > event?
> >> >> >
> >> >> > Thanks in advance.
> >> >> >
> >> >> > Pete.
> >> >>
> >> >>
> >> >>
> >>
> >>
> >>
>
>
>

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