Passing events between different classes

[Tom]

This is probably a really basic question, but I know someone will be
able to help me. I have a single object A that contains a hash of
objects B. Each object B contains its own TCP client object containing
a connection to a server somewhere.

There is also a completely separate hash of objects C at the same
place as Object A. When I get TCP data into the TCP client I need to
let all of the object C's know about it. I Was wondering if I could
have all of the C objects register for the B events?

Tom

[Peter Duniho]

On Mon, 16 Jul 2007 12:26:13 -0700, Tom <ku****@gmail.c omwrote:

This is probably a really basic question, but I know someone will be
able to help me. I have a single object A that contains a hash of
objects B. Each object B contains its own TCP client object containing
a connection to a server somewhere.

There is also a completely separate hash of objects C at the same
place as Object A. When I get TCP data into the TCP client I need to
let all of the object C's know about it. I Was wondering if I could
have all of the C objects register for the B events?

Is object A at all relevant? You didn't mention it with respect to the
communication between the objects B and objects C, so for the moment I'm
essentially (mostly) ignoring your first paragraph.

Anyway, yes...you can have each object C subscribe to an event on each
object B if you like. Every time an object C is instantiated, it would
have to subscribe to every object B's event, and every time an object B is
instantiated, each object C would need some way to know so that each can
subscribe to the new object B's event.

You may want to consider a "mediator"-based design, in which there's an
intermediate class that handles the connections between objects C and
objects B. Perhaps this is object A, or maybe you will want to make
another object to do this. You don't provide enough specifics for anyone
else to suggest which is better, so you'll have to decide that for
yourself.

The way the mediator would work is that objects C would all subscribe to a
single event on the mediator, while the mediator would subscribe to each
of the objects B event. Then when the mediator receives the event raised
by any object B, it would forward that event to its own event, which would
automatically result in each object C receiving the event.

This way each object C only needs to deal with a single object (the
mediator) and does not need to concern itself with the instantiation of
new objects B, while each object B would only have a single object (the
mediator) subscribed to its own event. Also, it encapsulates the
management of dealing with instantiations of each object B into a single
class (a nice way to do that would be to make the object B class aware of
the mediator, and register itself when it's instantiated, providing a
method in the mediator that in turn subscribes the mediator to the object
B event).

Pete

[Ignacio Machin \( .NET/ C# MVP \)]

Hi,
"Tom" <ku****@gmail.c omwrote in message
news:11******** **************@ 22g2000hsm.goog legroups.com...

This is probably a really basic question, but I know someone will be
able to help me. I have a single object A that contains a hash of
objects B. Each object B contains its own TCP client object containing
a connection to a server somewhere.

There is also a completely separate hash of objects C at the same
place as Object A. When I get TCP data into the TCP client I need to
let all of the object C's know about it. I Was wondering if I could
have all of the C objects register for the B events?

You could do so, but then you will have to let each C instance know of every
B objects.

A better approach might be if A is the one that subscribe to B's and then A
will iterate in C's.

btw, how you are keeping receiving info from all those B's instances?

[Tom]

Thanks Peter,

This has really clarified everything for me, I guess I was just used
to doing things a certain way...

Thanks again,
Tom

[Tom]

I am feeling very frusturated about this right now. The part that is
frusturating is the:

// When the Publisher instance calls this, the Mediator
subscribes
to its event
public void Register(Publis her publisher)
{
publisher.TheEv ent += _MyHandler;
}
I have moved my mediator class to the utilites namespace of our
project. Both classes that need to use the mediator are in different
namespaces, but both use the utilities namespace. So that is great
and all until I get to the Register function. Based on the previous
example, show above, it looks like it needs to know about the
Publisher class. Is there a way to get around it having to know about
the publisher class? Since all my classes are USING ProgramUtils;, I
feel it would be improper to have USING MainProgram; in the utils?

Tom

[Peter Duniho]

On Thu, 26 Jul 2007 13:18:05 -0700, Tom <ku****@gmail.c omwrote:

[...] Based on the previous
example, show above, it looks like it needs to know about the
Publisher class. Is there a way to get around it having to know about
the publisher class?

You can do it a couple of ways:

1) Have a Publisher base class that the actual publisher class
inherits. The Publisher base class would be declared with the Mediator
class, while the actual publisher class can be declared anywhere, and the
Mediator and subscribers need not even know the actual publisher class.

2) Have a Publisher interface that the actual publisher class
implements. See above.

Pete

[Tom]

On Jul 26, 4:22 pm, "Peter Duniho" <NpOeStPe...@nn owslpianmk.com>
wrote:

On Thu, 26 Jul 2007 13:18:05 -0700, Tom <kuh...@gmail.c omwrote:

[...] Based on the previous
example, show above, it looks like it needs to know about the
Publisher class. Is there a way to get around it having to know about
the publisher class?

You can do it a couple of ways:

1) Have a Publisher base class that the actual publisher class
inherits. The Publisher base class would be declared with the Mediator
class, while the actual publisher class can be declared anywhere, and the
Mediator and subscribers need not even know the actual publisher class.

2) Have a Publisher interface that the actual publisher class
implements. See above.

Pete

That seemed to work great. Thanks Again!!

Tom