[AccessD] Class Rebuttal was: Basic Unbound Form ...

True, but it works either way.

Drew

-----Original Message-----
From: John W. Colby [mailto:jwcolby at colbyconsulting.com]
Sent: Tuesday, June 13, 2006 11:58 AM
To: 'Access Developers discussion and problem solving'
Subject: Re: [AccessD] Class Rebuttal was: Basic Unbound Form ...


It still doesn't have to be global though.

Private mMyClass As MyClass

Function cMyClass() as MyClass
	set cMyClass = mMyClass
End function

Now it is global without anybody in the world able to (for example) "clean
it up" by setting the pointer to null.

I actually use this kind of thing for a "messaging" system internal to the
application.

A message class:

Public Event Message(varFrom As Variant, varTo As Variant, _
                        varSubj As Variant, varMsg As Variant)
Public Event MessageSimple(varMsg As Variant)

Function Send(varFrom As Variant, varTo As Variant, _
                varSubj As Variant, varMsg As Variant)
    RaiseEvent Message(varFrom, varTo, varSubj, varMsg)
End Function
Function SendSimple(varMsg As Variant)
    RaiseEvent MessageSimple(varMsg)
End Function

By instantiating the class, anyone can send a message and anyone (class) can
receive a message.

In a module:

Private mclsMsg as clsMsg

Function cMsg as clsMsg()
	if mclsMsg is nothing then
		set mclsMsg = new clsMsg
	endif
	set cMsg = mclsMsg
End function

Then someone sends a message:

	cmsg.SendSimple "Hello there"

Anyone sinking messages on this message channel now receives this message.

Or sends an "email type" message

	cmsg.Send "frmClaim", "frmAccounting", "Claim Payment", "Some
payment data"

Everyone on the channel receives the message and tests to see if the message
is for them, from someone they want to receive messages from etc.

And of course any class can sink an event so it doesn't even have to be a
form which receives the message.  And of course, because the message is a
variant, anything including a pointer to a form or pointer to a control can
be sent to the receiving class.

I use this to pass a control to a calendar form, so that the calendar form
can return the data directly back to the control.  The calendar listens on a
channel and anyone can open the form (modal), pass the control to have the
data placed in, and when control returns to the caller the control is
populated with the date.

JWC

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of DWUTKA at marlow.com
Sent: Tuesday, June 13, 2006 12:24 PM
To: accessd at databaseadvisors.com
Subject: Re: [AccessD] Class Rebuttal was: Basic Unbound Form ...

And where do you declare the object?

Let's say MyClass has an event.  Now I have three forms that need to see
that event.


Dim withevents MyClassObject as MyClass

That would go in the declarations, but how to you get all three forms to see
the same event? If each form had this in the Form Load event:

Set MyClassObject=New MyClass

Now each will see AN event when it is raised, but if form1 triggers the
event, it's going to get the event from it's instance of MyClass.  None of
the other forms will.  However, if MyClass was a global variable:

Public GlobalMyClass As MyClass

And the Load events had:

Set MyClassObject=GlobalMyClass

Now, when the event is triggered all three forms see the event.

Drew

-----Original Message-----
From: Charlotte Foust [mailto:cfoust at infostatsystems.com]
Sent: Tuesday, June 13, 2006 10:49 AM
To: Access Developers discussion and problem solving
Subject: Re: [AccessD] Class Rebuttal was: Basic Unbound Form ...


Huh?  What are you declaring globally?  You raise an event from the class
and sink it in the other objects.  What does a global have to do with that?


Charlotte Foust


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