[AccessD] Doin the class thing - the class side.

OK, let's discuss what is going on.

clsDNDText is a class which I call an object wrapper.  It wraps an access
object (a text box in this case) and then uses event sinks to service the
events of the wrapped object.  So this class wraps a text box.  Notice in
the header of the class the line:

Private WithEvents mtxt As TextBox

This dimensions a text box variable private (cannot be seen outside of the
class) and informs VBA that the class will be sinking events (the
WithEvents keyword).

Next we have a constant which holds the text "[Event Procedure]"

Private Const cEvProc As String = "[Event Procedure]"

It is good programming practice to as much as possible have a class self
contained, not depending on outside resources to perform its function.

Next we have termination code.  When a class unloads it calls its terminate
event if one exists.  In this case it simply "unhooks" the text box,
setting the pointer to nothing.  We do that because it is possible to
prevent a form from closing when objects on the form have pointers to them
that are not cleaned up.

Private Sub Class_Terminate()
    Set mtxt = Nothing
End Sub

We then have an Init function which is public, and allows us to pass in a
pointer to a text box.  mInit then stores that pointer in our class header.
 This allows the class to sink any and all events for the passed in object
(text box).  Notice that we immediately place the cEvProc into the
OnDblClick property of the text box.  It is a little known fact that it is
the very existence of that text in the property that causes VBA to start
raising events for the object.  By specifically placing that code in that
property in our code, we do not need the developer to double click the
property for us.  In this case we have only hooked the OnDblClick event
however we could add others by adding a similar line of code for other
events.

Function mInit(ltxt As TextBox)
    Set mtxt = ltxt
    mtxt.OnDblClick = cEvProc
End Function

And finally, the guts of the thing, the very reason for doing all this, we
have the event sink itself.  This code is entered when the event fires for
the specific text box which this class instance wraps.  IOW if we have
several instances of this class, one for TextBox 2, TextBox4 and TextBox6,
then when you double click in TextBox4, the event in the instance servicing
that text box will sink the event and do something with it.  In this case I
am simply poppigg up a message box to display the name of the control.

Private Sub mtxt_DblClick(Cancel As Integer)
    'Do something here
    MsgBox mtxt.Name & ".DblClick"
End Sub

John W. Colby

Reality is what refuses to go away
when you do not believe in it