[dba-VB] OT: VB.Net - general questions

John,
 
Take a look at this article:
 
http://www.vbdotnetheaven.com/Code/Apr2003/009.asp
 
Basically, the System object exposes an Exception object that many of
the other framework classes extend.  I am not sure if there is a named
object for a "missing collection exception", but if you look at the
article it explains how to hande the select case type of exception traps
that you are talking about.
 
 
Gary Ray - Application Developer
Workforce Information Systems R & D
E-Mail gray at utah.gov

>>> jcolby at colbyconsulting.com 07/14/03 12:16PM >>>
I am porting my SysVars class to VB.Net just as an exercise.  Of course
I
use the error handler insertion wizard for Access, but VB.Net has the
new
Try/catch error handling (which I very much like BTW).  But it does
mean
that no port is trivial since I have to remove all the OnError / resume
kind
of stuff in every function.

In my old code I have a case statement where I accumulated the various
errors that could occur, and once handled a resume next would take me
back
into the code.  that obviously has to change but I'm a little confused
as to
what it will change to.  For example I have code that attempts to add
an
object to a collection:

    mcolObjNames.Add(strObjName, strObjName)

There could be two problems here, the first is that no collection has
been
instantiated yet, the second is that the object is already in the
collection.  Thus a select case would be nice, which was how the old
error
handler in Access worked.

Select case err
    case XXX
    case YYY
    Case else
end select

Now we have:

Try

    mcolObjNames.Add(strObjName, strObjName)

Catch e as XXXX (FIRST PROBLEM - WHAT IS xxxx?)
    Handle error here
Finally

End Try

It certainly looks like e could be used in a select case statement. 
However
to do so I need the equivalent of the "resume next".


AND FINALLY...

In access I also used a label for the exit such that all exiting code
could
go through the exit point for cleanup of pointers etc.  The books I
have
don't ever show such a construct.


John W. Colby
www.colbyconsulting.com 


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