[AccessD] Why use UDF function as listbox RowSourceType??

Jim Dettman jimdettman at verizon.net
Tue Jun 24 13:58:07 CDT 2014


  It harkens back to a time when compact on close was not an option, so many
developers were loath to do anything with temp tables (of course, you can
always open a temp DB, but it was extra work).

  The other thing is that it allowed you to pull data from multiple sources
easily and then combine them.   I can't think of the last time I used a
callback function for a combo or list box.

Jim. 

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Bill Benson
Sent: Tuesday, June 24, 2014 12:07 PM
To: accessd at databaseadvisors.com
Subject: [AccessD] Why use UDF function as listbox RowSourceType??

This is sitting untouched on another list. Any takers here?

> I have been following the documentation here and here
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> http://msdn.microsoft.com/en-us/library/office/ff821440(v=office.15).aspx
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> http://msdn.microsoft.com/en-us/library/office/ff845731(v=office.15).aspx
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> and trying to understand why someone would want to do this, rather than
creating a temp table with the results of whatever is used to get the
values.
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> What I do not like about the method - aside from it being inordinately
complex and to me, non-intuitive (though I eventually got it) - is that it
is called again and again while the user scrolls the listbox, which slows
down the application.
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> Why do great programmers use this technique?
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> (I have seen code for example by Wayne Phillips at EverythingAccess.com
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http://www.everythingaccess.com/tutorials.asp?ID=Accessing-detailed-file-inf
ormation-provided-by-the-Operating-System
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> where he uses classes to wrap the functions to grab file properties from
windows explorer, and when he lists the results he uses a callback udf
structure similar to that shown in the above links).
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> Is there some compelling reason to do it this way, rather than a temp
table?
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