TMG-L Archives

Archiver > TMG > 2002-11 > 1036939822


From: Allen Mellen <>
Subject: [TMG] v 5 Filters, logic, and updates
Date: Sun, 10 Nov 2002 09:50:22 -0500


In a recent message joanna asked "Is it too late to request REAL boolean
filters?"
I replied that these are indeed REAL Boolean filters.

In an off-list message I have been reminded that the logic built into TMG
filters employs a limited subset of what we have come to think of as
Boolean logic and that the filter logic lacks capabilities of SQL statements.

Nevertheless, the filter logic built into TMG is potentially very
powerful. Since we do not yet have the List of People and the capability
of setting flags via Secondary Output, some of that power remains
potential. (As Lee has pointed out, we don't know whether the List of
People "in the pipeline" will include secondary output when we first see
it, although my guess is that it will.)

The filters for people (now saved with the FLP extension) were completely
redesigned between v5.03 and v5.04. That redesign is one of the reasons
more than two months elapsed between v5.03 and v5.04. I have no special
knowledge, but I suspect that v5.05 will be released a lot sooner than two
months from now, especially since, as Lissa implied, there will be at least
one other upgrade after that before we have all the reports.

Two of the features that have been mentioned to me as missing from filters
are the lack of NOT and the fact that you cannot create expressions that
require two or more adjacent parentheses to get the evaluation order
correct. In fact there are, or will be after we get the List of People,
ways to use filters that require both of these.

For NOT, unless the condition is already built into an operator, the method
requires using the List of People to set a flag for the positive condition,
and then, in a second filter testing for the flag not being set.

For double parentheses, the simplest way to add dummy conditions that
produce everybody and connect them to the other conditions with OR One
dummy condition you could use is simply ID# > 0 .
If adding dummy conditions takes you past the limit of eight conditions,
you'll have to wait for the List of People and use a flag.

Allen

Allen Mellen -- New York, NY and Heart Lake, Susquehanna County, PA
permanent email address:<>
http://www.geocities.com/allenmellen
http://www.geocities.com/allenmellen/tmg.html


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