| Re: undefined keyword variables [message #17615 is a reply to message #17531] |
Mon, 01 November 1999 00:00   |
davidf
Messages: 2866
Registered: September 1996
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Senior Member |
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Craig Markwardt (craigmnet@cow.physics.wisc.edu) writes:
> As to David's suggestion to define default values, that's not always
> feasible. What about the POSITION keyword? If it's not defined then
> you want to rely on IDL's standard positioning. No default should be
> required!
I think it is not only feasible, but required, that you
provide default values for *any* variable you plan
to use in the code. Certainly if I were planning to
use the POSITION keyword I would have something like this:
IF N_Elements(thePosition) EQ 0 THEN thePosition=!P.Position
...
Plot, data, Position=thePosition
As for keywords that come in with _Extra, well, that's
what God made the Catch statement for. :-)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
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