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Re: Arg_Present, XSurface, and Other Assorted Blunders [message #9708]

Fri, 08 August 1997 00:00

davidf
Messages: 2866
Registered: September 1996

Senior Member

Kirt Schaper writes in response to my longish article:

> I might be missing something here, but it seems to me that 'arg_present'
> is doing precisely what it is supposed to do, report whether the
> variable passed to it is (1) an argument to the current routine AND
> (2) a variable into which a value will be copied when the current
> routine exits. If the user called the routine w/o specifying the a
> value for "data", then there is NO way that any value assigned to a
> variable "data" w/in the routine. (This is assuming that they did not
> pass in an unassigned variable as a keyword parameter.)
>
> 'Arg_present' is intended to allow avoiding computation of output
> variables if the calling routine has no way of retrieving those values.

Yes, I am pretty clear now about its rather limited usefulness.
My point is exactly this: its *name* implies things about it that
are not true. Hence, it is likely to be misused by unwary programmers
like me.

Cheers,

David

------------------------------------------------------------ ---
David Fanning, Ph.D.
Fanning Software Consulting
Customizable IDL Programming Courses
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com

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		Re: Arg_Present, XSurface, and Other Assorted Blunders By: davidf on Fri, 08 August 1997 00:00
		Re: Arg_Present, XSurface, and Other Assorted Blunders By: Kirt Schaper on Fri, 08 August 1997 00:00

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