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Re: keyword_set bug or feature [message #4214 is a reply to message #4212]

Fri, 12 May 1995 00:00

peter
Messages: 80
Registered: February 1994

Member

Phil (phil@peace.med.ohio-state.edu) wrote:
: Thanks to those who responded to my ? concerning common blocks.

: I just can across another 'feature' and was wondering if others felt
: that it is really a 'bug' or if there is some way to over come it. It
: has to do with keywords in functions or procedures. I use several and
: check to see if the are set using

: IF NOT(keyowrd_set(key)) THEN BEGIN
: ;set a default value here
: ENDIF

: The problem comes in if the user wants to set key = 0. If so then it
: appears to the above test that the keyword is not set even though in
: the function call the user typed
:
: Result = somefunction(var,key=0)

: What gives? Can I just add key = key + 1 and key = key - 1 around the
: testing if statement?

This is the specified behavior of keyword_set, and yes, it has caused
problems for others (i.e. me!). The solution to your problem is to
used n_elements(key) to test whether any value was set, or no value
at all. n_elements will return 0 on an undefined variable, and 1
on any scalar, including 0.

Peter

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[Message index]

		Re: keyword_set bug or feature By: chase on Mon, 15 May 1995 00:00
		Re: keyword_set bug or feature By: rivers on Sat, 13 May 1995 00:00
		Re: keyword_set bug or feature By: peter on Fri, 12 May 1995 00:00

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