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Re: screwy system variables !? [message #6606 is a reply to message #6602]

Thu, 25 July 1996 00:00

thompson
Messages: 584
Registered: August 1991

Senior Member

landsman@sorbet.gsfc.nasa.gov (Wayne Landsman (301)-286-3625) writes:

> In article <4t714c$lf2@senator-bedfellow.MIT.EDU>, trujillo@xnmusc.mit.edu (Chad Trujillo) writes...
>> It seems like I can't actually create new system variables in a
>> function or program and use them later in that same function/program.
>> For example, I have the following program (in file tester.pro):
>> pro tester
>> defsysv, "!tester", 222
>> print, !tester ;this line directly refers to !tester
>> end

>> When I try to compile/run it, I get the following error (unless I
>> manually define !tester at the command line first):
>> % Not a legal system variable: !TESTER.

> You want to have all references to !TESTER in quotes so that the compiler
> won't reject the system variable before the DEFSYSV call is executed. One
> way to do this is as follows:

> pro tester
> status = execute('defsysv, "!tester", 222')
> status = execute('print, !tester')
> end

> Presumably you would want a short program that compiles the necessary
> system variables as the first procedure to be compiled.

> --Wayne Landsman landsman@sorbet.gsfc.nasa.gov

Another way to get around this problem is to put the call to DEFSYSV in your
IDL startup procedure (given by the environment variable IDL_STARTUP). That
way, it'll be guaranteed to be defined before you try to use it, and you won't
need to use calls to EXECUTE.

Bill Thompson

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[Message index]

		screwy system variables !? [2] By: trujillo on Thu, 25 July 1996 00:00
		Re: screwy system variables !? [2] By: chase on Thu, 25 July 1996 00:00
		Re: screwy system variables !? By: thompson on Thu, 25 July 1996 00:00
		Re: screwy system variables !? [2] By: peter on Fri, 26 July 1996 00:00

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