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Re: defsysv [message #7898 is a reply to message #7777]

Fri, 17 January 1997 00:00

Peter Mason
Messages: 145
Registered: June 1996

Senior Member

On Wed, 15 Jan 1997, Jeff Hall wrote:
> Why does this work on the command line
>
> IDL> defsysv, '!jeff', 38
> IDL> print, !jeff
>
> when this doesn't work as a pro?
>
> pro test
> defsysv, '!jeff', 38
> print, !jeff
> end

I think this comes down to another strange "feature" in the IDL compiler:
It seems that IDL recognises system variables at COMPILATION time.
In your routine, !jeff is undefined at compilation time; this is
detected and IDL stops with an error message on the line "print, !jeff".
(!jeff only gets defined at runtime.)

A sort-of way out is to have a routine which defines system variables but
doesn't do anything else with them, and call it before any routine which uses
these system variables is compiled.
More simply, define all of your custom system variables at IDL startup (e.g.,
in a startup file). Then you can reassign their values in your programs
(e.g., !jeff=38).

Peter Mason

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[Message index]

		defsysv By: Jeff Hall on Wed, 15 January 1997 00:00
		Re: defsysv By: Peter Mason on Fri, 17 January 1997 00:00

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