Re: forcing variable definition in IDL?

[davidf(at)dfanning.com (David Fanning)]

Gernot Hassenpflug (gernot-nospam@kurasc.kyoto-u.ac.jp) writes:
 
> So, my question: is it possible in IDL 5.4 to force definition of
> variables, or at least to automate a variable-check in IDL.

It is certainly possible to "force" a variable to
have a certain definition. That's not the problem.
The problem is making it *stay* a certain definition.
That, in general, is not possible in IDL, since IDL
has dynamic typing capability.
> 
> Alternatively, maybe I need to write a function that automatically
> checks the first use of a variable in a program. I have used the
> routine_info and routine_names functions to obtain information 
> about variables in scope at the time.

You can check. But like recalcitrant children, they
will be doing something else the minute you turn
your back. :-)

> Does anyone know of either how to get IDL to check variables'
> definition,
> or how to write a function to do that?

   IDL> theType = Size(variable, /Type)

Or, if you prefer the type "name":

   IDL> theTypeName = Size(variable, /TName)
 
> I have also toyed with the idea of using each variable as a single-
> element array (eg. b(0) = 1), but that is most inelegant and lengthy.

Don't bother. IDL scalars *are* single element arrays:

   IDL> a=5
   IDL> a[0] = 6 & Print, a

Cheers,

David
-- 
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
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