openr and /get_lun

[Craig Markwardt <craigmnet(at)cow.physics.wisc.edu>]

I have noticed that the use of /GET_LUN and ERROR keywords to openr is
not as helpful as I would have hoped.  Do other have this experience?
The problem is that when an error occurs, it is hard to know whether
the file unit was "gotten" or not.

For example:

pro test1
  openr, unit, filename, /get_lun, error=err
  free_lun, unit
end

If there was an error, then it is possible that UNIT was never set,
and is hence undefined.  FREE_LUN doesn't take undefined variables.

If there is error checking to do, I don't know exactly what it should
be.  So I find myself explicitly doing this instead:

pro test2
  get_lun, unit
  openr, unit, filename, error=err
  free_lun, unit
end

Comments?

Craig

-- 
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Craig B. Markwardt, Ph.D.         EMAIL:    craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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