| Temporary variables still checked out ... [message #13210] |
Thu, 22 October 1998 00:00  |
Martin Schultz
Messages: 515
Registered: August 1997
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Senior Member |
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To all,
even after about an hour or so, I still cannot figure out why I
get the error message "% Temporary variables are still checked out -
cleaning up..." with the program attached below. The idea of the program
is to return a free logical unit number both as function result and
parameter so that it can be used immediately as well as later on
( like in OPEN_FILE,name,get_freelun(ilun) & free_lun,ilun ).
Interestingly, the result itself is correct, and if you first open a
file (e.g. with openr,1,name), then a subsequent call to get_freelun
yields no error message. I searched the online help but couldn't find
anything.
Thanks for any input,
Martin.
--
------------------------------------------------------------ -------
Dr. Martin Schultz
Department for Engineering&Applied Sciences, Harvard University
109 Pierce Hall, 29 Oxford St., Cambridge, MA-02138, USA
phone: (617)-496-8318
fax : (617)-495-4551
e-mail: mgs@io.harvard.edu
Internet-homepage: http://www-as.harvard.edu/people/staff/mgs/
------------------------------------------------------------ -------
; $Id: get_freelun.pro,v 1.1 1998/10/09 19:53:32 mgs Exp mgs $
;----------------------------------------------------------- --
;+
; NAME:
; GET_FREELUN (function)
;
; PURPOSE:
; Return next available logical unit number. Unlike
; the internal GET_LUN procedure, this function is not
; restricted to unit numbers above 100, and it will
; detect any blocked unit number.
;
; CATEGORY:
; I/O tools
;
; CALLING SEQUENCE:
; lun = GET_FREELUN([LUN])
;
; INPUTS:
; none
;
; KEYWORD PARAMETERS:
; none
;
; OUTPUTS:
; The lowest available logical unit number. This number is
; also returned in the LUN parameter for later use.
;
; SUBROUTINES:
;
; REQUIREMENTS:
;
; NOTES:
;
; EXAMPLE:
; openw,get_freelun(lun),filename
;
; MODIFICATION HISTORY:
; mgs, 17 Sep 1998: VERSION 1.00
;
;-
; Copyright (C) 1998, Martin Schultz, Harvard University
; This software is provided as is without any warranty
; whatsoever. It may be freely used, copied or distributed
; for non-commercial purposes. This copyright notice must be
; kept with any copy of this software. If this software shall
; be used commercially or sold as part of a larger package,
; please contact the author to arrange payment.
; The copyright is granted if this program becomes part of the
; IDL distribution.
; Bugs and comments should be directed to mgs@io.harvard.edu
; with subject "IDL routine get_freelun"
;----------------------------------------------------------- --
function get_freelun,lun
help,/files,output=list
newlun = 1
lun = newlun
; at least one file open
; find lowest available unit number
if (n_elements(list) gt 1) then begin
; maximum allowed number of open files exceeded?
if (n_elements(list) gt 99) then $
message,'Cannot handle any more open files'
; extract numbers and compare to expectation
for i=1,n_elements(list)-1 do begin
usedlun = fix(strmid(list[i],0,3))
if (usedlun gt i) then begin
newlun = i
lun = newlun
return,newlun ; this one's free
endif
endfor
; next free unit is greater than all used ones
newlun = i
lun = newlun
return,newlun
endif else begin ; no file opened
return,newlun
endelse
end
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| Re: Temporary variables still checked out [message #15481 is a reply to message #13210] |
Wed, 26 May 1999 00:00  |
Peter Mason
Messages: 145
Registered: June 1996
|
Senior Member |
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philaldis@geocities.com wrote:
<...> Every time I run it, if I hit the okay button,
> I get the message from IDL 'Temporary variables still checked out', or
> at least it's virtually like that, after the program exits.
<...>
> I don't know what's going on, but is it something to do with the
> structures and passing by value etc.
Phil, you're essentially doing your assignment to a temporary variable
when you do something like (structure.member)=val instead of
structure.member=val. The brackets tell IDL to evaluate their
contents, and this incurs the creation of a temporary variable. The
assignment is lost when the temp variable is destroyed, and you get that
inscrutable "programmer's revenge" error message in lieu of a warning
that something hasn't worked out quite as you might have expected.
> ((*(info.ptr)).optIndex)[i,*] = 0
=> Instead of this, try (*info.ptr).optIndex[i,*]=0; etc.
Things DO get a bit unsettling when (structures of) pointers to
structures are involved, but a bit of command line action will
normally clarify IDL's workings with brackets soon enough. (Basically,
you must restrict your bracketing to just the pointer component(s).)
There was quite a bit of discussion about all this
some time back (at least a year) on the NG. As I recall, Stein Vidar
pretty much sussed out how it all works - it may be worth your while
searching a news archive for this thread.
Peter Mason
--== Sent via Deja.com http://www.deja.com/ ==--
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