From bug-octave-request at bevo dot che dot wisc dot edu  Mon Oct 13 04:30:44 1997
Subject: empty lines in load file
From: fabian at olymp dot Umwelt dot TU-Cottbus dot de (Rolf Fabian)
To: bug-octave at bevo dot che dot wisc dot edu
Date: Mon, 13 Oct 1997 10:42:21 +0100

fabian at umwelt dot tu-cottbus dot de
topic: empty strings in load file

Hi jwe,

it's a great feature of octave to accept string matrices with variable
column length as variables. So, it's straightforward to write routines in
C-programs which parse streams/strings into line-oriented tokens and write
them into octave-formatted load files for further high-level treatment.
There's no problem, if you parse a simple example like
welcome="Hello\nWorld!\n"
which results in such an ascii loadfile newline characters, if '\n' are 
dismissed
--------------
# name: welcome
# type: string array
# elements: 2
# length: 5
Hello
# length: 6
World!
--------------
This works quite well as long as there are no empty lines in the parsed input.
If strings with empty lines are parsed e.g. welcome="Hello\n\nWorld!\n",
the logical output would be
--------------
# name: welcome
# type: string array
# elements: 3
# length: 5
Hello
# length: 0

# length: 6
World!
--------------
Such a load file seems to bring octave into big trouble!
Octave's respond to this loadfile is
:>error: load: failed to extract string length for element 2
:>error: ....

Moreover, if there are additional variables defined in the loadfile,
these errors prevents *ALL OF THEM* from beeing processed and loaded.
Of course, for an experienced programmer, it's quite easy to process the
input using whitespace to e.g. 
welcome="Hello\n \nWorld!\n" 
which removes the problem by writing a simple blank into the loadfile.

This might be considered as a 'feature', but we suggest a more consistent
treatment of empty strings in loadfiles. At least, such 'inconsistencies'
should be treated as 'warnings' - not as 'errors' -  in order to allow for
reading additional variables from the file.!

Best wishes
Dr. Rolf Fabian