[Changeset] Re: namelengthmax?

[David Bateman]

Bill Denney wrote:
> David Bateman wrote:
>> Since we're picking off the easy functions to implement that are matlab
>> core functions and not implemented in Octave, I looked at namelengthmax.
>> In matlab this is 63 which is basically limited by the string name
>> reserved for the variable name in matlab's "save" file format. However,
>> the same limits don't apply in Octave and the variable name length limit
>> is essentially "2^31-1". However when Octave writes to a mat-file it
>> truncates the variable names to 63 character (or 31 characters for v5
>> files).
>>
>> So if we implement namelengthmax should we return 63, or 2^31-1? Is this
>> function of any use in any case?
>>   
> My personal thoughts are that since we go for Matlab compatibility in
> almost all things and since it is not really useful for octave, we
> should have the function and it should have a warning similar to what
> you discuss above and then it should return 63.


Yeah that's what I thought.. See the attached patch..

> Have a good day,
> 
> Bill
> 
> P.S.  You're welcome to implement the hard ones, I was just going for
> the easy ones.  :)

Hey the easy ones are faster to implement, and you can't get much easier
than

function n = namelengthmax ()
  n = 63;
endfunction

There are still over 400 missing functions, so I'm sure we can't find
some other easy ones :-)

D.

# HG changeset patch
# User David Bateman <address@hidden>
# Date 1206311517 -3600
# Node ID ac4e70a647d1329fe9dadab32a5bc6c6ac8d761d
# Parent  35e6d57df330e64c57c044e6fe22d6c316344751
Add the namelengthmax function

diff --git a/scripts/miscellaneous/Makefile.in 
b/scripts/miscellaneous/Makefile.in
--- a/scripts/miscellaneous/Makefile.in
+++ b/scripts/miscellaneous/Makefile.in
@@ -39,7 +39,7 @@ SOURCES = ans.m bincoeff.m bug_report.m 
   fileattrib.m fileparts.m flops.m fullfile.m getfield.m gunzip.m \
   gzip.m inputname.m ismac.m ispc.m isunix.m license.m list_primes.m ls.m \
   ls_command.m menu.m mex.m mexext.m mkoctfile.m movefile.m \
-  news.m orderfields.m pack.m paren.m parseparams.m \
+  namelengthmax.m news.m orderfields.m pack.m paren.m parseparams.m \
   run.m semicolon.m setfield.m single.m substruct.m swapbytes.m tar.m \
   tempdir.m tempname.m texas_lotto.m unix.m unpack.m untar.m \
   unzip.m ver.m version.m warning_ids.m what.m xor.m zip.m
diff --git a/scripts/miscellaneous/namelengthmax.m 
b/scripts/miscellaneous/namelengthmax.m
new file mode 100644
--- /dev/null
+++ b/scripts/miscellaneous/namelengthmax.m
@@ -0,0 +1,39 @@
+## Copyright (C) 2008  David Bateman
+##
+## This file is part of Octave.
+##
+## Octave is free software; you can redistribute it and/or modify it
+## under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or (at
+## your option) any later version.
+##
+## Octave is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+## General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} namelengthmax ()
+## Returns the matlab compatible maximum variable name length. Octave is
+## capable of storing strings up to 
+## @iftex
+## @tex
+## $2^{31} - 1$
+## @end tex
+## @end iftext
+## @ifnottex
+## @code{2 ^ 31 - 1}
+## @end ifnottex
+## in length. However for matlab compatibility all variable, function
+## and structure field names should be shorter than the length supplied by
+## @code{namelengthmax}. In particular variables stored to a matlab file
+## format will have their names truncated to this length.
+## @end deftypefn
+
+function n = namelengthmax ()
+  n = 63;
+endfunction