[Octave-bug-tracker] [bug #37961] textscan : whitespace specification doesn't work

[Philip Nienhuis]

Update of bug #37961 (project octave):

                  Status:         Patch Submitted => Invalid                
             Open/Closed:                    Open => Closed                 

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Follow-up Comment #11:

Your analysis is spot-on:

>> ver
------------------------------------------------------------------------------------------------
MATLAB Version: 8.1.0.47 (R2013a)
:
<snip>

>> A = textscan ('XQPCTick;Tag', '%s;%s')
A = 
    {1x1 cell}    {0x1 cell}
>> A{:}
ans = 
    'XQPCTick;Tag'
ans = 
   Empty cell array: 0-by-1


while Octave with 3.7.0+ textscan/strread gives:

octave.exe:1> A = textscan ('XQPCTick;Tag', '%s;%s')
warning: implicit conversion from scalar to sq_string
warning: Ambiguous '☺' specifier next to literal in column
A =
{
  [1,1] =
  {
    [1,1] = XQPCTick;Tag
  }
  [1,2] = {}(0x1)
}


There is something fishy in Octave but I cannot easily see where the first
warning comes from. I've fixed the second warning to be more clear
(http://hg.savannah.gnu.org/hgweb/octave/rev/4294430ef736).
Anyway the comments (that I added long time ago) in strread.m around L.600 do
confirm your analysis: when using a "%s" format you can't expect Octave, or
ML, to reliably distinguish the corresponding text field from an immediately
following literal.

That, plus different results in r2012b than in r2013a for your second call is
adequate to close this bug with "Invalid".

BTW your patch does give some useful hints on how to process repeated
whitespace in %s fields. If I get time & need it myself, and jwe doesn't beat
me with textcan.cc, I might have another look at it.

Let's leave it to Jordi to decide if he wants a more robust
strread/textscan/textread for upcoming 3.6.4.

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