From octave-sources-request at bevo dot che dot wisc dot edu  Tue Feb 13 23:26:38 2001
Subject: cell array patch
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Paul Kienzle <pkienzle at kienzle dot powernet dot co dot uk>,         octave-sources@bevo.che.wisc.edu
Date: Tue, 13 Feb 2001 23:26:34 -0600

On 13-Feb-2001, I wrote:

| On  5-Nov-2000, Paul Kienzle <pkienzle at kienzle dot powernet dot co dot uk> wrote:
| 
| | While implementing assignment, I noticed that =[] is an operator in
| | Matlab.  That is, "x(i)=[];" deletes the ith element of x, but "y=[];
| | x(i)=y;" gives a non-conformant arguments error.  Putting deletion in
| | the parse.y and separating assignment from deletion would make the code
| | in liboctave somewhat cleaner, and fix a hack that I needed to implement
| | cell array deletion.
| 
| I decided to see how difficult this might be.  It *seems* that it should
| be relatively easy, but I believe that it is not, unless you are
| willing to give up the idea that an assignment should produce a
| value.  In other words, you would not be able to write
| 
|   x = y = z = [];

I may have spoken too soon.  Giving up assignment as a value (even in
the case of assignment of []) may not be required, and it may not be
terribly difficult (by recognizing an empty matrix, and tagging the
expression as such, then handling it as a special case when the parser
builds the assignment tree).

Sorry to clutter this list with non-source nonsense.

jwe



-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
-------------------------------------------------------------