From bug-octave-request at bevo dot che dot wisc dot edu Tue Dec 17 18:34:14 2002
Subject: Variables not being cleared
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Andrew Jackson <andrew dot jackson at jesus dot ox dot ac dot uk>
Cc: bug-octave at bevo dot che dot wisc dot edu
Date: Tue, 17 Dec 2002 18:33:52 -0600

On 13-Dec-2002, Andrew Jackson <andrew dot jackson at jesus dot ox dot ac dot uk> wrote:

| I'm not certain this is a bug, but it is certainly different behaviour
| between 2.1.36 and 2.1.40.
| 
| I have two script files, one calling the other. The first sets up variables
| that I don't want to have to enter every time I call the second script. The
| second does an exist() on the variables to see if I need to enter them.
| 
| The problem arises that having run the scripts once despite calling clear
| and checking the existance of the variables manually with who and exist
| (they have gone) when I rerun the script the variables, which are all
| defined as globals magically reappear with their previous values.
| 
| Clear in 2.1.36 works and the variable *really* are cleared, whereas in
| 2.1.40 they only appear to have been cleared.
| 
| An example:
| ---Script A---
| global A B C
| A = 1;
| B = 2;
| scriptb
| ---End Script---
| 
| ---Script B---
| global A B C
| if (!exist('A'))
| 	A = input('A: ');
| endif
| if (!exist('B'))
| 	B = input('B: ');
| endif
| if (!exist('C'))
| 	C = input('C: ');
| endif
| A
| B
| C
| ---End Script---
| 
| The octave session :
| 
| octave:1> scripta
| C: 12
| A = 1
| B = 2
| C = 12
| octave:2> clear
| octave:3> who -variables
| octave:4> exist('A')
| ans = 0
| octave:5> exist('B')
| ans = 0
| octave:6> exist('C')
| ans = 0
| octave:7> scripta
| A = 1
| B = 2
| C = 12
| octave:8> 
| 
| Whereas 2.1.36 asks for C on the second run.

With 2.1.40, you need to use either

  clear global  %% Matlab compatible

or

  clear -global

to clear global variables.  Unfortunately, there is an off-by-one
error that prevents the "-global" option from working.  The patch
below should fix that problem.

Thanks,

jwe


2002-12-17  John W. Eaton  <jwe at bevo dot che dot wisc dot edu>

	* variables.cc (Fclear): Fix off-by-one error.


Index: src/variables.cc
===================================================================
RCS file: /usr/local/cvsroot/octave/src/variables.cc,v
retrieving revision 1.236
diff -u -r1.236 variables.cc
--- src/variables.cc	3 Dec 2002 19:48:57 -0000	1.236
+++ src/variables.cc	18 Dec 2002 00:32:49 -0000
 at @ -1700,7 +1700,7 @@
 		break;
 	    }
 
-	  if (idx < argc)
+	  if (idx <= argc)
 	    {
 	      if (! have_dash_option)
 		{



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