From octave-maintainers-request at bevo dot che dot wisc dot edu  Tue Mar  2 01:43:06 1999
Subject: A global variable, "x", in traditional mode gives exist("x") == 1 even  in a function where x is not defined.
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Mats Jansson <mats dot jansson at networks dot nera dot no>
Cc: octave-maintainers at bevo dot che dot wisc dot edu
Date: Tue, 2 Mar 1999 01:41:31 -0600 (CST)

On 25-Feb-1999, Mats Jansson <mats dot jansson at networks dot nera dot no> wrote:

| Bug report for Octave 2.0.13.90 configured for i386-redhat-linux-gnu
| 
| Description:
| -----------
| In traditional mode (initialize_global_variables = 1):
| If a global variable is defined (eg. "x"), exist("x") returns 1 even in
| a function where x is not defined.
| 
| 
| Repeat-By:
| ---------
| 
| [mj at localhost demo]$ octave --traditional
| Octave, version 2.0.13.90 (i386-redhat-linux-gnu).
| Copyright (C) 1996, 1997, 1998 John W. Eaton.
| This is free software with ABSOLUTELY NO WARRANTY.
| For details, type `warranty'.
| 
| >> type problem
| problem is the function defined from: /home/mj/fest/demo/problem.m
| 
| function problem(x)
|   exist("x")
|   if exist("x") == 1, disp(x), endif
| endfunction
| >> problem
| ans = 0
| >> global x
| >> problem
| ans = 1
| error: `x' undefined near line 3 column 28
| error: evaluating expression near line 3, column 28
| error: evaluating argument list element number 1
| error: evaluating index expression near line 3, column 23
| error: evaluating if command near line 3, column 3
| error: called from `problem' in file `/home/mj/fest/demo/problem.m'
| >> clear                       
| >> initialize_global_variables = 0
| initialize_global_variables = 0
| >> problem
| ans = 0
| >> global x
| >> problem
| ans = 0
| >> exit
| [mj at localhost demo]$ 

Please try the following patch.  I hope it doesn't break anything
else.

Thanks,

jwe



Tue Mar  2 01:36:29 1999  John W. Eaton  <jwe at bevo dot che dot wisc dot edu>

	* variables.cc (Fexist): If a variable isn't defined, only go on
	to look for a global by the same name if we are at the top level.

*** src/variables.cc~	Tue Jun 23 15:49:46 1998
--- src/variables.cc	Tue Mar  2 01:35:54 1999
***************
*** 354,360 ****
      }
  
    symbol_record *sr = curr_sym_tab->lookup (symbol_name, 0, 0);
!   if (! (sr && sr->is_defined ()))
      sr = global_sym_tab->lookup (symbol_name, 0, 0);
  
    retval = 0.0;
--- 354,361 ----
      }
  
    symbol_record *sr = curr_sym_tab->lookup (symbol_name, 0, 0);
!   if (! (sr && (sr->is_defined ()
! 		|| (curr_sym_tab != top_level_sym_tab))))
      sr = global_sym_tab->lookup (symbol_name, 0, 0);
  
    retval = 0.0;