From owner-bug-octave at bevo dot che dot wisc dot edu  Fri Dec 13 02:43:56 1996
Subject: assignment expression
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Andreas Weingessel <weingessel at ci dot tuwien dot ac dot at>
Cc: bug-octave at bevo dot che dot wisc dot edu
Date: Fri, 13 Dec 1996 02:41:32 -0600

On 12-Dec-1996, Andreas Weingessel <weingessel at ci dot tuwien dot ac dot at> wrote:

: The following assignment works fine:
: 
: octave:1> a(1,:)=rand(1,5)
: a =
: 
:   0.061189  0.593056  0.671360  0.300912  0.531030
: 
: The following assignment is obviously wrong, and octave responds with
: the right error message:
: 
: octave:2>  b(1,:)=rand(5,1)
: error: A(I, J) = X: X must be a scalar or the number of elements in I must
: error: match the number of rows in X and the number of elements in J must
: error: match the number of columns in X
: error: evaluating assignment expression near line 2, column 8
: 
: If you now want to correct the previous assignment, this assignment
: suddenly does not work, although it is the same as in the first line:
: 
: octave:3> b(1,:)=rand(1,5)
: error: A(I, J) = X: X must be a scalar or the number of elements in I must
: error: match the number of rows in X and the number of elements in J must
: error: match the number of columns in X
: error: evaluating assignment expression near line 3, column 7
: 
: 
: Although the variable b has not been defined yet (there has always
: been an error in the above expressions), it has a value
: 
: octave:4> b
: b =
: 
:   0  0  0  0  0
: 
: The variable also gets a value after the first (wrong) assignment
: 
: octave:5> c(1,:)=rand(5,1)
: error: A(I, J) = X: X must be a scalar or the number of elements in I must
: error: match the number of rows in X and the number of elements in J must
: error: match the number of columns in X
: error: evaluating assignment expression near line 5, column 7
: octave:6> c
: c = 0

Please try the following patch.

Thanks,

jwe


Fri Dec 13 02:01:32 1996  John W. Eaton  <jwe at bevo dot che dot wisc dot edu>

	* Array2-idx.h (assign): Delay resizing left hand side until we
	know if the assignment conforms.

	* ov.cc (octave_value::convert_and_assign): Preserve lhs value if
	assignment fails.


Index: Array2-idx.h
===================================================================
RCS file: /home/jwe/src/master/octave/liboctave/Array2-idx.h,v
retrieving revision 1.8
diff -c -r1.8 Array2-idx.h
*** Array2-idx.h	1996/12/09 18:05:38	1.8
--- Array2-idx.h	1996/12/13 08:01:24
***************
*** 334,339 ****
--- 334,355 ----
      }
  }
  
+ #define MAYBE_RESIZE_LHS \
+   do \
+     { \
+       if (liboctave_rre_flag) \
+ 	{ \
+ 	  int max_row_idx = idx_i_is_colon ? rhs_nr : idx_i.max () + 1; \
+ 	  int max_col_idx = idx_j_is_colon ? rhs_nc : idx_j.max () + 1; \
+  \
+ 	  int new_nr = max_row_idx > lhs_nr ? max_row_idx : lhs_nr; \
+ 	  int new_nc = max_col_idx > lhs_nc ? max_col_idx : lhs_nc; \
+  \
+ 	  lhs.resize (new_nr, new_nc, 0.0); \
+ 	} \
+     } \
+   while (0)
+ 
  template <class LT, class RT>
  int
  assign (Array2<LT>& lhs, const Array2<RT>& rhs)
***************
*** 378,396 ****
  	    }
  	  else
  	    {
- 	      if (liboctave_rre_flag)
- 		{
- 		  int max_row_idx = idx_i_is_colon ? rhs_nr : idx_i.max () + 1;
- 		  int max_col_idx = idx_j_is_colon ? rhs_nc : idx_j.max () + 1;
- 
- 		  int new_nr = max_row_idx > lhs_nr ? max_row_idx : lhs_nr;
- 		  int new_nc = max_col_idx > lhs_nc ? max_col_idx : lhs_nc;
- 
- 		  lhs.resize (new_nr, new_nc, 0.0);
- 		}
- 
  	      if (rhs_nr == 1 && rhs_nc == 1 && n > 0 && m > 0)
  		{
  		  RT scalar = rhs.elem (0, 0);
  
  		  for (int j = 0; j < m; j++)
--- 394,403 ----
  	    }
  	  else
  	    {
  	      if (rhs_nr == 1 && rhs_nc == 1 && n > 0 && m > 0)
  		{
+ 		  MAYBE_RESIZE_LHS;
+ 
  		  RT scalar = rhs.elem (0, 0);
  
  		  for (int j = 0; j < m; j++)
***************
*** 405,410 ****
--- 412,419 ----
  		}
  	      else if (n == rhs_nr && m == rhs_nc)
  		{
+ 		  MAYBE_RESIZE_LHS;
+ 
  		  for (int j = 0; j < m; j++)
  		    {
  		      int jj = idx_j.elem (j);
Index: ov.cc
===================================================================
RCS file: /home/jwe/src/master/octave/src/ov.cc,v
retrieving revision 1.10
diff -c -r1.10 ov.cc
*** ov.cc	1996/11/07 16:46:11	1.10
--- ov.cc	1996/12/13 08:34:36
***************
*** 590,607 ****
  
  	  if (tmp)
  	    {
! 	      if (tmp != rep)
  		{
  		  if (--rep->count == 0)
  		    delete rep;
  
! 		  rep = tmp;
! 		  rep->count = 1;
  		}
- 	      else
- 		delete tmp;
  
! 	      assignment_ok = try_assignment (idx, rhs);
  	    }
  	  else
  	    gripe_conversion_failed (type_name (), rhs.type_name ());
--- 590,612 ----
  
  	  if (tmp)
  	    {
! 	      octave_value *old_rep = rep;
! 	      rep = tmp;
! 	      rep->count = 1;
! 
! 	      assignment_ok = try_assignment (idx, rhs);
! 
! 	      if (! assignment_ok && old_rep)
  		{
  		  if (--rep->count == 0)
  		    delete rep;
  
! 		  rep = old_rep;
! 		  old_rep = 0;
  		}
  
! 	      if (old_rep && --old_rep->count == 0)
! 		delete old_rep;
  	    }
  	  else
  	    gripe_conversion_failed (type_name (), rhs.type_name ());