Structure assignments

[John W. Eaton]

On 27-Aug-2007, David Bateman wrote:

| In looking at how Octave and Matlab handle comma separated lists as
| input and output arguments of functions, I noted that structure arrays
| can equally be used to create a comma separated list. So I then thought
| that something like
| 
| x = ceil (randn (10, 1));
| in = struct ('call1', {x, Inf, 'last'}, 'call2', {x, Inf, 'first'});
| out = struct ('call1', cell (2, 1), 'call2', cell (2, 1));
| [out.call1] = find (in.call1);
| [out.call2] = find (in.call2);
| 
| should be valid and in fact it is in Matlab R20007a. However, in Octave
| 2.9.13 a comma separated list created from a structure array is only
| valid as an input to a function, and not at all on the LHS... What would
| be involved in adding this feature? Should it be done before 3.0?

Try the following patch.  It should fix the problem you mention but not
the additional [x(idx).a] = ... case.

jwe


src/ChangeLog:

2007-08-27  John W. Eaton  <address@hidden>

        * Cell.h (Cell::Cell (const octave_value_list&)): Create row
        vector instead of column vector.

        * pt-idx.cc (tree_index_expression::lvalue): Handle [x.a] =
        ... style assignments.
        * ov-struct.cc (octave_struct::subsasgn): Handle case of RHS as
        comma-separated list.


Index: src/Cell.h
===================================================================
RCS file: /cvs/octave/src/Cell.h,v
retrieving revision 1.31
diff -u -u -r1.31 Cell.h
--- src/Cell.h  15 Nov 2006 16:12:58 -0000      1.31
+++ src/Cell.h  27 Aug 2007 17:09:50 -0000
@@ -45,7 +45,7 @@
     : ArrayN<octave_value> (dim_vector (1, 1), val) { }
 
   Cell (const octave_value_list& ovl)
-    : ArrayN<octave_value> (dim_vector (ovl.length (), 1))
+    : ArrayN<octave_value> (dim_vector (1, ovl.length ()))
     {
       for (octave_idx_type i = 0; i < ovl.length (); i++)
        elem (i) = ovl (i);
Index: src/ov-struct.cc
===================================================================
RCS file: /cvs/octave/src/ov-struct.cc,v
retrieving revision 1.84
diff -u -u -r1.84 ov-struct.cc
--- src/ov-struct.cc    10 Aug 2007 19:07:35 -0000      1.84
+++ src/ov-struct.cc    27 Aug 2007 17:09:54 -0000
@@ -363,7 +363,18 @@
 
            std::string key = key_idx(0).string_value ();
 
-           map.assign (key, t_rhs);
+           if (t_rhs.is_cs_list ())
+             {
+               Cell tmp_cell = Cell (t_rhs.list_value ());
+
+               // FIXME -- shouldn't care if the dimensions of the
+               // RHS don't match the dimensions of the subscriped
+               // LHS.
+
+               map.assign (key, tmp_cell);
+             }
+           else
+             map.assign (key, t_rhs);
 
            if (! error_state)
              {
Index: src/pt-idx.cc
===================================================================
RCS file: /cvs/octave/src/pt-idx.cc,v
retrieving revision 1.32
diff -u -u -r1.32 pt-idx.cc
--- src/pt-idx.cc       10 Aug 2007 19:07:35 -0000      1.32
+++ src/pt-idx.cc       27 Aug 2007 17:09:54 -0000
@@ -476,9 +476,22 @@
 
            case '.':
              {
-               idx.push_back (octave_value (get_struct_index (p_arg_nm, 
p_dyn_field)));
+               octave_value tidx = get_struct_index (p_arg_nm, p_dyn_field);
 
-               if (error_state)
+               if (! error_state)
+                 {
+                   idx.push_back (tidx);
+
+                   if (i == n-1)
+                     {
+                       // Last indexing element.  Will this result in a
+                       // comma-separated list?
+
+                       if (first_retval_object.is_map ())
+                         retval.numel (first_retval_object.numel ());
+                     }
+                 }
+               else
                  eval_error ();
              }
              break;