Re: gEDA-dev: New diagram (attempt at UML)

[Steve Meier <smeier-at-NOSPAMalchemyresearch_dot_com>]

I think I like the union inside the object especially for complex
objects which has a list of 

GList *prim_objs;    // Other Primitive objects 

else it would have to have lists for arcs, boxes, circles, lines, text
and pictures.



struct st_complex {

  char *basename;

  BOOL is_hierarchy_io;    // is this an interpage hierarchical symbol?
  BOOL is_schematic_sym;   // is this a symbol that has a schematic?

  DISPLAY *display;   // how object relates to world and display window

  BOOL embeded;

  GList *net_pin_objs;         // list of net pins

  GList *bus_pin_objs;         // list of bus pins

  GList *hidden_nets;          // list of nets

  GList *prim_objs;            // Other Primitive objects 
};




On Thu, 2007-03-22 at 10:01 +0000, Peter Clifton wrote:
> On Wed, 2007-03-21 at 20:20 -0800, Steve Meier wrote:
> > This is a non-object oriented version, c straight no ice.
> > 
> > struct st_object {
> >   char obj_type;  // defined in o_types.h
> > 
> >   int reference_count;
> > 
> >   union {
> >     ARC           *arc;
> >     BOX           *box;
> >     BUSRIPPER     *busripper;
> >     CIRCLE        *circle;
> >     COMPLEX       *complex;
> >     CONN          *connector;
> >     GEDA_VERSION  *version;
> >     LINE          *line;
> >     PLACEHOLDER   *placeholder;
> >     PICTURE       *picture;
> >     PIN           *pin;
> >     SEGMENT       *segment;
> >     TEXT          *text;
> >   } data;
> > 
> > 
> >   BOOL selected;            // object selected flag
> >   BOOL visible;
> >   BOOL locked;
> >  
> >   BOOL hierarchy_is_disabled;
> > 
> >   // attributes from symbol files
> >   GList *sym_attribs;
> > 
> >   // attributes from schematic files
> >   GList *sch_attribs;
> > };
> 
> I'd probably not embed the objects as a union - although I'm not sure.
> It is certainly better than the current way which has one of every
> structure just in case.
> 
> I'd imagine going the gobject way, and start the "subclass" structure
> with the parent's structure. C guarantees that this first element is
> first in the struct's allocated memory, so you can type-cast say an ARC
> object into the generic object. (OBJECT*)my_arc->object_property.
> 
> gobject also does some other things, like maintaining fields in the
> gobject structure which it can verify your casting at run-time, and has
> similarly inherited class structures for methods (it is fully object
> oriented).
> 
> gobject isn't favoured for libgeda, but this way of inheriting
> structures could be used (carefully).
> 
> Regards,
> 



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