[Patches] GC patch 3 and 4

[Vladimir Marangozov]

Neil Schemenauer wrote:
> 
> On Thu, Jun 29, 2000 at 05:20:35AM +0200, Vladimir Marangozov wrote:
> > Neil Schemenauer wrote:
> > > The major problem I see with the current API is that PyObject_NEW
> > > and PyObject_DEL are not symmetric.  When GC is enabled
> > > PyObject_NEW returns an object pointer while PyObject_DEL takes a
> > > GC pointer.
> > 
> > I see. Would it make sense for PyObject_NEW to return the GC pointer ?
> > (only if the object type supports GC).
> 
> I would say that's a step in the wrong direction.  Since the
> PyObject_Init code has to access the object structure two
> conversions would have to be done.  Also, I don't like that part
> of the implementation leaking out.  If PyObject_DEL could be made
> a statement instead of an expression then something like:
> 
>     #ifdef WITH_CYCLE_GC 
>     #define PyObject_DEL(op) do { \
>             if (PyObject_IS_GC(op)) { \
>                 PyObject_FREE(PyObject_AS_GC(op)); \
>             } else { \
>                 PyObject_FREE(op); \
>             } \
>             } while (0);
>     #else
>     #define PyObject_DEL(op) PyObject_FREE(op)
>     #endif
> 
> would do the trick.  The PyObject_AS_GC garbage in types could
> then be dropped.  A quick look at the code indicates that
> PyObject_DEL as a statement would be okay for the types
> supporting GC.  Could this work?  Is it a good idea?

Yes. Go for it!

I wanted to avoid it but there's a price to pay and it seems that the
other way around is more expensive and indeed, not so clean.
OTOH, this is the genuine inlined version of PyObject_Del() which is good.

In objimpl.h, in the WITH_CYCLE_GC block, the above would look like

#ifdef WITH_CYCLE_GC
...
#undef PyObject_DEL
#define PyObject_DEL(op) ( PyObject_IS_GC(op) ? \
                           PyObject_FREE(PyObject_AS_GC(op)) : \
                           PyObject_FREE(op) )
...
#endif


-- 
       Vladimir MARANGOZOV          | Vladimir.Marangozov@inrialpes.fr
http://sirac.inrialpes.fr/~marangoz | tel:(+33-4)76615277 fax:76615252