[m-users.] MR_GC_free ?

[Volker Wysk]

Hi

Am Mittwoch, dem 08.11.2023 um 05:53 +1100 schrieb Zoltan Somogyi:
> On 2023-11-08 05:48 +11:00 AEDT, "Volker Wysk" <post at volker-wysk.de> wrote:
> > Hi.
> > 
> > In the ODBC library, there's space allocated by MR_GC_NEW and explicitly
> > freed with MR_GC_free. This confuses me. Shouldn't space allocated by
> > MR_CG_NEW be deallocated by the garbage collector? If it is to be
> > deallocated explicitly, shouldn't the space be allocated by MR_NEW and be
> > deallocated by MR_free?
> 
> Follow the definition of MR_GC_free in runtime/mercury_memory.h
> to boehm_gc/include/gc.h.

This leads to this (I couldn't understand the definition of this function):

/* Explicitly deallocate an object.  Dangerous if used incorrectly.     */
/* Requires a pointer to the base of an object.                         */
/* An object should not be enabled for finalization (and it should not  */
/* contain registered disappearing links of any kind) when it is        */
/* explicitly deallocated.                                              */
/* GC_free(0) is a no-op, as required by ANSI C for free.               */
GC_API void GC_CALL GC_free(void *);

So the gc explicitly frees the object and remembers that it has done so, so
it won't be garbage collected later.

Is it bad style to use MR_GC_NEW and MR_GC_free, since it should rather be
done with MR_NEW/MR_free? (That's what those are there for, aren't they?)

Volker