This is the mail archive of the guile@cygnus.com mailing list for the guile project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]

Re: Critical sections and marking of free cells

Mikael Djurfeldt <mdj@nada.kth.se> writes:

<snip>

> *and* switch the order between the SETCAR and SETCDR, writing, instead
> of the above:
> 
> SCM_NEWCELL (z);
> SCM_SETCDR (z, <malloced memory>);
> SCM_SETCAR (z, scm_tc16_<name>);

If this is acceptable, I'd also suggest introducing a new, higher-level
abstraction for initializing a SMOB instance.  In Scwm, we have:

#define SCWM_NEWCELL_SMOB(ANSWER,ID,PSMOB) \
   do { \
     SCM_NEWCELL((ANSWER)); \
     SCM_SETCDR((ANSWER),(SCM) (PSMOB)); \
     SCM_SETCAR((ANSWER),(ID)); \
   } while (0)

The pattern occurs frequently enough that it's definitely worth
abstracting -- if this had already been done, the change you suggest
would just be a change to the macro definition, and not to lots of lines 
of code.  When making the change is the perfect time to raise the level
of abstraction so that future changes will be less painful.

Greg