Re: guile-gobject/g-wrap status update

[Andreas Rottmann <a dot rottmann at gmx dot at>]

Rob Browning <rlb@defaultvalue.org> writes:

> Andreas Rottmann <a.rottmann@gmx.at> writes:
>
>> [BTW: There seem to be two guile-gtk mailing lists ATM - I guess
>> people should migrate to the one at GNU...]
>>
>> I'm ATM working at implementing "glueless" wrapping for g-wrap,
>> i.e. instead of using a dedicated C wrapper for each wrapped function
>> creating an applicable smob that invokes a general marshaller which in
>> turn calls the C function via libffi.
>
> Interesting.  A couple of questions come to mind.  First, how portable
> is libffi?  Will it cover all the existing architectures?
>
At auric.debian.org:

rotty@auric:~% madison libffi2
   libffi2 |  1:3.0.4-7 |        stable | alpha, arm, i386, ia64, m68k, powerpc, s390, sparc
   libffi2 | 1:3.3.2-0pre4 |       testing | alpha, arm, i386, ia64, m68k, powerpc, s390, sparc
   libffi2 | 1:3.3.2-0pre4 |      unstable | arm, m68k, powerpc, s390, sparc
   libffi2 | 1:3.3.2-0pre5 |      unstable | alpha, i386, ia64

So libffi seems pretty portable.

> Also, do we know what the overhead's likely to be?  I suppose the
> performance argument could go either way when comparing to the
> existing approach since the existing one-function-per-wrapper
> approach may well have poorer interactions with the memory
> hierarchy.  In any case, I do want to preserve the ability for
> people who want to, to be able to have close to minimal ffcall
> overhead using g-wrap.
>
I plan to make "glueless" wrapping an optional feature that you can
turn on and off at your delight (at wrapper creation time, that is, of
course).

> When calling from interpreted languages, you may have a lot more
> leeway before you noticably affect performance, but in the long run,
> I'm hoping guile will also provide some form of compilation.
>
Yes, I'd like to see that, too.

> On a related front, I've decided to just use CVS at savannah, so I
> should be setting that up over the next week (plus or minus -- I
> have family coming to visit).
>
Cool. I think that you can integrate GNU arch somehow with CVS, so if
we are going to do multi-branch development (which CVS is poor at), we
could have just the mainline in CVS and use arch for the harrier stuff
I think.  I've not yet very much looked into arch, but perhaps someone
else here has real experience.

> It also probably makes sense to have a place where those interested
> can discuss "what should happen next" with g-wrap.  I'm happy to
> have that discussion on an existing list if that would be
> appropriate, or to create a new one.  I've had some ideas I'd like
> to discuss, and to compare and contrast (to the extent that they
> overlap) with the above.
>
Maybe guile-gtk is appropriate (the GNU one, /methinks), but I'm not
the one to decide this and I'll be happy either way.

Regards, Andy
-- 
Andreas Rottmann         | Rotty@ICQ      | 118634484@ICQ | a.rottmann@gmx.at
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