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Re: Restrictions



Am Tue, 06 Jan 2004 08:35:29 +0100 hat Michael Sperber <sperber@xxxxxxxxxxxxxxxxxxxxxxxxxxx> geschrieben:

"Felix" == Felix Winkelmann <felix@xxxxxxxxxxxxx> writes:

Felix> Michael Sperber wrote:

felix> Note that the Chicken FFI (for example) does not allow GC during the
felix> invocation of foreign code,

Sure, and that *greatly* simplifies a lot of issues.  It's also an
unacceptable restriction for many Scheme systems.

Felix> Well, I wonder what that should be. Could you provide an example?

Any environment where

- C code allocates
- allocation may trigger a GC to provide the requested space

Huh? Then perform a callback. Where's the problem?

(BTW, if you re-read the message you're quoting, it says:

"Note that the Chicken FFI (for example) does not allow GC during the invocation of foreign code,
 unless callbacks are explicitly used"
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)


These include, at the very least:

- Scheme 48
- scsh
- MzScheme
- Gambit-C
- Elk

(In case you completely misunderstood: Chicken allows callbacks.
Callbacks may allocate, allocation may GC, i.e. C code called in Chicken
may GC)


PS: Please note this is SRFI 50; you posted to the SRFI 40 mailing
    list


Yep, sorry. I noticed two seconds too late and reposted it.


cheers,
felix