Re: So, what the heck is a continuation anyway?

[Dan Sugalski <address@hidden>]

At 03:36 PM 12/10/2001 -0600, Paul Prescod wrote:
>Dan Sugalski wrote:
> >
> >...
> >
> > Perl's stack is pretty much independent of the C/system stack, so that's
> > not a problem. We have other problems to compensate, of course. :)
>
>I wonder if that is always true. ;)

"It's not a problem, it's a learning experience" ;-)

>Consider: Perl code calls into Expat or Tk.
>Expat or Tk of course uses the C stack.
>Expat or Tk calls back into Perl.
>
>Now, how do you build a continuation that takes into account the *C
>stack* being used by Expat or Tk?

You don't. Or, rather, I don't. You've unfortunately put forth a rather 
tricky problem--"How do you make a complex piece of software do very tricky 
and underhanded things without that software's consent?" I don't think it's 
entirely possible, so we punt and do the best we can. (And if you think 
it's fun with Tk, try it with Oracle. You can probably imagine the pain 
from there) It's the same sort of issues as you get with threads. Some 
libraries may just not be continuation safe the way some aren't thread-safe.

This would probably be the place to do some gale-force handwaving in the 
"worse is better" paper direction. ;-P

					Dan

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Dan Sugalski                          even samurai
dan@sidhe.org                         have teddy bears and even
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