realtime design

[Peter Hansen]

Will Stuyvesant wrote:
> I think this can be done.  I need a function, lets call it
> rcall(...), that accepts a *maximumtime* parameter, a value
> representing milliseconds, and that calls a function *f* in
> the existing software.  If *f* returns before maximumtime
> passes everything is just like when calling the *f* function
> without rcall.  Else rcall returns 'timeout' at about time ==
> *maximumtime*.  I can think of many other useful functions for
> realtime software, but something like rcall(...) is the first
> I would like to have.

This sounds like a pretty simple thing to do, using a thread
to call the function, but that doesn't mean the resulting
system will in any way be considered "realtime" unless you
have a fairly simplistic definition.  You can't get around
the underlying fact that Python itself has aspects that are
not deterministic, nor that unless you are running on top of
a realtime operating system, no application can be considered
realtime, by the usual definitions.  More info required...

-Peter