Re: [Sbcl-devel] with-timeout sucks

[Christophe R. <cs...@ca...>]

Attila Lendvai <att...@gm...> writes:

> i just had a thought on WITH-DEADLINE while guarding a piece of code
> against any SERIOUS-CONDITION:
>
> (handler-case
>     (something-short-that-may-fail-but-its-ok)
>   (serious-condition ()
>     (log-a-warning-and-move-on)))
>
> this seems to be a reasonable piece of code, but if it's used in a
> context where there is a deadline installed, and if that deadline is
> signalled from inside of it, then it'll muffle the deadline.
>
> is this code bad style?

I would say "yes": handling all SERIOUS-CONDITIONs indiscriminately (and
moving on) is likely to be a bad thing.  The SERIOUS-CONDITIONs that are
not ERRORs are things that are conceptually the computer going wrong:
running out of heap or stack space, detecting memory corruption
errors -- the kinds of thing that probably warrant something more than
being caught by a generic handler-case.

ERRORs, by contrast, are conventionally things going wrong with the
program or its execution.  I don't know whether deadlines are
conceptually ERRORs or SERIOUS-CONDITIONs, but even if they're
implemented that way it doesn't make it OK to handle all the other kinds
of ways in which the computer can go wrong.

Cheers,

Christophe