Comparison with False - something I don't understand

[Tim Harig]

On 2010-12-03, Paul Rubin <no.email at nospam.invalid> wrote:
> Steven D'Aprano <steve+comp.lang.python at pearwood.info> writes:
>>> There are better ways to handle errors than Python's exception system.
>> I'm curious -- what ways would they be?
>> I'm aware of three general exception handling techniques: ...
>> What else is there?
>
> The Erlang approach is to chop the application into a lot of very
> lightweight processes, and let any process that encounters an error
> simply crash.  A monitoring process notices the crashed process and
> restarts it.  There is a "supervision tree" of uber-monitor processes
> that restart crashed monitor proceses.  I haven't programmed in that
> style myself and I'm not persuaded that it's better than what Python
> does, but I think it's different from the stuff on your list, which is

Erlang also offers an exception syntax almost identical to Python's for use
within a single process.

What makes Erlang's supervisor mode of error handling superior is that it
works for more then just the current vm.  If a process throws an exception,
the supervisor catches and handles it.  If a vm dies, a supervisor from
another vm takes over.  If an entire computer dies, a supervisor on another
computer takes over.  OTP provides some extremely advanced support for
supervisory structures.

> an answer to your "what else is there".  I do know that they write some
> complex, very high reliability systems (phone switches) in Erlang.

Erlang isn't what I would call a very general purpose programming language
like Python; but, if you want to build highly scalable and/or highly
available systemes, there really isn't anything else that comes close
to it.  I am not really a huge fan of the purely functional nature of
the language; but, light weight processes using the actor model is the
way to go for concurrent processing.

The BEAM virtual machine is also a powerful system with its ability to
patch systems on the fly.  It has start to become the target for other
languages.  I know of two that are in current developement.  I wouldn't
mind seeing a version of Python that could leverage the power of the
BEAM vm.