[Python-ideas] Fwd: Boolean behavior of None

[Oleg Broytman]

On Thu, Jan 17, 2013 at 03:10:45PM +0200, Ilkka Pelkonen <ilkka.pelkonen at iki.fi> wrote:
> It's not that it can't be done, just that it does something you don't
> expect. I've been professionally working with C++ for nine years in
> large-scale Windows systems, and I do expect a boolean expression return a
> boolean value.

   It does something Python developers expect. It's a well-known
behaviour and there are many programs that rely on that behaviour.

> Or, can you show me an example how the developer would benefit of the
> current behavior? Any operator traditionally considered as boolean will do.

address = user and user.address
if address is None:
    raise ValueError("Unknown address")

   In the example neither user nor user.address are allowed to be None.

Oleg.
-- 
     Oleg Broytman            http://phdru.name/            phd at phdru.name
           Programmers don't die, they just GOSUB without RETURN.