[Python-ideas] Boolean behavior of None

[Antoine Pitrou]

Le Thu, 17 Jan 2013 15:10:45 +0200,
Ilkka Pelkonen <ilkka.pelkonen at iki.fi> a écrit :
> Hi Oleg, others,
> 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.

"and" is not a boolean operator, it is a shortcutting control flow
operator.
Basically, what you are looking for is:

    flag = element.is_visible() if element else False

(or, more explicitly:
    flag = element.is_visible() if element is not None else False
)

Regards

Antoine.