[Python-Dev] Adding a conditional expression in Py3.0

[BJörn Lindqvist]

> > I think I'd prefer (if <expr> then <expr> else <expre>) i.e. no
> > colons.
>
> My problem with this syntax is that it can be hard to read:
>
> return if self.arg is None then default else self.arg
>
> looks worryingly like
>
> return NAME NAME.NAME NAME NAME NAME NAME NAME NAME.NAME

That can already be written in Python:

return self.arg or default

And maybe the syntax of the future conditional operator could be
extended so that:

return self.arg else default

Would be equivalent to the previous line. For stuff were a conditional
expression really is needed, like in:

return if self.arg then "yes" else "no"

One would hope that whoever writes the conditional expression doesn't
make the expressions so long and complicated that it looks like NAME
NAME.NAME NAME... It doesn't matter which syntax proposal that wins,
it will still be very tempting to write unreadable code with it (think
nested/chained conditional expressions). That (and the fact that I've
never felt a real need for a conditional expression thanks to the "or"
operator) is my very humble argument against it.

--
mvh Björn