On Tue, Sep 29, 2015 at 3:49 AM, M.-A. Lemburg <mal@egenix.com> wrote:
On 28.09.2015 23:49, Guido van Rossum wrote:
But that's a different point (for the record I'm not a big fan of the ? either).
Me neither.
Same here.
The proposal simply doesn't have the right balance between usefulness and complexity added to the language (esp. for new Python programmers to learn in order to be able to read a Python program).
+1
In practice, you can very often write "x or y" instead of having to use "x if x is None else y", simply because you're not only interested in catching the x is None case, but also want to override an empty string or sequence value with a default. If you really need to specifically check for None, "x if x is None else y" is way more expressive than "x ?? y".
For default parameters with mutable types as values, I usually write:
def func(x=None): if x is None: x = [] ...
I do the same. It has the right amount of explicitness and makes the default-case branch more obvious (subjectively, of course) than the proposed alternative: def func(x=None): x = x ?? [] ...
IMO, that's better than any of the above, but perhaps that's just because I don't believe in the "write everything in a single line" pattern as something we should strive for in Python.
Yeah, the language has been pretty successful at striking the right balance here. IMO, the proposed syntax doesn't pay off. -eric