[Python-ideas] PEP 505: None-aware operators

[Giampaolo Rodola']

On Mon, Jul 23, 2018 at 11:52 AM Steve Dower <steve.dower at python.org> wrote:

> I'm borderline on ?[] right now. Honestly, I think it works best if it
> also silently handles LookupError (e.g. for traversing a loaded JSON
> dict), but then it's inconsistent with ?. which I think works best if it
> handles None but allows AttributeError.

That would easily make typos pass unnoticed:

    request.context.user.usernme  # raises AttributeError
    request?.context?.user?.usernme  # return None

Same goes for LookupError: if a key or index is missing on 'a?[b]' I
do want an exception. If I don't, which should be the exception rather
than the rule, I will simply take the risk myself and do:

    default = '<no name>'
    try:
        name = d['user']['details']['name'] or default
    except KeyError:
        name = default

But certainly there should be no native syntax encouraging me to do
any of that. Talking about arbitrarily swallowing exceptions is the
worst direction this proposal can take as it breaks yet another
fundamental Python Zen: "errors should never pass silently". IMO this
shows how fundamentally detached from the base philosophy of the
language this whole idea is.

--
Giampaolo - http://grodola.blogspot.com