BTW, even for the "compare to None" issue, the situation in 0.1.1 isn't as bad as you might think. Definitely a "<NullCoalesce proxy for None>" cannot be compared as "is None". But even there, this works:
NullCoalesce(spam).bacon <NullCoalesce proxy for None> NullCoalesce(spam).bacon == None True NullCoalesce(spam).bacon == 0 False NullCoalesce(spam).bacon is None False
So yeah, the docs should say "If you are using the `coalescing` library, use `==` rather than `is` to compare values with None". Yes, that's contrary to best style in general Python... but it's a pretty small change to make in that specialized code that needs to deal with "hierarchical semi-structured data that uses None (rather than missing attributes or other sentinels) to mark unreachable branches." On Wed, Jul 25, 2018 at 11:53 PM David Mertz <david.mertz@gmail.com> wrote:
On Wed, Jul 25, 2018, 11:27 PM Chris Angelico <rosuav@gmail.com> wrote:
That's a bug in my proxy too. I'll figure out how to fix it in 0.1.2 soon. This is early alpha, and the things you're noting are valuable bug reports. But none of this is fundamentally unfixable in a library, nor even especially difficult.
If you're going to make that work, then by definition you would be wrapping up the None, right? Which would mean that every one of the prints would say "<NullCoalesce proxy for None>". Which, in turn, means that you cannot do this:
NullCoalesce(spam).nil is None
or rather, it will always be False. With PEP 505, you most certainly *can* do this check, because it would really truly be None.
This IS fundamentally unfixable in a library.
If your meaning of "fix" is simply "add new syntax", of course that's true. If it's "solve the actual problem that motivates the PEP" I can definitely fix it.
Right now, you can still always call .unbox() at the end to get the underlying value. I agree that's a little ugly, hence why I added the wrapt proxy stuff. Most operations trigger unboxing, but indeed not simply echoing to the shell.
I think I'll add a property spelled '_' to make it less busy (but more cryptic, I know). E.g.
NullCoalesce(spam).nil.nil.nil._ is None'
I also added an unbox() function that will pass through non-proxy objects untouched. So it's safe to unbox anything if you are unsure what it is.
Of course I'm not claiming any library is without a need to work with it's quirks and limits. But they are very few even in this 4-hours-of-work alpha.
-- Keeping medicines from the bloodstreams of the sick; food from the bellies of the hungry; books from the hands of the uneducated; technology from the underdeveloped; and putting advocates of freedom in prisons. Intellectual property is to the 21st century what the slave trade was to the 16th.