Keep MISSING. On Dec 28, 2017 8:44 AM, "Yury Selivanov" <yselivanov...@gmail.com> wrote:
> On Thu, Dec 28, 2017 at 4:51 AM, Victor Stinner > <victor.stin...@gmail.com> wrote: > > Hi, > > > > I like the new version of the PEP using "read only mapping" and > > copy_context(). It's easier to understand. > > Thanks, Victor! > > > > > I'm ok with seeing a context as a mapping, but I am confused about a > context > > variable considered as a mapping item. I still see a context variable as > a > > variable, so something which has a value or not. I just propose to rename > > the default parameter of the ContextVar constructor. > > As Nathaniel already explained, a 'default' for ContextVars is > literally a default -- default value returned when a ContextVar hasn't > been assigned a value in a context. So my opinion on this is that > 'default' is the less ambiguous name here. > > [..] > > > > * a read-only attribute ``Token.old_value`` set to the value the > > variable had before the ``set()`` call, or to ``Token.MISSING`` > > if the variable wasn't set before. > > > > > > Hum, I also suggest to rename Token.MISSING to Token.NOT_SET. It would be > > more conistent with the last sentence. > > I like MISSING more than NOT_SET, but this is very subjective, of > course. If Guido wants to rename it I rename it. > > > > C API > > ----- > > > > > > Would it be possible to make this API private? > > We want _decimal and numpy to use the new API, and they will call > ContextVar.get() on basically all operations, so it needs to be as > fast as possible. asyncio/uvloop also want the fastest copy_context() > and Context.run() possible, as they use them for *every* callback. So > I think it's OK for us to add new C APIs here. > > > > > > 2. ``int PyContextVar_Get(PyContextVar *, PyObject *default_value, > > PyObject **value)``: > > (...) ``value`` is always a borrowed > > reference. > > > > > > I'm not sure that it's a good idea to add a new public C function which > > returns a borrowed reference. I would prefer to only use (regular) strong > > references in the public API. > > Sure, I'll change it. > > Yury > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: https://mail.python.org/mailman/options/python-dev/ > guido%40python.org >
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