On Thu, Jan 4, 2018 at 4:56 PM, Greg Ewing <greg.ew...@canterbury.ac.nz> wrote:
> Guido van Rossum wrote: > >> It was get_context() in an earlier version of PEP 567. We changed it to >> copy_context() believing that that would clarify that you get a clone that >> is unaffected by subsequent ContextVar.set() operations (which affect the >> *current* context rather than the copy you just got). >> > > In that case it seems clear to me that "the context" is > conceptually a mutable mapping. The fact that it happens > to be built out of immutable components is an implementation > detail that user-level docs should not be talking about. > Well, it's not *immutable* (it shouldn't support hash()), but it doesn't follow the MutableMapping protocol -- it only follows the Mapping protocol. Note that the latter carefully doesn't call itself ImmutableMapping. Context is a mutable object that implements the Mapping protocol. The only way to mutate a Context is to use var.set() when that Context is the current context. (Modulo the caching bug discussed in the subthread with Nathaniel.) -- --Guido van Rossum (python.org/~guido)
_______________________________________________ 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/archive%40mail-archive.com
