[Python-Dev] Remove typing from the stdlib

[Eric V. Smith]

On 11/3/2017 12:15 PM, Victor Stinner wrote:
> Hi,
> 
> 2017-11-03 15:36 GMT+01:00 Guido van Rossum <guido at python.org>:
>> Maybe we should remove typing from the stdlib?
>> https://github.com/python/typing/issues/495

> The typing module is not used yet in the stdlib, so there is no
> technically reason to keep typing part of the stdlib. IMHO it's
> perfectly fine to keep typing and annotations out of the stdlib, since
> the venv & pip tooling is now rock solid ;-)

I'm planning on using it for PEP 557:
https://www.python.org/dev/peps/pep-0557/#class-variables

The way the code currently checks for this should still work if typing 
is not in the stdlib, although of course it's assuming that the name 
"typing" really is the "official" typing library.

         # If typing has not been imported, then it's impossible for
         #  any annotation to be a ClassVar. So, only look for ClassVar
         #  if typing has been imported.
         typing = sys.modules.get('typing')
         if typing is not None:
             # This test uses a typing internal class, but it's the best
             #  way to test if this is a ClassVar.
             if type(a_type) is typing._ClassVar:
                 # This field is a ClassVar. Ignore it.
                 continue

See also https://github.com/ericvsmith/dataclasses/issues/14

Eric.