Movatterモバイル変換
[0]ホーム
[Python-Dev] BDFL-Delegate appointments for several PEPs
Terry Reedytjreedy at udel.edu
Mon Mar 25 03:52:45 EDT 2019
On 3/25/2019 12:27 AM, Cameron Simpson wrote:> On 24Mar2019 23:22, Terry Reedy <tjreedy at udel.edu> wrote:>> On 3/24/2019 10:01 PM, Terry Reedy wrote:>>> On 3/24/2019 7:00 PM, Cameron Simpson wrote:>>>> Did you have a specific scenario in mind?>>>>>> I was thinking about IDLE and its tangled web of circular inports,>>> but I am now convinced that this change will not affect it. Indeed,>>> idlelib/pyshell.py already implements idea of the proposal, ending with>>>>>> if __name__ == "__main__":>>> sys.modules['pyshell'] = sys.modules['__main__']>>> main()>>>> After more investigation, I realized that to stop having duplicate>> modulue:>> 1. The alias should be 'idlelib.pyshell', not 'pyshell', at least when>> imports are all absolute.>> The PEP499 patch effectively uses __main__.__spec__.name for the name of> the alias. Does that simplify your issue?>> The current PR is here if you want to look at it:>> https://github.com/python/cpython/pull/12490The new test passes on Win10.>> 2. It should be done at the top of the file, before the import of>> modules that import pyshell.>> Hmm, if PEP499 comes in you shouldn't need to do this at all. If PEP499> gets delayed or rejected I guess you're supporting this without it. Yes,> you'll want to do it before any other imports happen (well, as you say,> before any which import pyshell).>> What about (untested):>> if __name__ == '__main__':> if __spec__.name not in sys.modules:When I start pyshell in my master repository directory on windows with python -m idlelib.pyshell__spec__.name is 'idlelib.pyshell, which I currently hard-coded.When I start with what should be equivalent python f:/dev/3x/lib/idlelib/pyshell.py__spec__ is None and __spec__.name an attribute error.> sys.modules[__spec__.name] = sys.modules['__main__']>> as a forward compatible setup?>>> If I run python f:/dev/3x/lib/idlelib/pyshell.py, the PEP patch would>> have to notice that pyshell is a module within idlelib and alias>> '__main__' to 'idlelib.pyshell', not 'pyshell'. Would the same be>> true if within-package import were all relative?>> I think so because we're using .__spec__.name, which I though was post> import name resolution.You must be doing something different when __spec__ is None ;-). I tested the patch and it does not raise AttributeError with the command above.> Testing in my PEP499 branch:>> Test 1:>> [~/src/cpython-cs at github(git:PEP499-cs)]fleet*> ./python.exe -i> Lib/idlelib/pyshell.py> Traceback (most recent call last):> File "<string>", line 1, in <module>> ModuleNotFoundError: No module named 'run'This is because of an obsolete 'command = ...' around 420. The if line is correct always and the if/then not needed.> >>> sys.modules['__main__']> <module '__main__' (<_frozen_importlib_external.SourceFileLoader> object at 0x1088e6040>)>> >>> sys.modules['pyshell']> <module '__main__' (<_frozen_importlib_external.SourceFileLoader> object at 0x1088e6040>)>> >>> sys.modules['idlelib.pyshell']> <module 'idlelib.pyshell' from> '/Users/cameron/src/cpython-cs at github/Lib/idlelib/pyshell.py'>>> So pyshell and idlelib.pyshell are distinct here.I verified that the module was being executed twice by putting print('running') at the top. __main__ and pyshell> are the same module, courtesy of your sys.modules assignment at the> bottom of pyshell.py.Obsolete and removed. Test 3 below will be with that commented out.>> Test 2:>> [~/src/cpython-cs at github(git:PEP499-cs)]fleet*> PYTHONPATH=$PWD/Lib> ./python.exe -i -m idlelib.pyshell> Traceback (most recent call last):> File "<string>", line 1, in <module>> ModuleNotFoundError: No module named 'run'> >>> sys.modules['__main__']> <module 'idlelib.pyshell' from> '/Users/cameron/src/cpython-cs at github/Lib/idlelib/pyshell.py'>> >>> sys.modules['pyshell']> <module 'idlelib.pyshell' from> '/Users/cameron/src/cpython-cs at github/Lib/idlelib/pyshell.py'>> >>> sys.modules['idlelib.pyshell']> <module 'idlelib.pyshell' from> '/Users/cameron/src/cpython-cs at github/Lib/idlelib/pyshell.py'>> >>> id(sys.modules['__main__'])> 4551072712> >>> id(sys.modules['pyshell'])> 4551072712> >>> id(sys.modules['idlelib.pyshell'])> 4551072712>> So this has __main__ and idlelib.pyshell the same module from the PEP499> patch and pyshell also the same from your sys.modules assignment.>> Test 3, with the pyshell.py sys.modules assignment commented out:>> [~/src/cpython-cs at github(git:PEP499-cs)]fleet*> PYTHONPATH=$PWD/Lib> ./python.exe -i -m idlelib.pyshell> Traceback (most recent call last):> File "<string>", line 1, in <module>> ModuleNotFoundError: No module named 'run'> >>> sys.modules['__main__']> <module 'idlelib.pyshell' from> '/Users/cameron/src/cpython-cs at github/Lib/idlelib/pyshell.py'>> >>> sys.modules['pyshell']> Traceback (most recent call last):> File "<stdin>", line 1, in <module>> KeyError: 'pyshell'> >>> sys.modules['idlelib.pyshell']> <module 'idlelib.pyshell' from> '/Users/cameron/src/cpython-cs at github/Lib/idlelib/pyshell.py'>> >>> id(sys.modules['__main__'])> 4552379336> >>> id(sys.modules['idlelib.pyshell'])> 4552379336>> Here we've got __main__ and idlelib.pyshell the same module and no> 'pyshell' in sys.modules.> I don't think I understand your "relative import" scenario.If files other that pyshell used relative 'import ./pyshell' instead of absolute 'import idlelib.pyshell', would the sys.modules key still be 'idlelib.pyshell' or 'pyshell'? Which is to ask, would the alias needed to avoid a second pyshell module still be 'idlelib.pyshell' or 'pyshell'?
More information about the Python-Devmailing list
[8]ページ先頭