On 5/4/2012 11:58 PM, Glenn Linderman wrote:
On 5/4/2012 8:48 PM, Terry Reedy wrote:
CPython is developed, tested, packaged, distributed, and installed as
one unit. It is intended to be run as one package. If something caches
a copy of python.exe, it seems to me that it should check and update
as needed. Could venv check the file date of the current python.exe
versus that of the one cached, much like is done with .pyc compiled
code caches?
I almost wrote this response (using different words, but the same idea)
but concluded that:
1) Python wouldn't run far without its standard library, so a venv check
would have to be very early, and likely coded in C, and therefore
probably has to be part of Python.exe
2) If it was not part of Python.exe, it would have to work similarly to
the launcher, and there would be yet one more process sitting around
waiting for Python to exit (on Windows, where there is no exec).
So I concluded that probably Python.exe needs to make the check, but if
it is aware it existing in venv, it might be able to put out a better
message than "just" the mismatch between exe and lib; or at least the
message should mention the possibility of an old venv cache.
The gist of my response is that the venv 'tail' should way the python
'dog' as little as possbile.
I also wonder how often such incompatibility occurs. Optionally changing
the de facto semantics of CPython's built-in dict in bug-fix releases
was a rather unique event. I am sure we would all be happy to never have
to do such again.
--
Terry Jan Reedy
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