On 10:29 pm, gu...@python.org wrote:
On Sat, Feb 6, 2010 at 12:49 PM, Ezio Melotti <ezio.melo...@gmail.com>
wrote:
In #7712 I was trying to change regrtest to always run the tests in a
temporary CWD (e.g. /tmp/@test_1234_cwd/).
The patches attached to the issue add a context manager that changes
the
CWD, and it works fine when I run ./python -m test.regrtest from
trunk/.
However, when I try from trunk/Lib/ it fails with ImportErrors (note
that
the latest patch by Florent Xicluna already tries to workaround the
problem). The traceback points to "the_package = __import__(abstest,
globals(), locals(), [])" in runtest_inner (in regrtest.py), and a
"print
__import__('test').__file__" there returns 'test/__init__.pyc'.
This can be reproduced quite easily:
[snip]
I haven't tried to repro this particular example, but the reason is
that we don't want to have to call getpwd() on every import nor do we
want to have some kind of in-process variable to cache the current
directory. (getpwd() is relatively slow and can sometimes fail
outright, and trying to cache it has a certain risk of being wrong.)
Assuming you mean os.getcwd():
exar...@boson:~$ python -m timeit -s 'def f(): pass' 'f()'
10000000 loops, best of 3: 0.132 usec per loop
exar...@boson:~$ python -m timeit -s 'from os import getcwd' 'getcwd()'
1000000 loops, best of 3: 1.02 usec per loop
exar...@boson:~$
So it's about 7x more expensive than a no-op function call. I'd call
this pretty quick. Compared to everything else that happens during an
import, I'm not convinced this wouldn't be lost in the noise. I think
it's at least worth implementing and measuring.
Jean-Paul
_______________________________________________
Python-Dev mailing list
Python-Dev@python.org
http://mail.python.org/mailman/listinfo/python-dev
Unsubscribe:
http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
