On Wed, Sep 15, 2021 at 12:02:04PM -0700, Guido van Rossum wrote:
> To make chdir() return a context manager *and* keep it working without
> calling `__enter__`, it would have to call `getcwd()`, which I've heard is
> expensive.
>
> So I don't think that would work, alas.
How expensive would it have to be to rule it out?
Calling os.getcwd() is about 80% as costly as chdir on my machine so it
is clearly not free.
[steve ~]$ python3.9 -m timeit -s "import os" "os.getcwd()"
500000 loops, best of 5: 687 nsec per loop
[steve ~]$ python3.9 -m timeit -s "import os" "os.chdir('.')"
500000 loops, best of 5: 842 nsec per loop
But I don't think that chdir is likely to be the bottleneck in many
scripts.
--
Steve
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