On Tue, 10 Dec 2019 at 00:00, Steven D'Aprano <st...@pearwood.info> wrote:
>
> On Sat, Dec 07, 2019 at 07:37:58PM +0000, Oscar Benjamin wrote:
>
> > I recently hit on a situation that created a one million line code file:
> > https://github.com/pytest-dev/pytest/issues/4406#issuecomment-439629715
> >
> > The original file (which is included in SymPy) has 3000 lines
> > averaging 500 characters per line so that the total file is 1.5MB.
> > Since it is a test file pytest rewrites the corresponding pyc file and
> > adds extra lines to annotate the intermediate results in the large
> > expressions. The pytest-rewritten code has just over a million lines.
>
> If I'm reading you correctly, you're saying that, on average, pytest
> annotates each line of source code with over 300 additional lines of
> code.
To be clear that's what happens with this particular file but is not
otherwise typical of pytest. The idea is to rewrite something like
assert f(x+y) == z
as
tmp1 = x+y
tmp2 = f(tmp1)
tmp3 = z
it tmp1 != tmp2:
# Print information showing the intermediate expressions tmp1,
tmp2, tmp3
This rewriting is normally useful and harmless but it explodes when
used with complicated mathematical expressions like this:
https://github.com/sympy/sympy/blob/d670689ae212c4f0ad4549eda17a111404694a27/sympy/solvers/tests/test_ode.py#L295
--
Oscar
_______________________________________________
Python-Dev mailing list -- python-dev@python.org
To unsubscribe send an email to python-dev-le...@python.org
https://mail.python.org/mailman3/lists/python-dev.python.org/
Message archived at
https://mail.python.org/archives/list/python-dev@python.org/message/S74ZEASIWBXXEEMOO4KBFBZ4NFGYSKZD/
Code of Conduct: http://python.org/psf/codeofconduct/
