On Sat, Aug 08, 2009 at 14:43 +1000, Gordon Wrigley wrote: > Since I have no clear concept of what is supposed to happen when a C > function called via ctypes does a printf, I have instead gone through > the C library and arranged to have all the printing routed through a > function pointer which I now setup as a python callback that does a > sys.stdout.write(). Problem solved.
if you can try to ensure open the file (look for "fdopen(2)" or so) in unbuffered mode that should work. Would be good to know. I have played on the command line and it appeared to me that this buffering mode is very likely the culprit. cheers, holger > On Fri, Aug 7, 2009 at 8:31 PM, Gordon Wrigley<py-...@tolomea.com> wrote: > > I need to have a think about what you've said and look at producing a > > minimal reproduction. However I did forget to mention that the prints > > from the python code are fine, it's only the ones from C that are > > affected, in the good case the two sets are interleaved in the py.test > > capture, in the bad case the python prints are in the py.test capture > > and the C prints come out of py.test's stdout. > > Now that I think about it some more I'm inclined to wonder from where > > (and when) the C library acquires it's stdout handle. > > > > On Fri, Aug 7, 2009 at 8:02 PM, holger krekel<hol...@merlinux.eu> wrote: > >> Hi Gordon, > >> > >> On Fri, Aug 07, 2009 at 18:53 +1000, Gordon Wrigley wrote: > >>> My python code talks to a C library via ctypes and it in turn prints > >>> debug to stdout. > >>> And we test this with py.test, which by itself works just fine. > >> > >> by this you mean that it looks roughly like this: > >> > >> http://paste.pocoo.org/show/132982/ > >> > >> right? > >> > >>> But if at the bash prompt we then redirect the output of py.test to a > >>> file suddenly the C debug starts propagating out of py.test. > >> > >> hum, redirecting the above example with "py.test x.py >log" works fine. > >> > >> The following may be interesting to observe (i just did): > >> > >> def test_hello(): > >> myfile = os.fdopen(1, "w") > >> myfile.write("hello\n") > >> myfile.flush() > >> assert 0 > >> > >> This works fine but if i leave out the flush() the write > >> will *not* be captured appropriately. I guess that it is because > >> of the missing buffering ("os.fdopen(1, 'w', 1)" and no flush works) > >> > >> FYI the pytest_capture plugin resumes capturing for calling > >> into test methods, setup/teardown code and collection > >> respectively and otherwise suspends capturing. Even if this > >> was modified (i.e. capturing would always happen) i imagine > >> that the missing flush/close could associate the actual write > >> into a different test. > >> > >> Maybe your behaviour is still a different issue or even a bug, though. > >> > >>> We generally run py.test with -v and -x, but removing those didn't > >>> change the behavior at all. > >> > >> that shouldn't change anything related to capturing, indeed. > >> > >>> I'm at a bit of loss as to where to begin with this one, any suggestions? > >> > >> maybe my above considerations help a bit and you can maybe > >> come up with a breaking example or fix things on your side? > >> > >> I want to do a 1.0.1 soon with some capturing fixes (related > >> to unicode handling, though) and i'd like to include any other > >> related improvements or add to the docs. > >> > >> best, > >> holger > >> > >>> gord...@gohma:~$ uname -a > >>> Linux gohma 2.6.28-14-generic #47-Ubuntu SMP Sat Jul 25 00:28:35 UTC > >>> 2009 i686 GNU/Linux > >>> gord...@gohma:~$ python > >>> Python 2.6.2 (release26-maint, Apr 19 2009, 01:56:41) > >>> [GCC 4.3.3] on linux2 > >>> Type "help", "copyright", "credits" or "license" for more information. > >>> >>> import py > >>> >>> py.version > >>> '1.0.0' > >>> > >>> Regards, > >>> Gordon > >>> _______________________________________________ > >>> py-dev mailing list > >>> py-dev@codespeak.net > >>> http://codespeak.net/mailman/listinfo/py-dev > >>> > >> > >> -- > >> Metaprogramming, Python, Testing: http://tetamap.wordpress.com > >> Python, PyPy, pytest contracting: http://merlinux.eu > >> > > > -- Metaprogramming, Python, Testing: http://tetamap.wordpress.com Python, PyPy, pytest contracting: http://merlinux.eu _______________________________________________ py-dev mailing list py-dev@codespeak.net http://codespeak.net/mailman/listinfo/py-dev
