[pypy-dev] Pypy bugs

[Armin Rigo]

Hi Elefterios,

On Sun, May 8, 2011 at 12:18 PM, Elefterios Stamatogiannakis
<estama at gmail.com> wrote:
> You are exactly right, and i've more or less used code like the one you
> presented. My only problem is that i believe that pypy shouldn't have
> answered at my first example (In [12]:...) above that cElementTree
> exists in xml.etree .Or maybe it should short circuit cElementTree to
> point at ElementTree. To declare that something exists, and then when
> somebody tries to use it, to throw an exception, isn't that nice.

Nothing we can do: the module cElementTree is actually written in
Python also in CPython --- it is cElementTree.py --- but it import
internally "_elementtree".  So there is no way PyPy can know that
cElementTree cannot be imported before actually trying to.

The workaround to write "try: import cXxx; except ImportError: import
xxx" is the general solution.  It works in other cases too (cProfile,
cPickle, cStringIO, etc).  And also, it works in case the version of
CPython you are running on misses some C extension modules.  For
example you would get the exact same error as you got on PyPy if you
are running on a CPython where the C module "_elementree" was not
compiled.


A bientôt,

Armin.