[pypy-dev] Pypy bugs

[Dan Stromberg]

Hi Elefterios.

I don't really work on PyPy, but I've written code that runs on PyPy and
CPython 2&3 and Jython, unmodified.  I tried IronPython too, but it was too
different from the others.

On Sat, May 7, 2011 at 6:13 PM, Elefterios Stamatogiannakis <
estama at gmail.com> wrote:

> Hi all, and many many thanks for pypy. Your work on pypy is exceptional.
>
> Due to Roger Binns doing the first steps of porting APSW on top of pypy,
> i've tried my project (madIS: http://code.google.com/p/madis ) with pypy
> and head APSW, and found the following:
>
> In python 2.7.1:
> In [1]: print dict.__setattr__
> <slot wrapper '__setattr__' of 'object' objects>
>
> In pypy 1.5:
> In [10]: print dict.__setattr__
> <unbound method dict.__setattr__>
>
> In essence in python 2.7.1 dict.__setattr__ is the same as
> object.__setattr__ whereas in pypy dict.__setattr__ works only with
> dictionaries, so it throws the following error when called with an object:
>
> TypeError: unbound method __setattr__() must be called with dict
> instance as first argument
>
> Above problem was solved by changing all dict.__setattr__ invocations
> into object.__setattr__ invocations, and now the same code works in both
> CPython and pypy.
>

Actually, this feels a bit like it was a portability issue in your code to
me.  Why should dict's __setattr__ apply to all objects?  Doesn't it seem
more natural that it would apply to dicts alone, and if it applies to more,
that that's an implementation detail?


> The second problem that i found with pypy is this:
>
> In [12]: import xml.etree.c
> xml.etree.cElementTree
>
> Above is to show that cElementTree exists in pypy's xml.etree. If then i
> try to import cElementTree:
>
> In [11]: import xml.etree.cElementTree
> ---------------------------------------------------------------------------
> ImportError                               Traceback (most recent call last)
>
> /home/estama/programs/pypy-15/bin/<ipython console> in <module>()
>
> /home/estama/programs/pypy-15/lib-python/2.7/xml/etree/cElementTree.pyc
> in <module>()
>       1 # Wrapper module for _elementtree
>
>       2
> ----> 3 from _elementtree import *
>
> ImportError: No module named _elementtree
>
> Thanks again for pypy, and to Roger Binns for your outstanding work on
> APSW.
>

PyPy in general doesn't include a bunch of C extension modules; it's written
in Python and RPython, so this seems somewhat natural.  Your code probably
should do something like:

try:
   import xml.etree.cElementTree as element_tree
except ImportError:
   import xml.etree.ElementTree as element_tree

...and then use element_tree.whatever in your code.  It's 3 more lines, but
more  portable.

HTH.
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