I'm using 64bit Arch Linux and Python 2.7.2 compiled with GCC 4.6.1.

I have noticed in several ocassions that the interpreter is complaining about

AttributeError: XMLGenerator instance has no attribute '_write' (in case of module xml.sax.saxutils.XMLGenerator)

or

AttributeError: RendererGDK instance has no attribute '_text2path' (in case of matplotlib when trying to use TeX formatting of text)

When I have a look into the corresponding modules I can clearly see method definitions (e.g. def _write(self, text) in line 97 of xml/sax/saxutils.py

I have no clue, why it is happening in some modules, but not in others. If a write my own module containing a class with a _write method it is working fine.
If I write a class derived from xml.sax.saxutils.XMLGenerator and overwrite the _write method it is known to the system, but many of the attributes beginning with an underscore appear still to be unknown...

This is very odd?!

I'd like to mention that Python 2.6.7 does not show this erroneous behavior. In Python 2.6.7 I can call the _write method of xml.sax.saxutils.XMLGenerator...

Is this a bug or a feature in 2.7??

The problem appeared to be the package from the Arch Linux repo.
Compiling the source codes myselfes gave me a Python interpreter not showing this bug...