[matplotlib-devel] Error when matplotlib.use'ing 'Cairo'

[Kynn J. <ky...@gm...>]

On my system, the following 3-line script

*import matplotlib
matplotlib.use('Cairo')
import matplotlib.pyplot as plt
*
fails with the error:

*  File "<path-to-mpl-egg>/matplotlib/backends/backend_cairo.py", line 34,
in <module>
   if cairo.version_info < _version_required:
AttributeError: 'module' object has no attribute 'version_info'
*
It's easy to see that the bug is in matplotlib.backends.backend_cairo;
here's the part of the code that produces the error:

*try:
  import cairo
except ImportError:
  raise ImportError("Cairo backend requires that pycairo is installed.")

_version_required = (1,2,0)
if cairo.version_info < _version_required:
  raise ImportError ("Pycairo %d.%d.%d is installed\n"
                    "Pycairo %d.%d.%d or later is required"
                    % (cairo.version_info + _version_required))
*
Indeed, the cairo module has no version_info attribute:

*% python
Python 2.6.1 (r261:67515, Feb 11 2010, 00:51:29)
[GCC 4.2.1 (Apple Inc. build 5646)] on darwin
>>> import cairo
>>> cairo.version_info
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'version_info'
*
(FWIW, the version of pycairo I have installed is 1.8.10 .)

So matplotlib.backends.backend_cairo needs some other way to determine the
version number for the cairo module, but I don't understand this module
sufficiently well to provide a patch for this bug.

~kj