matplotlib-devel Mailing List for matplotlib

On 10/23/10 10:35 PM, jas...@cr... wrote:
> On 10/22/10 7:16 PM, Michael Droettboom wrote:
>>     On 10/22/2010 05:45 PM, Russell E. Owen wrote:
>>> I'm curious when the next release of matplotlib is due.
>>>
>>> My application is suffering badly from the issue that an incorrect font
>>> cache will cause matplotlib to fail (the application mysteriously exits
>>> partway through startup until the user deletes the font cache).
>>>
>>> That problem is allegedly fixed on the trunk and I'm trying to decide
>>> how best to deal with it. Depending on the timing of 1.0.1 I can decide
>>> whether it's worth putting in my own workaround, bundling a prerelease
>>> version of matplotlib or just waiting for the official release.
>> I'm not sure what the timeframe is on 1.0.1.
>>
>> What problem with the cache are you referring to?  I'm aware of a
>> problem where if some fonts are moved or removed after the cache is
>> created matplotlib will crash (and this problem is fixed in the trunk),
>> but is that really a problem in everyday practice?  I'm just curious --
>> if there's another issue with the cache that I'm not aware of, I'd like
>> to fix it.
>> '
>
>
> We've been running into problems in Sage that seem to occur because font
> caches from 1.0.0 make old versions of matplotlib die.  I haven't seen
> the problem myself, but several Sage developers have put in quite a bit
> of time in diagnosing the problem.  In the end, I think they wrote a
> patch to do custom MPLCONFIGDIR for different versions of matplotlib in
> different versions of Sage.
>
> I'm CCing sage-devel, in case one of the sage devs that ran into
> problems wants to comment.
>

John Palmieri asked me to forward his response (below) about the 
problems Sage has been having with matplotlib and backward incompatibility:

Thanks,

Jason


==========================================================

The Sage developers have found two issues with MPLCONFIGDIR:

- First, when upgrading from version 0.99.3 to 1.0.0, the contents of
that directory seem to cause compatibility problems.  That is, once
you upgrade to a version of Sage using 1.0.0, it overwrites whatever
was in that directory, and then you get errors when using an older
version of Sage which still uses 0.99.3.  See
<http://trac.sagemath.org/sage_trac/ticket/9221#comment:82> for an
example of the sort of error which arises, and see
<http://trac.sagemath.org/sage_trac/ticket/6235> for our fix: in Sage,
we set MPLCONFIGDIR to different directories based on the version of
matplotlib.

- Second, the following code in matplotlib/texmanager.py can cause a
race condition when creating MPLCONFIGDIR:

   if not os.path.exists(DIR):
       os.mkdir(DIR)

In particular, when running doctests for Sage, if MPLCONFIGDIR doesn't
exist, two different doctests can try to create it at the same time,
causing a problem.  (I've also heard people suggest that these sort of
race conditions can be security issues, but I don't know about the
validity of this.)  See
<http://trac.sagemath.org/sage_trac/ticket/10159> for our fix: we
replace those lines by

   try:
       os.mkdir(DIR)
   except OSError, e:
       if e.errno == errno.EEXIST:
            pass
       else:
            raise

(and also add "import errno" at the beginning of the file).

I'd be happy to hear any comments you might have about these.

-- 
John Palmieri
jhp...@gm...

Hello,

recently I upgraded to matplotlib 1.0.0 which I mainly use for plotting in my (python 2.6 based) application with Qt4 GUI. Overall it works fine, but there are a few issues I experienced also with the previous version, especially with the toolbar.

When building a standalone version using py2exe, images of the toolbar are missing. I had to manually modify the .svg extensions
to .png in the _init_toolbar() function in backend_qt4.py. And for the new 'qt4_editor_options' option, no png existed yet.

Since I wanted to get rid of some toolbar functions in my standalone app, I wanted to create my own backend. But following the instructions in the backend_template.py didn't help me much. In the comments at the beginning of this file it says:

"...add 'xxx' to the switchyard in matplotlib/backends/__init__.py and 'xxx' to the backends list in the validate_backend methon in
matplotlib/__init__.py and you're off."

Unfortunately it doesn't work this way (anymore).

Is it possible to update the instructions on doing your own backend? Updating the Qt4 backend would help as well.
I know this is not the right place for feature requests, but anyway: it would be nice to have some flexibility in modifying the toolbar (which functions to add or not,etc). Now I do it the quick and dirty way: I comment out the toolbar items in the _init_toolbar() function in backend_qt4.py. However, depending on the app I'm working on, I have to comment/uncomment it...

Kind regards,

Jelmer

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