[Wheel-builders] [Matplotlib-devel] Manylinux external library test case - matplotlib, tk

[Matthew Brett]

Hi,

On Tue, May 3, 2016 at 4:47 PM, Matthew Brett <matthew.brett at gmail.com> wrote:
> On Tue, May 3, 2016 at 5:35 AM, Olivier Grisel <olivier.grisel at ensta.org> wrote:
>>> I tested it with:
>>>
>>> import matplotlib
>>> matplotlib.use('PyQt5')
>>
>> Typo, this was supposed to read:
>>
>> matplotlib.use('Qt5Agg')
>
> Meanwhile, I tried removing (patchelf --remove-needed) the
> requirements of _tkagg.so on the vendored libtk, libtcl, and added
> back the requirement (patch --add-needed) on general `libtk.so' and
> 'libtcl.so'.  This removed the segfault and allowed me to display
> `plt.range(10)'.  I suppose then, that the tk / tcl ABI that we are
> using is relatively stable across versions 8.4 (on the docker image)
> and 8.6 (on Debian sid).
>
> Worth experimenting with this - or too much of a hack?

I have experimented with this.  It does seem that we can get away with
using the system tcl / tk libraries as installed, at least on a couple
of Debian systems I have.

Now there's a new problem, to do with linux library namespaces.  We
need the _tkagg.so file to use the same libraries as the Python
Tkinter package at run time.    There can be more than one tcl / tk
version installed on a given system, so, as things stand, we'd need to
inspect the Tkinter extension modules to see what they are using, and
then work out a way to use those libraries at run time.  Here are the
questions for the experts out there:

* Can anyone think of a way of using the symbol namespace of the
tkinter extension modules directly, to pick up the symbols we need
rather than re-importing the libraries?
* If we do discover which libraries Tkinter is using, what would be a
good way of pulling in these libraries at run-time?

Cheers,

Matthew