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

[Leonardo Rochael Almeida]

On 11 May 2016 at 10:58, Matthew Brett <matthew.brett at gmail.com> wrote:

> On Tue, May 10, 2016 at 6:38 PM, Nathaniel Smith <njs at pobox.com> wrote:
> > On Tue, May 10, 2016 at 3:09 PM, Leonardo Rochael Almeida
> > <leorochael at gmail.com> wrote:
> >> On 10 May 2016 at 18:52, Matthew Brett <matthew.brett at gmail.com> wrote:
> >>>
> >>> On Tue, May 10, 2016 at 5:26 PM, Matthew Brett <
> matthew.brett at gmail.com>
> >>> wrote:
> >>> >> [...]
> >>> >>
> >>> >> This would probably look like:
> >>> >>
> >>> >> _tkagg.so has a DT_NEEDED entry naming tkinter.so (or whatever
> Python
> >>> >> calls
> >>> >> this module)
> >>> >>
> >>> >> Before loading _tkagg.so, we use Python level introspection figure
> out
> >>> >> where
> >>> >> tkinter.so lives
> >>> >>
> >>> >> We add its directory to LD_LIBRARY_PATH
> >>> >>
> >>> >> we import _tkagg.so
> >>> >>
> >>> >> We take its directory back off of LD_LIBRARY_PATH
> >>> >>
> >>> >> Very weird, but I can't see why it wouldn't work, and probably more
> >>> >> reliable
> >>> >> than anything where we try to reimplement the dynamic loader's
> search
> >>> >> logic
> >>> >> ourselves.
> >>> >
> >>> > Nice - yes - it does work in a first-pass test - I'll look into
> >>> > automating that.
> >>>
> >>> Ah - except I do not believe it is possible to change the linker path
> >>> for Python modules, within the Python process:
> >>>
> >>> http://www.gossamer-threads.com/lists/python/python/393770#393770
> >
> > Doh :-(
>
> Any other suggestions?
>

Calling `patchelf` at runtime with the result of introspecting the
`_tkinter.so` module? :-)

On a more serious note, even though it would be dangerous to call
`sys.setdlopenflags()` with `RTLD_GLOBAL`, we could perhaps manually call:

   - ctypes.CDLL("/path/to/introspected/libtk.so", DLFCN.RTLD_GLOBAL)
   - ctypes.CDLL("/path/to/introspected/libtcl.so", DLFCN.RTLD_GLOBAL)

before importing a `_tkagg.so` with `libtk` and `libtcl` patchelf-removed
(but not re-added).

We would be dumping only libtcl/tk's symbols in the namespace of other
python extension modules.


> I guess this will be a problem for the external library PEP?
>

Likely, yes.
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