doc: Properly find the version

[jehane]

The conf.py can't import nibabel if nibabel isn't installed, as is the
case when installing nibabel for the first time.

[bochecha]

In case you wonder why @jehane sent a pull-request for my commit, that's because I wrote the patch to help them and then completely forgot to open this pull-request. 😄

[coveralls]

Coverage remained the same at 95.947% when pulling cef68ac on jehane:master into ec4567f on nipy:master.

[codecov-io]

Current coverage is 93.97% (diff: 100%)

Merging #488 into master will not change coverage

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Powered by Codecov. Last update ec4567f...cef68ac

[effigies]

Looks reasonable.

👍 for merge.

[matthew-brett]

The change is reasonable, but I believe the docs will not build correctly without an installation of nibabel. What do you get if you try and build the docs when nibabel is not installed?

[bochecha]

Seems to work just fine with this patch applied.

In a virtualenv, I did:

$ pip install -r doc-requirements.txt
...
$ make htmldoc
...
Build finished. The HTML pages are in ../build/html.
make[1]: Leaving directory '/home/mathieu/Workspace/nibabel/doc'

Then if I open $(pwd)/build/html/index.html in Firefox I get what looks like your documentation, with the user manual, API doc, etc.

[matthew-brett]

I think in that case that import nibabel will also work because you are running from the nibabel root directory. But, if I do:

cd doc
make html

I get lots of errors like this in the doc build

/Users/mb312/dev_trees/nibabel/doc/source/neuro_radio_conventions.rst:83: WARNING: Exception occurred in plotting neuro_radio_conventions-2
 from /Users/mb312/dev_trees/nibabel/doc/source/neuro_radio_conventions.rst:
Traceback (most recent call last):
  File "/Users/mb312/.virtualenvs/test/lib/python2.7/site-packages/matplotlib/sphinxext/plot_directive.py", line 517, in run_code
    six.exec_(code, ns)
  File "/Users/mb312/.virtualenvs/test/lib/python2.7/site-packages/matplotlib/externals/six.py", line 672, in exec_
    exec("""exec _code_ in _globs_, _locs_""")
  File "<string>", line 1, in <module>
  File "<string>", line 1, in <module>
ImportError: No module named nibabel

and the API part of the documentation lists the submodules, but the content is empty.

[matthew-brett]

@bochecha - any comments here? For example, I wonder whether we just need a better error message if nibabel is not installed.

[bochecha]

I think in that case that import nibabel will also work because you are running from the nibabel root directory. But, if I do:

cd doc
make html

I think this is the root of the problem.

Indeed, make htmldoc works just fine without nibabel installed, and without this patch, since it sets PYTHONPATH correctly.

I think when we had the problem originally with @jehane was because we had cd doc && make html.

So maybe make htmldoc needs to be emphasized as the right way to build the docs.

For example, I wonder whether we just need a better error message if nibabel is not installed.

Perhaps that error message could just tell people to run make htmldoc from the root dir?

[matthew-brett]

Thanks for analyzing the problem a bit more. How about #503 ?