Bug 1323247

Hello Dan,

Do you need any help adding Python 3 support to the RPM?

If you need more instructions, a [guide] for porting Python-based RPMs is available.

[guide] http://python-rpm-porting.readthedocs.org/en/latest/index.html

This bug appears to have been reported against 'rawhide' during the Fedora 25 development cycle.
Changing version to '25'.

Adding a Python 3 subpackage is not easy. The lcm build does not use setuptools, it builds with automake using AM_PATH_PYTHON which doesn't have any support for side-by-side Python 2 and Python 3 builds, it just builds for whatever is the first Python version it finds.

From my reading it seems there is a way to specify the Python version:

$ export PYTHON_VERSION=$(python -c "import sys; print(\"%s.%s\" % sys.version_info[:2])")

https://lcm-proj.github.io/build_instructions.html

Here's what I've seen packages do in similar cases:

- In build, copy the source to a separate directory, and do an extra build there passing python3 to configure. Then do the same in install. See [pyglet] for a very simple example. There might be ways to avoid building everything once.

- Create a new package just for the py3 bindings.

- Work with upstream to support side-by-side py2/py3 builds.

- Drop Python 2.


As always, let us know if you need help. If you'd like to invite others to solve this, you can set thit bug to block [PY3PATCH-REQUESTED].


[pyglet] http://pkgs.fedoraproject.org/cgit/rpms/python-pyglet.git/tree/python-pyglet.spec#n109
[PY3PATCH-REQUESTED] https://bugzilla.redhat.com/show_bug.cgi?id=1333765

A patch would be very welcome, I don't actually use lcm or have any experience with it, I've kind of ended up maintaining it by default because... reasons.

I guess the simplest (but most wasteful) option is just redo the whole build a second time with Python 3 enabled and then grab the modules out of that at the end.

I'll try to make a patch for that.

Created attachment 1193755 [details]
Patch that adds Python 3 support

Here's the patch!

%changelog:
- Added support for Python 3 — new subpackage lcm-python3
- The package is now being built two times, once with Python 2 bindings and
  the second time with Python 3 bindigs
- Renamed subpackage lcm-python to lcm-python2, added provides and obsoletes
  for the name lcm-python

What do you think?

Thanks Tomas.

I guess if we are renaming the -python subpackage we might as well switch the name around to the preferred naming style (python2-lcm / python3-lcm) right?

Also we can probably use the %{python_provide} macro to handle the Provides/Obsoletes.

Created attachment 1193932 [details]
Patch that adds Python 3 support

Oh, you're absolutely right, I thought there was a naming exception for bindings, I was mistaken.

Here's the updated version!

However, the explicit Provides and Obsoletes have to stay to provide the old name lcm-python.

Koji scratch build: http://koji.fedoraproject.org/koji/taskinfo?taskID=15373678

Thanks Tomas! Yes you are right, we need to explicitly Provide/Obsolete the lcm-python name.

Built in rawhide: http://koji.fedoraproject.org/koji/buildinfo?buildID=794528

I won't push this to stable releases, unless somebody particularly wants it.