python 2 and 3 modules

[Baptiste Daroussin]

On Mon, Jul 29, 2013 at 12:26:24PM +0200, Marcus von Appen wrote:
> David Demelier <demelier.david at gmail.com>:
> 
> > 2013/7/29 Marcus von Appen <mva at freebsd.org>:
> >> David Demelier <demelier.david at gmail.com>:
> >>
> >>
> >>> 2013/7/28 Daniel Braniss <danny at cs.huji.ac.il>:
> >>>>
> >>>> Hi,
> >>>> I need to be able to have both (2.7 and 3.2) modules.
> >>>> setting PYTHON_VERSION=3.2 in /etc/make.conf compiles properly,
> >>>> but make install, insists that that the 2.7 version is installed!
> >>>> after deinstalling, it will install the 3.2 version in the correct
> >>>> directory:
> >>>>         /usr/local/lib/python3.2/site-path
> >>>> but now I lost the 2.7 version.
> >>>>
> >>>> the same happens if I try to install the 2.7 version, it will complain
> >>>> that the 3,2 version is installed.
> >>>>
> >>>> BTW, the comments in ports/Mk/bsd.python.mk are very confusing and
> >>>> some are wrong:
> >>>> # PYTHON_VERSION        - Version of the python binary in your ${PATH},
> >>>> in the
> >>>> #                                         format "python2.0". Set this in
> >>>> your
> >>>> makefile in case you
> >>>> #                                         want to build extensions with
> >>>> an
> >>>> older binary.
> >>>> #                                         default: depends on the version
> >>>> of
> >>>> your python binary
> >>>>
> >>>> setting it to "python3.2" produces errors in the make, while 3.2 is ok
> >>>>
> >>>> is there any fix?
> >>>>
> >>>> thanks,
> >>>>         danny
> >>>>
> >>>
> >>> For the moment its pretty difficult to install python 2.7 and 3.3 at
> >>> the same time. However, if you plan to install python 3.3, you need to
> >>> set PYTHON_DEFAULT_VERSION to "python3.3" and not PYTHON_VERSION.
> >>
> >>
> >> No, it is not.
> >>
> >> cd /usr/ports/lang/python27 && make install clean
> >> cd /usr/ports/lang/python32 && make install clean
> >> cd /usr/ports/lang/python33 && make install clean
> >>
> >> works like a charm. If you however want to use Python modules, it might
> >> become
> >> more difficult. It was discussed some time ago on the freebsd-python mailing
> >> list
> >> without an applicable result.
> >>
> >> If you need to have the same Python module for different versions around, I
> >> would
> >> recommend to use virtualenv in favour of the ports infrastructure, since
> >>
> >> make -DPYTHON_DEFAULT_VERSION=xxx <python-module>    - or -
> >> make -DPYTHON_VERSION=xxx <python-module>     - or -
> >> make -DPYTHON3_DEFAULT_VERSION=xxx <python-module>
> >>
> >> might mess up previous installations for a different python version.
> >>
> >> Cheers
> >> Marcus
> >>
> >
> > Of course from ports it will work. I've told about binary packages.
> >
> > When you bulk build a package for python 2.7 and python 3.3 the
> > /usr/local/bin/python will be included in both versions. Because bulk
> > building python 3 modules will requires to set PYTHON_DEFAULT_VERSION
> > and PYTHON3_DEFAULT_VERSION to the python 3.3 interpreter.
> >
> > Then the poudriere bulk will generate python 2.7 and python 3.3
> > pkg-plist including for both /usr/local/bin/python and all of the
> > non-versioned files I've already told above.
> >
> > You may now think "who cares? it build from ports". I would say no,
> > binary packages will be used more and more in the future.
> 
> I would not, either. This however is a problem with the package builder
> and ports infrastructure, which would need some install hooks to allow
> a check at installation time.
> 
That is totally wrong, that is a python bug (python is not the only one in that
case).

The ports have only be design for source installation, problem is when you are
buidling packages properly each packages are being done in a cleanroom aka a
jail without anything installed in it that makes python 3.3 port think it is
becoming the default because no other python are installed at that time.

This result in all python port defining bin/python, and thus they _do_ conflict
with each other. While this was/is silent with pkg_install, pkgng yell about it.
 
A fun thing you can do with pkg_install (in binary mode only no compilation from
sources and with packages built in a cleanroom)
# pkg_add -r python27
default is now python27
# pkg_add -r python33
default is now python33
# pkg_delete python27
hey I have no default python anymore.

Java is solving the problem by using a javawrapper. There is 3 possible way to
solve the situation with python, move the symlink dancing into a post install
script. Have a javawrapper like thing.

I would love to see a generic alternative/eselect/javawrapper-like thing appear
that can handle all of this what ever the kind of port is.

To be back to the subject this is really a ports problem, because noone was
until now really using the binary only packages, and the one doing it have never
analyzed what they really do once installed.

regards,
Bapt
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