Multiple versions of Python packages (2.7 vs 3.4)

[Miroslav Lachman]

Shane Ambler wrote on 03/17/2016 01:08:
> On 16/03/2016 23:39, Miroslav Lachman wrote:
>> I checked that most files are installed in versioned subdirectory, for
>> example python2.7/site-packages, some tools have versioned binaries like
>> /usr/local/bin/pip-2.7 but they have also symlink /usr/local/bin/pip.
>> Are there any way to create / install those packages without creating
>> this symlink?
>> If I didn't miss something the symlinks are the only common files for
>> both versions so it will be overwritten by the later installation or
>> upgrade. Or not?
>
> This is an automated step to allow the python ports to be installed for
> more than one python version at the same time. The scripts in
> /usr/local/bin being one of the places that a conflict can happen. Docs
> and licenses are other paths that can conflict, these other dir names
> are altered to match the python version. eg share/licenses/py-pip will
> get changed to share/licenses/py27-pip
>
> In the Makefile of the port USE_PYTHON=concurrent enables this feature,
> if a port conflicts with multiple python versions then concurrent needs
> to be added (or sometimes other adjustments). If you remove concurrent
> then the symlinks in bin won't be made.
>
> I don't think there is a way to control this with environment variables
> so you would have to alter the ports Makefile and build yourself if you
> want it to work differently.
>
> The reason for the symlink is to allow the expected pip script to exist
> in bin while preventing multiple python versions conflicting, the pkg
> installed for the default version of python will own the bin/pip which
> will symlink to it's install of bin/pip-${PYTHON_VER} - pkgs installed
> for other versions of python will only install bin/pip-${PYTHON_VER}
>
> So if python 2.7 is the default version, py27-pip will install bin/pip
> and bin/pip-2.7 while py34-pip will only install bin/pip-3.4
> If you run pip you will get the default py27 version but if you want to
> run it for py34 then you need to specifically run pip-3.4
>
> You can alter the default python version by adding to /etc/make.conf
>
> DEFAULT_VERSIONS= python=2.7 python2=2.7 python3=3.4
>
> And if your wondering how to build multiple versions -
>
> cd /usr/ports/devel/py-pip
> make PYTHON_VERSION=3.4 install clean

Thank you for your detailed explanation. I will play with
'make PYTHON_VERSION=3.4 install clean' :)

Miroslav Lachman