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Multiple versions of the same package installed at same time

Multiple versions of the same package installed at same time

Posted Nov 13, 2009 12:19 UTC (Fri) by Cato (subscriber, #7643)
Parent article: Python moratorium and the future of 2.x

Perhaps the real issue here is that Linux's excellent package management make it significantly harder to installed a 'second' version of Python, or in fact any package. You either need to compile from source, or install a binary under a tree that doesn't affect the core package, or do a chroot-install, or something else that's equally complex.

Windows often makes this a lot simpler, although sometimes the registry enforces single versions. At least without dependency management it's easier to install the same version twice using a simple installer.

While package management makes things simpler, if there was an easier way to install two versions of Python and choose which applications use which version, you could make a gradual transition to Python 3 without breaking core distro features.

Am I missing something here?


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Multiple versions of the same package installed at same time

Posted Nov 13, 2009 12:49 UTC (Fri) by rahulsundaram (subscriber, #21946) [Link]

Programs have to be designed to be parallel installable. There are applications and libraries which do make this very easy. GTK and gstreamer comes to mind.

Details at http://www106.pair.com/rhp/parallel.html

Multiple versions of the same package installed at same time

Posted Nov 13, 2009 15:49 UTC (Fri) by roblucid (subscriber, #48964) [Link]

Yes, I think you are. Basically if you build an RPM, it does the ./configure; make && make install. Geerally FOSS packages default to /usr/local and distro's configure them to be rooted at /, /usr, /opt whatever.

So in fact you ought to be able to be able to build Gen++ packages, rooted at a different place than Gen, and select which implementation you use by traditional means $PATH & environment.

Opening up openSUSE 11.2 Software Package manager, and I find :

python -2.6.2-6.3
python-32bit -2.6.2-6.2
python3 -3.1-3.3

So perhaps Distro's with good package managers are not the problem at all.
Whoops I just installed python3 without really meaning to, expecting it to tell me about other packages it would require installed to with it.

I have both installed, guessing it'll be python3 :

ladm@fir:~/.kde4/share/config> python3
Python 3.1 (r31:73572, Oct 24 2009, 05:39:09)
[GCC 4.4.1 [gcc-4_4-branch revision 150839]] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>

Multiple versions of the same package installed at same time

Posted Nov 13, 2009 16:18 UTC (Fri) by Cato (subscriber, #7643) [Link]

I think you've made my point for me, which was that installing a second
version is significantly more complex than just installing the default
version.

I'm aware that some distros create 'python3' packages, but that's really a
hack rather than a general solution - why isn't it possible to pull a newer
version of Python from a later version of the distro (e.g. Ubuntu 9.10 while
using an earlier version of Ubuntu), and cleanly install it with
dependencies, maybe in a dynamically created chroot or simply a new directory
prefix.

Multiple versions of the same package installed at same time

Posted Nov 14, 2009 17:35 UTC (Sat) by man_ls (guest, #15091) [Link]

It is better this way, I think. I don't want a second set of the same libraries lying around; if I did I would do the chroot myself. It does not look like a hack to me, at least on Debian.
# ls -l /usr/bin/python
lrwxrwxrwx 1 root root 9 jul 17 01:48 /usr/bin/python -> python2.5


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