[reidrac]

So far I've focused on making new projects both Python 2 and 3 compatible, but "new stuff" in Python 3 is not always available when:

- Laptop running Ubuntu Trusty: Python 3.4

- Production servers with Debian Wheezy: Python 3.2

- Laptop running Fedora 20: 3.3.2

You don't usually install Python in Linux using upstream, you install the version provided by your distribution and unfortunately Python 3 has differences between these versions (eg, "yield from" was introduced in 3.3, IIRC), whilst 2.7.x it's been without changes for a long time.

Even Apple includes 2.7 now (handy when I distribute a game made with Pyglet); so I'm excited too, but Python 2 still makes my life easier.

[cookiecaper]

Python is actually much better than almost all equivalent languages in this. Consider that custom package managers like rvm/bundler, nvm/npm, etc., are considered must-haves for any kind of serious development on Ruby or Node, whereas use of virtualenv is still kind of seen as a "bonus" feature. The fact that Python is good enough to allow that demonstrates its robustness.

Stop using Python 2. All of the justifications I'm seeing in this thread are complete non-starters. If you want to use a 3.3 feature, install Python 3.3. Are you seriously suggesting that we revert to the problems of 2.x, discarding all the effort that's been dumped into Py3 compat over the last 7 years, because you don't want to install a software package? It's really common to need to add extra sources to a package manager for new versions of things, and it's also common to need to build your own packages. It shouldn't be that hard. Be grateful that at least there's a possibility you can use the system Python, since Ruby communities don't really have that luxury.

[palmstroem]

After we migrated to Python 3, we came to regret the decision with considerable regularity. We mostly use MacOS, and working with OpenGL and scientific libraries has been painful. We never found that a library we needed was not available for 2.7, but lots of stuff has not been ported to 3.3. The syntactic advantages of 3 have been too minor to warrant the troubles we earned. Your mileage may vary, if you have different applications, of course.

[eeZi]

Debian Jessie and Fedora 21 both ship Python 3.4, so that problem is going away.

In the meantime, it's always possible to install a self-contained Python 3.4 interpreter and a virtualenv. It's pretty straight-forward, actually. The only thing you'll miss is distribution-provided binary packages (like lxml), but pip/setuptools compiles them for you.

[eeZi]

Refer to this comment for an alternative way to install Python 3.4 without compiling it yourself: https://news.ycombinator.com/item?id=9389742

[raverbashing]

You can install the binaries with a Virtualenv (at least on 2.X, virtualenv on 3.x is a pain until 3.4)