Phyton

[Chris Angelico]

On Mon, Mar 7, 2016 at 5:45 PM,  <marco.nawijn at colosso.nl> wrote:
> As a side note, you are probably aware that if you look at the Linux
> ecosystems there are still a lot of distributions that have Python 2
> as a default. There are still also large mainstream libraries that
> do not (or just very recently) have support for Python 3. For me this
> in particular applied to VTK. I am now finally ready to move to Python 3.

There aren't many mainstream libraries that are still being developed
and don't support Python 3 and don't have equivalents that support
Python 3. There are a reasonable number of third-party modules that
are basically "hey folks, here's the bindings for C++, here's the
bindings for Java, and here's the bindings for Python", where "Python"
has for years meant Py2 only; from what I see of VTK, that seems to be
the case. (It's true of the Google API module, too.) The only way to
get this sort of thing to change is to show these companies that there
is real demand for Python 3 support.

As to Linux distros having Py2 as default - there are two separate
things here. One is that the name "python" will run Python 2, and
Python 3 has to be invoked as "python3". That's stipulated by PEP 394,
and won't be changing. The second concept is of packages being
installed by default, and/or being depended on by critical services.
At the moment, that's more Py2 than Py3, but several distros are
working on migrating (Ubuntu tried hard to have 14.04 ship without Py2
on the main CD ISO, but failed; not sure where they're at now, but
it's definitely the plan), and that's going to start shifting. But for
an application developer, it hardly even matters. If you ship Ruby
code, you declare a dependency on Ruby; if you ship Python code, you
declare a dependency on either Python 2 or Python 3, or "python-any"
or somesuch if you're compatible with both. It's easy enough to have
both Pythons installed on every Linux system that I've ever worked on,
and I rather doubt that that will change.

ChrisA