[gtk-osx-users] Python3

[John Ralls <jralls ceridwen us>]

The Gnome developers are moving towards a Python 3 environment while Apple at least for now remains stuck in 
Python 2. (WWDC 2018 starts in an hour or so, but even if MacOS 10.14 will finally start distributing Python 
3 there’s still several years of supporting older versions ahead of us.)

Several packages in the Gnome stack have dropped autotools support in the last several months in favor of the 
Meson build system, and the Meson build system requires Python 3. An additional complication is that it’s 
becoming more common for packages to require Python modules that are distributed primarily or even only via 
PyPI, e.g. gtk-doc requires Six for Py2/3 compatibility.

So going forward gtk-osx needs a Python 3 and PyPI-friendly environment in which to run. While investigating 
that yesterday I found https://docs.pipenv.org/. This can be bootstrapped with curl from its Github repo and 
works with Python2. A pair of configuration files, Pipfile and (poorly named, it's not a lock file) 
Pipfile.lock, specify the python version and necessary PyPI packages.

I propose that gtk-osx-build-setup.sh would bootstrap Pipenv, install a Pipfile and Pipfile.lock with the 
requisite dependencies, start up Pipenv, and install jhbuild into the Pipenv environment. One would run 
jhbuild in a Pipenv shell; that could be made more-or-less transparent with a simple script file or shell 
alias.

Thoughts?

Regards,
John Ralls