Support different Python versions for child execution

[facundobatista]

This will be automatically decided by fades being executed like 'fades' or 'fades3', or 'fades2.7', etc...

[facundobatista]

Actually, that's not the best idea:

• it's obscure that that number controls the python version
• it complicates our operatory (for example: if you install fades in a system that only has python3, and later the user installs python2, there will be a fades2.7 in /usr/bin?)

So, using a parameter -p/--python that accepts the number (2.7) or the whole name (python2.7) or the whole path (/usr/bin/python2.7) is more explicit, safe, and easy

[gilgamezh]

@facundobatista I need some help here.

First of all I think that this branch needs a merciless code review ;) https://github.com/PyAr/fades/compare/different_interpreter_versions

Then:

• How can I 'upgrade' de venvs database?
• How can I test to create a venv with virtualenv? Mocking logged_exec()

[facundobatista]

In fades/envbuilder.py:

• create_with_virtualenv has no docstrings

• don't do this:

  args = args[:3] + ['--no-pip'] + args[3:]

  (use args.insert)

• the try/except you created is too big, you're wrapping too many different lines inside; do a try/except ImportError for the import, and then a try/except fr the command execution (not the args building, etc)

• why this and not executing 'virtualven' directly?

  virtualenv_exe = sys.executable.replace('python', 'virtualenv')

In fades/helpers.py:

• don't do this:

  "{}/{}".format(path, file))

  (use os.path.join)

• 'which' function has no docstring
• 'get_interpreter_version' has a docstring with first line not a single line.

• don't do:

  if not '/' in requested_version:

  do:

  if '/' not in requested_version:

• I don't understand this:

  if not any([char.isdigit() for char in requested_version]):

  because that code is important if user passed "python" or "python2", no matter the number

In general:

• you're considering the file name for the 'interpreter', like in the following line:

  interpreter = sys.executable.split('/')[-1]

  this breaks in the situation when /usr/bin/python and /usr/local/bin/python and /home/development/python are different...

• tests failed:

  http://linkode.org/5Rh9fz5Xe2XQ4QgtVLyEQ1

[gilgamezh]

Test are failing I'm working in it. I think that we can release this week. :smile: