[Scons-dev] Python 3 strategy

[Russel Winder]

I am having difficulty making a decision…

The earlier Python 3 branch is founded on using six. At the time a good
decision. Now however we have agreed that 2.7 is the base version and
thus future rather than six is the better tool for Python 3. This
brings into doubt the python3-port branch as a good base of operations.

William has done some work changing the python3-port branch, as have I,
all based on the massive previous work. Despite all this effort I
wonder if we have the right base to progress further. Maybe we have and
carry on, but now is the time to stop before much more effort goes in
if this is not the way forward.

The alternative is to abandon the current python3-port and start again
from default based solely on future.

Instead of having a separate branch, let us work solely on default,
turning it first into a Python 2.7 only thing using futurize to prepare
the ground. This is really an extension of what is currently happening
of course, but with a turbo charger. Let us insist that the SCons
default branch is "futurize -1" with all __future__ imports in place,
so that all Python 2.7 code is using Python 3 semantics where
possible. 

This can happen within the current infrastructure effectively
unchanged. Obviously all CI should be green with each changeset. I
suspect it will not run under Python 3 in this form.

When this is done, we can add the "futurize -2" with the dependency on
future, obtained not by vendorizing but by package management install.
This should leave the Python 2.7 CI still green – assuming all the CI
servers have future installed. (With Codeship and Drone this is handled
by using a requirements.txt file in the usual pip-ish way.) Then the
work of getting a Python 3 CI green can happen, with the Python 2.7 CI
always green.

Of course even though the Python 2.7 tests are red, and the Python 3
tests do not run, python3-port on Python 3.5 and 2.7 actually works.
This is the opposite side of the coin, why change strategy now?
 
 
-- 
Russel.
=============================================================================
Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder at ekiga.net
41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel at winder.org.uk
London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder

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