[Python-Dev] Backport troubles with mercurial

Stephen J. Turnbull stephen at xemacs.org
Thu Dec 30 06:42:48 CET 2010

R. David Murray writes:

 > We merge bug fixes to 2.7 on a routine basis.  It is the rule rather
 > than the exception, by a long shot.

For bugfixes, of course it's routine.  I understand that.  My point
was that the case Amaury fears, where the (new) VCS makes things
harder than patching or porting by hand, is likely to be relatively
uncommon, sandwiched between the "typo fixed in comment" conflicts
(aka "trivial tweaks") and those that require reengineering.

Also, while workflow helpers will make a big difference to the
non-VCS-geeks (ie, almost all Python developers), properly speaking
this isn't really an issue with Mercurial, because all of the methods
for this purpose are basically "diff | patch", although the
executables are called things like "svn" and "python".  They all
demand workflow helper scripts to regulate the flow of desired and
undesired patches.  The difference is that the tool for hg is a SMOP,
while that for svn is a SMOEP[1].

 > So, since we are going to be maintaining 2.7 for a while, this is
 > a workflow problem that we *must* solve to make the hg transition
 > worthwhile.  I have no doubt that we will, but I also have no doubt we
 > need to *solve* it, not just wave our hands.

Certainly.  I think I already said that, no?  My point is simply that
while Amaury's expression of his requirements is welcome, and his
experimenting with hg is extremely valuable, indeed a necessary part
of the transition, everything he describes so far is a known problem
that we basically know how to solve.  He talks about changes to the
workflow, but frankly, I don't see a *need* for that.[2]

IMO, changes to the workflow will be driven by kaizen, not by some
brave new world revolution (Guido inter alia insisted on that) nor by
thumb-in-dike disaster recovery (PEP 374 did a pretty good job on
that, if I do say so myself).

I wish I had more time to do real work on this (not to mention email,
thank *you*, David!), but it seems like every time I start
programming, I fall asleep ... and six hours later, it's back to day
job or family services. :-/

[1]  Simpler Matter Of Existing Program.

[2]  Aside for a need for establishing which hg commands correspond to
which parts of the existing workflow, and perhaps creating helper
scripts.  Ie, I think the chances are pretty good that most people who
have already tried hg are at least a little VCS-geeky, and probably
they adjust personal workflow to the new VCS.  That will not be so
transparent to the "the tool should work for me, not vice-versa"

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