Open Stack

On Wed, Jan 29, 2014 at 01:22:59PM -0500, Joe Gordon wrote:
> On Tue, Jan 28, 2014 at 4:45 AM, John Garbutt <john at johngarbutt.com> wrote:
> > On 27 January 2014 10:10, Daniel P. Berrange <berrange at redhat.com> wrote:
> >> On Fri, Jan 24, 2014 at 11:42:54AM -0500, Joe Gordon wrote:
> >>> On Fri, Jan 24, 2014 at 7:24 AM, Daniel P. Berrange <berrange at redhat.com>wrote:
> >>>
> >>> > Periodically I've seen people submit big coding style cleanups to Nova
> >>> > code. These are typically all good ideas / beneficial, however, I have
> >>> > rarely (perhaps even never?) seen the changes accompanied by new hacking
> >>> > check rules.
> >>> >
> >>> > The problem with not having a hacking check added *in the same commit*
> >>> > as the cleanup is two-fold
> >>> >
> >>> >  - No guarantee that the cleanup has actually fixed all violations
> >>> >    in the codebase. Have to trust the thoroughness of the submitter
> >>> >    or do a manual code analysis yourself as reviewer. Both suffer
> >>> >    from human error.
> >>> >
> >>> >  - Future patches will almost certainly re-introduce the same style
> >>> >    problems again and again and again and again and again and again
> >>> >    and again and again and again.... I could go on :-)
> >>> >
> >>> > I don't mean to pick on one particular person, since it isn't their
> >>> > fault that reviewers have rarely/never encouraged people to write
> >>> > hacking rules, but to show one example.... The following recent change
> >>> > updates all the nova config parameter declarations cfg.XXXOpt(...) to
> >>> > ensure that the help text was consistently styled:
> >>> >
> >>> >   https://review.openstack.org/#/c/67647/
> >>> >
> >>> > One of the things it did was to ensure that the help text always started
> >>> > with a capital letter. Some of the other things it did were more subtle
> >>> > and hard to automate a check for, but an 'initial capital letter' rule
> >>> > is really straightforward.
> >>> >
> >>> > By updating nova/hacking/checks.py to add a new rule for this, it was
> >>> > found that there were another 9 files which had incorrect capitalization
> >>> > of their config parameter help. So the hacking rule addition clearly
> >>> > demonstrates its value here.
> >>>
> >>> This sounds like a rule that we should add to
> >>> https://github.com/openstack-dev/hacking.git.
> >>
> >> Yep, it could well be added there. I figure rules added to Nova can
> >> be "upstreamed" to the shared module periodically.
> >
> > +1
> >
> > I worry about diverging, but I guess thats always going to happen here.
> >
> >>> > I will concede that documentation about /how/ to write hacking checks
> >>> > is not entirely awesome. My current best advice is to look at how some
> >>> > of the existing hacking checks are done - find one that is checking
> >>> > something that is similar to what you need and adapt it. There are a
> >>> > handful of Nova specific rules in nova/hacking/checks.py, and quite a
> >>> > few examples in the shared repo
> >>> > https://github.com/openstack-dev/hacking.git
> >>> > see the file hacking/core.py. There's some very minimal documentation
> >>> > about variables your hacking check method can receive as input
> >>> > parameters
> >>> > https://github.com/jcrocholl/pep8/blob/master/docs/developer.rst
> >>> >
> >>> >
> >>> > In summary, if you are doing a global coding style cleanup in Nova for
> >>> > something which isn't already validated by pep8 checks, then I strongly
> >>> > encourage additions to nova/hacking/checks.py to validate the cleanup
> >>> > correctness. Obviously with some style cleanups, it will be too complex
> >>> > to write logic rules to reliably validate code, so this isn't a code
> >>> > review point that must be applied 100% of the time. Reasonable personal
> >>> > judgement should apply. I will try comment on any style cleanups I see
> >>> > where I think it is pratical to write a hacking check.
> >>> >
> >>>
> >>> I would take this even further, I don't think we should accept any style
> >>> cleanup patches that can be enforced with a hacking rule and aren't.
> >>
> >> IMHO that would mostly just serve to discourage people from submitting
> >> style cleanup patches because it is too much stick, not enough carrot.
> >> Realistically for some types of style cleanup, the effort involved in
> >> writing a style checker that does not have unacceptable false positives
> >> will be too high to justify. So I think a pragmatic approach to enforcement
> >> is more suitable.
> >
> > +1
> >
> > I would love to enforce it 100% of the time, but sometimes its hard to
> > write the rules, but still a useful cleanup. Lets see how it goes I
> > guess.
> 
> I am weary of adding any new style rules that have to manually
> enforced by human reviewers, we already have a lot of other items to
> cover in a review.

A recent style cleanup was against config variable help strings.
One of the rules used was "Write complete sentances". This is a
perfectly reasonable style cleanup, but I challenge anyone to write
a hacking check that validates "Write complete sentances" in an
acceptable amount of code. Being pragmatic on when hacking checks
are needed is the only pratical approach.

Regards,
Daniel
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