Open Stack

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.

John