Kdelibs Coding Style vs. preparations for Qt5

[Kevin Ottens]

On Saturday 29 December 2012 16:25:54 Albert Astals Cid wrote:
> El Dissabte, 29 de desembre de 2012, a les 10:48:48, Kevin Ottens va 
escriure:
> > Hello,
> > 
> > On Saturday 29 December 2012 02:47:13 Friedrich W. H. Kossebau wrote:
> > > --- 8< ---
> > > Qt Includes
> > > 
> > > If you add #includes for Qt classes, use both the module and class name.
> > > This allows library code to be used by applications without excessive
> > > compiler include paths.
> > > 
> > > Example:
> > > // wrong
> > > #include <QString>
> > > 
> > > // correct
> > > #include <QtCore/QString>
> > > --- 8< ---
> > > From http://techbase.kde.org/Policies/Kdelibs_Coding_Style#Qt_Includes
> > 
> > Since I've been skimming quite a bit through kdelibs codebase recently,
> > needless to say this rule is in practice void as it's clearly not
> > followed.
> > 
> > > Of course the current Qt Coding Style, which is the base of the kdelibs
> > > one, does not mention anything about that, given that its about their
> > > own
> > > headers.
> > 
> > Yep.
> > 
> > > Now the Porting from Qt 4 to Qt 5 guide from KDAB recommends this:
> > > --- 8< ---
> > > Fixing up includes
> > > 
> > > [...]
> > > 
> > > Or more portably (Which works in Qt 4 and Qt 5):
> > > #include <QWidget>
> > > --- 8< ---
> > > From http://www.kdab.com/porting-from-qt-4-to-qt-5/
> > > 
> > > 
> > > So what to do about this?
> > 
> > I *personally* prefer the fully qualified style with the module name. That
> > said, since we don't have per module namespaces to go with it and the like
> > it's rather cosmetic more than anything. Now add to that the fact that the
> > fully qualified style will generate more work when you port (for classes
> > moving from one module to another) it sounds like it's the right move to
> > drop them completely and use only the class name for includes[*].
> > 
> > > Will kde-frameworks be Qt5-only, so not need to support both Qt4 and Qt5
> > > and thus to use module-less Qt includes?
> > 
> > For now it supports both, but it's very likely that by the end of january
> > it will be Qt5 only.
> > 
> > > Or will the includes be if-def'ed? So will projects which refer to the
> > > Kdelibs Coding Style need to add an exception to their rules for the
> > > includes, if they want to prepare for Qt5?
> > > 
> > > Or does the rule need adaption?
> > 
> > With what I wrote above I think the natural conclusion is to adapt the
> > rule. We should push to use the class name only includes I think.
> > 
> > Also, contributing to Qt itself more, I noticed some differences in style
> > between both (namely: we ignore space around operators, and we for braces
> > around single line statements). Your question makes me wonder if we should
> > update our own KDE Frameworks style to be closer of the Qt one. The aim
> > here would be to be consistent accross the whole stack.
> > 
> > Actually looking at both documents now, I see we should already follow the
> > spacing around operators today... I think the intent of our coding style
> > was to be "the Qt style with extra exceptions" but somewhere in the
> > wording this gets lost. Maybe we should do a better job at it... If we go
> > toward being closer to the Qt style maybe the proper way out would be to
> > shorten the document quite a bit saying: use the Qt style + includes
> > section + astyle section + emacs & vim section. Right now by duplicating
> > some but not all of the Qt style we're diluting the messaging it seems.
> > Opinions?
> > 
> > Thanks for bringing it up though, it's definitely the right time for that.
> 
> Would there be any chance to have the style check done by a pre-commit hook?
> Or at least have a command-line tool that checks it for me?

If anyone is willing to put the time and effort I would definitely welcome 
that!

But it clearly need some more investigation (use krazy or astyle? how much 
setup for dev? how reliable? etc.) and experimentation.

> Personally I find it is quite hard to remember all the different coding
> styles of the bazillion projects I controbiute to and since i can't
> remember they in my head i have to find the page that describes the coding
> style and check it manually each time i want to contribute to the
> respective projects, and to be honest that is quite boring and lowers my
> morale.

Yep, that's one more reason for trying to be closer to the Qt style as I 
mentioned in my previous email. But I'm waiting to see if someone has 
practical problems with such a move to have a clearer opinion.

Regards.
-- 
Kévin Ottens, http://ervin.ipsquad.net

KDAB - proud patron of KDE, http://www.kdab.com
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