Coding standard for qdebug in libs

[Jaroslaw Staniek]

On 5 September 2015 at 13:41, Boudewijn Rempt <boud at valdyas.org> wrote:
> There is one more thing about logging using qCDebug and friends:
> the logging categories are supposed to be defined _per library_.
>
> Which is actually pretty useless and not really how we've been
> using categories in Calligra. Logging categories for file
> handling, resource management or plugin handling that can be used
> across libraries and applications make it possible to focus on
> debugging a path through the application's execution.
>
> I don't debug pigment, I debug color management, for instance, which
> is present in pigment, the colorspace plugin and parts of Krita.
>
> That's why for Krita, I made a generic debug interface in a little
> global library that knows about all the categories and that can
> be used from everywhere.

Yeah that's OK too, case by case. Names for these cross-libs
categories can be invented too.

Similarly, for database-reladed stuff we even have a GUI logger:
http://i.imgur.com/9bfljqF.png


> Oe Sat, 5 Sep 2015, Jaroslaw Staniek wrote:
>
>> Hi,
>> This is a proposal for some consistency for naming of debug functions,
>> debug headers and logging categories.
>> I'll be trying to achieve in code I maintain. I can put some
>> guidelines on the dev wiki.
>>
>> Details:
>> After looking at recent commits such as Friedrich's 1dddbcdbceab0
>> "kWarning -> warnPigment" I was wondering if we want to have standards
>> for debug handling.
>> I don't use one in Kexi, not yet, but use one in
>> kdb/kreport/kproperty. With increasing modularity it's quite important
>> for our debugging needs to have logging categories.
>>
>> A scheme could be like
>> {libnamelowercase}{Debug|Warning|Critical}()
>>
>> e.g. I use kdbDebug() << ... ;
>>
>> Note, for clarity () is used here too like in qDebug().
>> See kdb_debug.h
>> https://quickgit.kde.org/?p=kdb.git&a=blob&f=src%2Fkdb_debug.h
>>
>> Furthermore, in kde_debug.cpp
>> [https://quickgit.kde.org/?p=kdb.git&a=blob&f=src%2Fkdb_debug.cpp] I
>> have:
>> Q_LOGGING_CATEGORY(KDB_LOG, "org.kde.kdb.core")
>>
>> Note that you can pick your scheme for string, e.g.
>> org.kde.calligra.{someapp} or org.calligra.{someapp}
>> and for libs org.kde.{somelib}. It's important to have it unique and
>> relatively short. Planning for future expansion is a good way too.
>>
>> For tests and example apps it may be enough to use default debug or
>> for big code decide to add special category too.
>>
>> I also propose to use a libname prefix for the header name. This is
>> what many bits in KF5 do. So we won't have to deal with dozens files
>> prefixed with "Debug" soon (so libpigment's DebugPigment.h could
>> become PigmentDebug.h or pigment_debug.h).
>>
>> PS: I am aware e.g. KF5 has various approaches there, use qDebug()
>> with no categories, use qCDebug without defines.
>> We have not fully migrated to logging categories in apps and internal
>> libs so I thought it may be cool to think about consistency early
>> enough.
>>
>> --
>> regards, Jaroslaw Staniek
>>
>> KDE:
>> : A world-wide network of software engineers, artists, writers,
>> translators
>> : and facilitators committed to Free Software development - http://kde.org
>> Calligra Suite:
>> : A graphic art and office suite - http://calligra.org
>> Kexi:
>> : A visual database apps builder - http://calligra.org/kexi
>> Qt Certified Specialist:
>> : http://www.linkedin.com/in/jstaniek
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>
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-- 
regards, Jaroslaw Staniek

KDE:
: A world-wide network of software engineers, artists, writers, translators
: and facilitators committed to Free Software development - http://kde.org
Calligra Suite:
: A graphic art and office suite - http://calligra.org
Kexi:
: A visual database apps builder - http://calligra.org/kexi
Qt Certified Specialist:
: http://www.linkedin.com/in/jstaniek