KConfig and KGlobalSettings (user settings for widgets)

[David Faure]

On Tuesday 13 March 2012 22:04:18 Alexander Neundorf wrote:
> There it is quite similar: do we just provide independent libraries, where 
> every developer can/must take care that the libraries follows KDE
> conventions  how it is built and installed, or do we provide some common
> thing everybody uses, and so everything fits together as it should.

I know that you're struggling with this topic at the moment, but I actually 
think the answer is "it depends".

At the lowest level, we provide functionality that is completely independent: 
karchive is the best example. No configuration needed there.

sonnet is also an interesting example: you could have a spellchecker that is 
entirely configured by the application, or a spellchecker that actually knows 
the default language for the current user (which is better integration) ... 
and actually Qt does know the current language(s). So this kind of destroys 
the argument in my previous email... Qt, too, can use user settings.

What's more difficult is when KDE wants more configurability than Qt :-)
(e.g. "show icons on pushbuttons").
The Qt solution to such things is more commonly a widget style hint, for 
instance. Heh... wait... oh... it exists already:
style()->styleHint(QStyle::SH_DialogButtonBox_ButtonsHaveIcons)

There goes another argument down the drain. This is the proper solution, not 
KGlobalSettings. The widget style that implements this style hint can read 
user settings, that's fine.
kdeui/kstyle.cpp even does that, calling KGlobalSettings. Bingo :-)

Thanks for making the opposite point, it made me look further into it :)
I'll fix KPushButton accordingly.

This is another case where notification isn't needed, the setting is used when 
creating new push buttons.

To summarize: as discussed before, we want the API to be "standard Qt", and 
the behavior to be "KDE-specific" where appropriate (e.g. respecting the 
settings of the KDE user). With all the "callbacks" in Qt (platform plugin,
widget style, etc.) it's not impossible to do, even though it's more work than 
simple subclasses (e.g. of widgets), obviously.

-- 
David Faure, faure at kde.org, http://www.davidfaure.fr
Sponsored by Nokia to work on KDE, incl. KDE Frameworks 5