[Development] Why does QFactoryLoader and QLibrary cache information in QSettings?

[Frans Klaver]

On Tue, 25 Oct 2011 21:38:25 +0200, Chris Meyer <cmeyer1969+qt at gmail.com>  
wrote:

> Why does QFactoryLoader and QLibrary cache information in QSettings?
>
> Does this cache information need to be available between application  
> launches?
>
> Is there a performance reason?

As I always understood (from the docs), the plug-in information is stored  
in QSettings to speed up validation in between runs. So the first run  
would take slightly longer to start up than consecutive runs.


> Are the reasons different from platform to platform?

Not likely.


> Could the use of QSettings be replaced with a local QMap object?

I don't think this would add value, unless certain things are queried more  
often. I would expect a local variable to be sufficient.

You could probably sneak around this by specifying a custom format  
(QSettings::registerFormat()[1]) and provide read/write functions that  
don't access disk. Then QSettings::setDefaultFormat()[2] to the resulting  
value.

Hope this helps.

Cheers,
Frans

[1] http://doc.trolltech.com/latest/qsettings.html#registerFormat
[2] http://doc.trolltech.com/latest/qsettings.html#setDefaultFormat