major overhauls in plasma declarative for dataengines

[Marco Martin]

On Friday 23 September 2011, Aaron J. Seigo wrote:
> hi all...
> 
> last night i committed to master in kde-runtime some major changes to the
> code that handles the briding of Plasma::DataEngine into QML. there was
> some complexity in there that was unnecessary and some performance
> improvements to be found as well.
> 
> there is still an issue with performance left that i'm not 100% sure yet
> how to deal with: DataSource keeps a local copy of all
> Plasma::DataEngine::Data ... which means that when the Data changes, it
> will cause a bunch of allocations as data members get detached, which then
> gets all thrown away instantly when dataUpdated gets called.

yeah, that was always my major gripe with datamodel.. i don't see much other 
ways with plasma1 tough..

a thing that could be done is try to share 100% the data copies of DataSource 
and DataModel.

> in any case, i'm not comfortable backporting this to the KDE/4.7 branch
> right now. it's functionally equivalent to the old code, so no majorly
> disruptive changes (Marco: i ended up putting the source filter back in),

reason? ;)

> but it needs more testing.
> 
> if you are using kde-runtime from master with QML, please try to keep an
> eye out for any anomolies related to dataengines.
> 
> everything is working perfectly here, but i may have missed something.

yeah, i'll give a try and will take a look at the overall diff

-- 
Marco Martin