Queue Manager

[furt at gmx.de]

> Datum: Mon, 01 Feb 2010 08:12:04 -0500
> Von: Jeff Mitchell <mitchell at kde.org>
> On 01/31/2010 08:06 PM, furt at gmx.de wrote:
> > Concerning the actual implementation: currently I use a very basic
> approach by
> > simply polling TrackNavigator::queue() from within a QueueEngine and
> Anytime you use the word "polling" and you're not talking about device
> drivers, you're probably doing something wrong. These days, even if you
> are writing device drivers, you might very well be doing something wrong
> anyways.  :-)

Thanks, I know that of course. But as I said, I am new to kde programming, and I just wanted to get in touch with plasma programming and get some visible results to prove that my understanding of displaying things in plasma (for the context view) was correct - so I used the possibility of the Plasma::DataEngine to poll, so that I didn't have to change any code in any amarok classes in the first iteration.

> Why not emit a signal when the queue is modified, and connect that
> signal to a slot in your manager?

As far as I understand, plasma applets should use a data engine to access any data ( http://techbase.kde.org/Development/Tutorials/Plasma#Plasma_Programming_with_C.2B.2B ). That's the reason why I wrote the QueueEngine. That one of course, could connect to a Signal. But I've had a look at the AlbumsApplet and the CurrentApplet, which both use an observer to observe the playlist or the current track. The observer lives in amaroklib, and only that observer would have to be exported from amaroklib, so it can be used from the plasma applets. If I wanted to connect to the queue directly, the TrackNavigator would have to exported - I don't know about the policy to export arbitrary classes... and of course, there would be problems when the track navigator changes, e.g. when the playmode is switched from random to dynamic mode.

-Marius
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