Review Request: Add hasItem(..) function to Extender

[Rob Scheepmaker]

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http://reviewboard.kde.org/r/277/
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Review request for Plasma.


Summary
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Because ExtenderItems are persistent between sessions, applet's that use extenders can't just blindly add ExtenderItems without checking if that item is already there. The problem with using Extender's item(..) function for this check, is that while plasma is starting, not all detached items might have been instantiated already. This could lead to duplication of extender items. For example: the way we currently solve this in libplasmaclock is by using a single shot timer in init, so we give all extender items a chance to load before we check if we already have a calendar.
With this patch that is no longer necessary. Besides the item(..) function we have an hasItem(..) function that checks if the item exists at all, even if it has not yet been instantiated. The way this works, is that every detached item also gets an entry in a special DetachedItems section in the appletrc. This entry contains just the name, id, and source applet, so we can scan that information in hasItem(...) and get the desired behavior.
This might be optimized a bit in the future (it's global, so we only have to scan that section once and cache the results), but currently the amount of extender items that are being used is not that big.


Diffs
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  /trunk/KDE/kdebase/workspace/libs/plasmaclock/clockapplet.cpp 938402 
  /trunk/KDE/kdelibs/plasma/extender.h 938402 
  /trunk/KDE/kdelibs/plasma/extender.cpp 938402 
  /trunk/KDE/kdelibs/plasma/extenderitem.cpp 938402 

Diff: http://reviewboard.kde.org/r/277/diff


Testing
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Replaced the single shot timer hack  for the calendar in libplasmaclock with a hasItem call. Works perfectly.


Thanks,

Rob