Projects/Marble/GeoData/PointerVsImplicitShare

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Revision as of 14:29, 31 March 2010 by Bholst (Talk | contribs)

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Implicit sharing and storing objects as value is very reasonable for basic data as QStrings, but there are reasonable doubts regarding Placemarks and other GeoData. There are some possibilities:

  • Don't use implicit sharing at all and store all objects on the heap with a pointer to it.
  • Use implicit sharing and storing as value for GeoDataCoordinates only.
  • Use implicit sharing and storing as value for all GeoData classes.

To find out which is the wisest I try to look at every single class:

Base data

  • GeoDataCoordinates This one is quite simple. It is not more than a QPoint in GeoCoordinates. This should stay implicilty shared.
  • GeoDataLatLonBox (GeoDataObject) It seems to nothing more than a QRect for GeoCoordinates. I'm not sure if it must be derived from GeoDataObject
    • GeoDataLatLonAltBox same for this

Geometric structures

  • GeoDataGeometry The base class for all geometric. We could want a pointer for this, so using it as data may not be the right way.
    • GeoDataPoint This one uses multiple inheritance (GeoDataCoordinates). I don't think that this is semantically correct.

views

  • GeoDataAbstractView It's nothing more than a view, this could stay implicitly shared.
    • GeoDataLookAt Same for this as this is a child.

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