SourcePro : Essential Tools Module User's Guide : Persistence : A Few Friendly Warnings : Don't Use Sorted RWCollections to Store Heterogeneous RWCollectable Objects
Don't Use Sorted RWCollections to Store Heterogeneous RWCollectable Objects
When you have more than one different type of RWCollectable stored in an RWCollection, you can't use a sorted RWCollection. For example, this means that if you plan to store RWCollectableStrings and RWCollectableDates in the same RWCollection, you can't store them in a sorted RWCollection such as RWBTree. The sorted RWCollections are RWBinaryTree, RWBTree, RWBTreeDictionary, and RWSortedVector.
The reason for this restriction is that the comparison functions for sorted RWCollections expect that the objects to be compared to have the same type.