Caveats to using KeyPtr's

Once you create a KeyPtr referring to an object, the TPhKeyManager thinks it 'owns' the object, and might delete it out from under you (if you've discarded your KeyPtr), or might give someone else a pointer to that object without telling you. Here are some rules to follow when working with KeyPtrs:

• Don't make KeyPtr's to objects which are not now or soon to be stored in the database.
  The current implementation forbids this, but that may change in the future.
• Don't change an object pointed to by a KeyPtr unless you know what you must.
  The current implementation also forbids this, but this may change since there are too many ROOT functions which are not const-correct. If it is changed, changing the object a KeyPtr points would cause others hard-to-find bugs.
• Don't take pointers to the object pointed to by the keyptr without keeping the KeyPtr itself around. Remember that the KeyPtr is destroyed when you leave scopes!
  If you do this, it is possible that the Key Manager will think you're done with the object and delete it. Or it might not, if someone else has a KeyPtr to it somewhere. This is another source of hard-to-find bugs.