Constructors
warning registerAsObserver is left as a backdoor
in case the programmer cannot guarantee that the
object pointed to will remain alive for the whole
lifetime of the handle---namely, it should be set
to false when the passed shared pointer
does not own the pointee (this should only happen
in a controlled environment, so that the
programmer is aware of it). Failure to do so can
very likely result in a program crash. If the
programmer does want the handle to register as
observer of such a shared pointer, it is his
responsibility to ensure that the handle gets
destroyed before the pointed object does.
dereferencing
checks if the contained shared pointer points to anything
allows registration as observable
Shared handle to an observable
All copies of an instance of this class refer to the same observable by means of a relinkable smart pointer. When such pointer is relinked to another observable, the change will be propagated to all the copies.
Class T must inherit from Observable