template<class T>
class Util::Setable< T >
Template for a value that can be set or declared null (i.e., unknown).
Type T must be copy-constructable and have an assignment (=) operator.
Convention for MPI programs: In parallel MPI programs in which a value for a variable is calculated by a reduce operation and is set only on a master processor, a default value should be set on all other processors whenever the true value is set on the master. This indicates on all processors that the value is known, though it may only be available on the master processor. Similarly, when a value is unset, the unset() function should be called on all processors. This convention allows the isSet() function to be used on all processors to query whether the value is known, which may be then be used to decide when to initiate a recomputation that may require computation on all processors. This convention is imposed by the isValid() function, which requires that isSet have the same value on all processors within a communicator (i.e., all true or all false).
Definition at line 38 of file Setable.h.