RWFileStat
RWFileStat is an abstraction of the state of a file system object and provides that information in a portable manner. Note that RWFileStat type is not assignable, copy constructible, or equality comparable:
// ...
RWFileStat s0 ("somefile.txt");
RWFileStat s1;
s1 = s0; // fail; not Assignable
RWFileStat s2 (s0); // fail; not Copy Constructible
return s0 == s1; // fail; not Comparable
// ....
