...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
A read handler must meet the requirements for a handler.
A value h
of a read handler
class should work correctly in the expression h(ec,
s)
,
where ec
is an lvalue of
type const error_code
and s
is an lvalue of type
const size_t
.