Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Convert the specified executor to the inner executor type, then use that to construct the adapted executor.
template<
typename OtherExecutor>
executor_with_default(
const OtherExecutor & ex,
typename enable_if< is_convertible< OtherExecutor, InnerExecutor >::value >::type * = 0);