Arno Schödl wrote:
I just started using boost::optional, and this proved to be generically useful, but I believe is currently not in boost::optional:
template< class T, class Tcompatible > bool optional_assign( T& t, boost::optional<Tcompatible> const& optt) { if( optt ) { t=*optt; return true; } else { return false; } }
so you can write
boost::optional< TMyValue > TryToGetT(); T t;
if( !optional_assign( t, TryToGetT () ) { ... other way to get t ... }
Are you sure you want to do a copy-assignment of your T? Your example would typically be more efficient when doing a move-assignment or a swap instead. What would you think of an optional<T>::swap_if_initialized member function, so that you can do: if( ! TryToGetT().swap_if_initialized(t) { ... other way to get t ... } Implemented as: bool swap_if_initialized(T& arg) { if ( *this ) { // Using the Boost Swap utility: boost::swap(**this, arg); return true; } return false; } Kind regards, Niels -- Niels Dekker http://www.xs4all.nl/~nd/dekkerware Scientific programmer at LKEB, Leiden University Medical Center