On 5/27/11 7:02 AM, Krzysztof Czainski wrote:
I had prepared such a class some time ego, and I've been using it for a while now. Is there interest in adding it to boost? Perhaps as part of the operators library?
Hmm, I like the idea of insulating the user from having to construct a fancy type to return a safe bool, but it is a little weird to have the user implement the ! operator instead of the bool operator directly. How about simply defining an as_bool method and having the user implement that: template< class Derived, class Base = empty_t> class boolable : public Base { void unspecified_bool_t_f() {} typedef void (boolable::*unspecified_bool_t)(); public: operator unspecified_bool_t() const { return static_cast<Derived const&>( *this ).as_bool() ?&boolable::unspecified_bool_t_f : 0; } bool operator!() const { return !(*this); } }; Usage: struct X : public boolable<X> { bool as_bool() const { return condition; } };