operator_bool.h
// This header intentionally has no include guards.
//
// Copyright (c) 2001-2009 Peter Dimov
//
// Distributed under the Boost Software License, Version 1.0.
// See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt
typedef T * this_type::*unspecified_bool_type;
operator unspecified_bool_type() const // never throws
{
return px == 0? 0: &this_type::px;
}
// operator! is redundant, but some compilers need it
bool operator! () const // never throws
{
return px == 0;
}