Maksym Motornyy wrote: Is there a way to integrate a solution to this problem : [google groups] http://tinyurl.com/dtnx3 -seb
Hello, all.
I want to propose typesafe enums. Sources are available in Boost Sandbox (typesafe_enums.zip). Were tested under VC 7.1.
Main features are: - type safety; - meaningful printable names; - ability to use in switch-case constructs; - iteration through enumerators; - enumerator-specific methods;
Basic usage ===========
class season_policy: public boost::simple_enumeration_policy { public: BOOST_DEFINE_ENUMERATOR( WINTER ) BOOST_DEFINE_ENUMERATOR( SPRING ) BOOST_DEFINE_ENUMERATOR( SUMMER ) BOOST_DEFINE_ENUMERATOR( AUTUMN )
typedef boost::mpl::vector< WINTER, SPRING, SUMMER, AUTUMN > enumerators; };
typedef boost::enumeration< season_policy > season;
Type safety -----------
season s = season::WINTER();
if ( s ) // accidentally forgotten comparison, wouldn't compile BOOST_ASSERT( false );
if ( s == season::SUMMER() ) std::cout << "Let's go in for fishing!";
Meaningful printable names --------------------------
season s = season::WINTER(); BOOST_CHECK_EQUAL( s->get_name(), "WINTER" );
Ability to use in switch-case constructs ----------------------------------------
season s = season::SUMMER();
switch ( s.get_id() ) { case BOOST_ENUMERATOR_ID( season, SUMMER ): break; default: BOOST_ERROR( "Should not fall here." ); break; }
Iteration through enumerators -----------------------------
for ( season::iterator i = season::begin(); i != season::end(); ++i ) std::cout << ( *i )->get_name() << " ";
Advanced usage ==============
class operation_policy { public: class base_enumerator { public: virtual double eval( double operand1, double operand2 ) const = 0; };
template < typename Functor > class enumerator_impl: public base_enumerator { public: double eval( double operand1, double operand2 ) const { return Functor()( operand1, operand2 ); } };
class PLUS: public enumerator_impl< std::plus< double > > { };
class MINUS: public enumerator_impl< std::minus< double > > { };
class TIMES: public enumerator_impl< std::multiplies< double > > { };
class DIVIDE: public enumerator_impl< std::divides< double > > { };
typedef boost::mpl::vector< PLUS, MINUS, TIMES, DIVIDE > enumerators; };
typedef boost::enumeration< operation_policy > operation;
Enumerator-specific methods ---------------------------
for ( season::iterator i = season::begin(); i != season::end(); ++i ) std::cout << ( *i )->eval( 4, 2 ) << " "; // expected output is: 6 2 8 2
Is anybody found it useful?
Sincerely, Maksym Motornyy.
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