Language: C C++ D Haskell Lua OCaml PHP Perl Plain Text Python Ruby Scheme Tcl #include "connectiondb.h" ConnectionDb::ConnectionDb(){ connection.connect("localhost"); std::cout<<"Connection to Database start..."<<std::endl; } ConnectionDb::~ConnectionDb(){ std::cout<<"Close Database"<<std::endl; } void ConnectionDb::connectDb(){ } //create connection ConnectionDb *ConnectionDb::instance_ = 0; //interitance to ControlOne class ConnectByControlOne : public ConnectionDb { public: void connectDb(){ std::cout<<"Connection...."<<std::endl; } }; //create instance ConnectionDb &ConnectionDb::instance(){ if( !instance_ ){ instance_ = new ConnectByControlOne; return *instance_; } } class DisConnection{ public: ~DisConnection(){ delete ConnectionDb::instance_; } }; namespace{ DisConnection d; } Private [?] Run code