Wzorzec projektowy strategia - strategy

#include <iostream> #include <vector> #include <string> class iNumeric{ public: virtual void write(const std::vector<std::string> &list) = 0; }; class Numeric : public iNumeric { virtual void write(const std::vector<std::string> &list) { for(int i = 0; i < list.size(); i++){ std::cout << (i + 1) << ") " << list[i] << std::endl; } } }; class Alphabetic : public iNumeric { virtual void write(const std::vector<std::string> &list) { for(int i = 0; i < list.size(); i++){ std::cout << char(i + 97) << ") " << list[i] << std::endl; } } }; class NumericList{ public: enum list_type{ numeric, alphabetic }; protected: std::vector<std::string> list; iNumeric* system; public: NumericList() : system(NULL) {} void setSystem(list_type listType){ if(system) delete system; switch((int)listType){ case list_type::numeric: system = new Numeric; break; case list_type::alphabetic: system = new Alphabetic; break; } } void write(){ if(system){ system->write(list); } } NumericList& operator +=(const std::string &text){ list.push_back(text); return *this; } }; int main(){ NumericList numericlist; numericlist += "Some text line one"; numericlist += "Some text line two"; numericlist.setSystem(NumericList::list_type::numeric); numericlist.write(); numericlist.setSystem(NumericList::list_type::alphabetic); numericlist.write(); std::cin.get(); return 0; }