模仿boost::any类型

#include <iostream>#include <typeinfo>#include <map>#include <string>using namespace std;class IMeta{public:virtual ~IMeta() {}virtual IMeta* clone() = 0;virtual const std::type_info & type() const = 0;virtual ostream& operator<<(ostream& os) = 0;};template <typename T>class metadata : public IMeta{public:T _data;metadata(const T& t){_data = t;}IMeta* clone(){return new metadata(_data);}const std::type_info & type() const{return typeid(_data);}~metadata(){}ostream& operator<<(ostream& os){os << _data;return os;}};class any{friend ostream& operator<<(ostream& os, const any& any_obj);public:IMeta* _meta;template<typename T>any(const T& t) :_meta( new metadata<T>(t) ){}any() : _meta(NULL){}template<typename T>any& operator=(const T& t){delete _meta;_meta = new metadata<T>(t);return *this;}any& operator=(const any& a){if (&a == this)return *this;this->_meta = a._meta->clone();return *this;}const std::type_info& type() const{return _meta ? _meta->type() : typeid(void);}~any(){delete _meta;}};template<typename T>T& any_cast(const any& any_obj){metadata<T> *pmeta = (metadata<T>*)any_obj._meta;return pmeta->_data;}ostream& operator<<(ostream& os, const any& any_obj){os << any_obj._meta;return os;}int _tmain(int argc, _TCHAR* argv[]){map<string, any> people;people["age"] = 3;people["name"] = string("bright");cout << people["age"] << endl;cout << any_cast<string>(people["name"]) << endl;cout << people["name"].type().name() << endl;// map<string, object> people;// people["age"] = meta<int>(3);// people["name"] = meta<string>("bright");// cout << static_cast<meta<int> >(people["name"]) << endl;return 0;}

 

下一步是让它能