c++ - How to index all the derived components in a base component list in Entity -

i trying entity component system design simulation. here confuses me now. trying make entity class

entity.h class entity { public:     entity();     virtual ~entity() = 0;     //---------------------methods---------------------//     void addcomponent(const shared_ptr<component> component);      template<class t>     t* getcomponent() const;      //---------------------members---------------------//     vector<shared_ptr<component>>   m_components; }  entity.cpp template<typename t> t* entity::getcomponent() const {     component::component_type_t typeindex = /*t::component_type*/     t* returnptr = dynamic_pointer_cast<t>(m_components[component_type].get());     return returnptr; } 

and component class looks this

class component { public:     component();     virtual ~component() = 0;     //---------------------methods---------------------//      //---------------------members---------------------//     typedef enum component_type_t     {         mesh_t,         rigidbody_t,         transform_t,         num_types     };     component_type_t componenttype; }; 

they way want use getcomponent() same in unity3d

transform* t = getcomponent<transform>() 

but can see cannot find way yet. way used was

class entity {     .....     component* getcomponent(component::component_type_t componenttype) const     {       return m_components[component_type].get()     }; } 

and use as

transform* t = dynamic_pointer_cast<transform>(getcomponent(component::component_type_t::transform_t)); 

clearly tedious.

so question can use form this?

class entity {     .....     template<class t>     t* getcomponent() const     {     component::component_type_t typeindex = /*t::component_type*/     t* returnptr = dynamic_pointer_cast<t>(m_components[component_type].get());     return returnptr;     }; } 

i feel cleanness , speed keep using std::vector<> storing component pointers, valid design?

did similar long time ago. think doing hard way. can modify code below suit need. components inherited. can remove inheritance , replace class inside class or component classes inside component class.

#include <iostream>  struct vector3 {     float x, y, z;     vector3(float x, float y){}     vector3(float x, float y,float z){} };  template <class t> class component { public:     t t;     void adnewcomponent(){      } };  class mesh{ public:     mesh(){} };  class rigidbody{ public:     rigidbody(){}     void addforce(float x,float y, float z){}     void addforce(vector3 force){} };   class transform{ public:     transform(){} };  class object{  };  class gameobject:object,     component<mesh>,     component<rigidbody>,     component<transform> { public:      template <class t>      t &getcomponent()     {         return this->component<t>::t;     }       template <class t>      t &addcomponent(){          this->component<t>::adnewcomponent();          return this->component<t>::t;      } };   int _tmain(int argc, _tchar* argv[]) {      gameobject gameobject;     gameobject.addcomponent<rigidbody>();     rigidbody rigidbody = gameobject.getcomponent<rigidbody>();     rigidbody.addforce(9,0,0);      std::cin.get();     return 0; }