Auto return type of a function in c++ -

i have problem im not able solve. have tried find similar question here, didnt find working solution me.

my structure is:

class base {     unsigned int id; };  class position: public base {     float x,y;      position(float a, float b): x(a), y(b) {} }  class mass: public base {     float mass;      mass(float a): mass(a) {} } 

i store pointers attributes in map accesed strings. have function, can return attribute list using names. structure , desired functionality should this:

std::map<string, base*> attributes;  ???? getatt(string name) {     return attributes[name]; }  position pos(1,2); mass mass(25.6); attributes.emplace("test_position", &pos); attributes.emplace("test_mass") &mass);  cout << "mass of object " <<getatt("test_mass").mass << endl; cout << "x - position of object " << getatt("test_position").x ;  prints:  mass of object 25.6          x - position of object 1 

this function, addition of attributes , memory managment should encapsuled in class, think wont such problem after thing solved. there way that? thinking templates, dont understand them enough make them work :( thinking not storing attributes in 1 array, way easy. suggestions :)

your getatt return base*, this:

base* getatt(const string& name) { ... } 

but base class doesn't provide interface derived class, can't

getatt("test_mass").mass 

instead have this:

dynamic_cast<mass*>(getatt("test_mass"))->mass; dynamic_cast<position*>(getatt("test_position"))->x; 

there alternatives, example can use tagged union, might complex problem.

by way, [] operator of map create element if doesn't exist, need check getatt isn't returning nullptr.