#include <iostream>
#include <string>
#include <map>
#include <functional>
 
using namespace std;
 
struct BaseClass {virtual void foo()=0;};
struct DerivedClass1 : public BaseClass {void foo() {cout << "1" << endl;}};
struct DerivedClass2 : public BaseClass {void foo() {cout << "2" << endl;}};
 
map<string,function<BaseClass*()> > factory {
    {"one", [](){return new DerivedClass1();}}
,   {"two", [](){return new DerivedClass2();}}
};
 
int main() {
    BaseClass *a = factory["one"]();
    BaseClass *b = factory["two"]();
    a->foo();
    b->foo();
    delete a;
    delete b;
	return 0;
}

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