Using a std::set with a custom comparator + typeid

set.cpp

#include <iostream>

class Poly
{
public:
  virtual std::string name() const = 0;
  virtual ~Poly() = default;
};

class Impl1 : public Poly
{
public:
  std::string name() const override 
  {
    return "I am Impl1";
  }
};

class Impl2 : public Poly
{
public:
  std::string name() const override 
  {
    return "I am Impl2";
  }
};

struct Cmp
{
    bool operator()(const Poly* p1, const Poly* p2) const
    {
        return typeid(*p1).name() < typeid(*p2).name();
    }
};

#include <set>
int main() {
  std::set<Poly*, Cmp> s1;
  s1.insert(new Impl1());
  s1.insert(new Impl2());
  s1.insert(new Impl2()); // (note : memory leak here)
  for (Poly* p : s1)
  {
      std::cout << p->name() << std::endl;
      delete p;
  }
}