Consider the following code:
class Base
{
public:
virtual ~Base() = 0 {};
virtual double get() = 0;
};
class D1 : public Base
{
public:
D1(double n) : val_(n) {}
double get() const { return val_; }
private:
double val_;
};
class D2 : public Base
{
D2(double n) : val_(n) {}
double get() const { return val_; }
private:
double val_;
};
bool operator < (const Base& left, const Base& right)
{
return (left.get() < right.get());
}
I can create a ptr_set of Base like this:
boost::ptr_set<Base> set;
But I can't create a ptr_map with Base as key, like this:
boost::ptr_map