// This example shows why typename is needed.
// Don’t confuse typename with typedef.
//
// • What are the requirements of a set? 🦆
// • What are the requirements of a funnyset? 🦆
//
// Make a funnyset of strings.

#include <iostream>
#include <set>

using namespace std;

// funnyset is just like a set, except that it doesn’t like 42.
// This is NOT inheritance--there is no is-a relationship.
// Instead, it’s a has-a relationship, with forwarding methods.

template <class T>
class funnyset {
  public:
    typedef set<T>::iterator iterator;		// This won’t compile.  Why?

    void insert(const T &val) {
	if (val != 42)
	    storage.insert(val);
    }
    iterator begin() const { return storage.begin(); }
    iterator end() const { return storage.end(); }
    size_t size() const { return storage.size(); }
  private:
    set<T> storage;
};

int main() {
    funnyset<double> ss;
    ss.insert(3.14159);
    ss.insert(42.0);
    ss.insert(2.71828);

    for (funnyset<double>::iterator it=ss.begin(); it!=ss.end(); ++it)
    	cout << *it << ' ';
    cout << '\n';

    for (auto d : ss)
    	cout << d << ' ';
    cout << '\n';
}