ranges/tracedcoll.hpp

The following code example is taken from the book
C++23 - The Complete Guide by Nicolai M. Josuttis, Leanpub, 2026
The code is licensed under a Creative Commons Attribution 4.0 International License.

---

// raw code

#ifndef TRACEDCOLL_HPP
#define TRACEDCOLL_HPP

#include <iostream>
#include <vector>
#include <print>

template<typename ValT>
class TracedColl {
private:
  std::vector<ValT> values;
public:
  TracedColl ()
   : values{} {
      std::println("** CONSTRUCT {}", values);
  }
  TracedColl (const auto&... vals)
   : values{vals...} {
      std::println("** CONSTRUCT {}", values);
  }
  friend std::ostream& operator<< (std::ostream& os, const TracedColl& c) {
    std::println(os, "{}\n", c.values);
    return os;
  }

  auto begin() { return values.begin(); }
  auto begin() const { return values.begin(); }
  auto end() { return values.end(); }
  auto end() const { return values.end(); }

  // tracing copy/move and destructor:
  TracedColl(const TracedColl& c)
   : values{c.values} {
    std::println("** COPY-CONSTRUCT {}", values);
  }
  TracedColl(TracedColl&& c)
   : values{std::move(c.values)} {
    std::println("** MOVE-CONSTRUCT {}", values);
  }
  TracedColl& operator=(const TracedColl& c) {
    std::println("** COPY-ASSIGN {} to {}", c.values, values);
    values = c.values;
  }
  TracedColl& operator=(TracedColl&& c) {
    std::println("** MOVE-ASSIGN {} to {}", c.values, values);
    values = std::move(c.values);
  }
  ~TracedColl() {  // tracing destructor
    std::println("** DESTRUCT {}", values);
  }
};

#endif // TRACEDCOLL_HPP