demo use of unique pointer

test_unique_ptr.cpp

#include <iostream>
#include <vector>
#include <memory>
using namespace std;

struct dummy_t {
  dummy_t(){}
  dummy_t(int v):val(v){
    cout << "dummy " << val << " constructred." << endl;
  }
  ~dummy_t(){
    cout << "dummy " << val << " destructred." << endl;
  }
  int val;
};

vector<unique_ptr<dummy_t>> gen(int n) {
  vector<unique_ptr<dummy_t>> v;
  for(int i=0;i<n;++i){
    v.emplace_back(unique_ptr<dummy_t>(new dummy_t(i)));
  }
  return v;
}

void g(const dummy_t* d) {
  cout << "g: " << d->val << endl;
}

void gv(const vector<dummy_t*> &v) {
  for(auto& x:v) {
    g(x);
  }
}

void f() {
  cout << "calling f..." << endl;
  auto v = gen(10);
  for(auto& x : v) {
    cout << x->val << endl;
  }

  vector<dummy_t*> vp;
  for(auto& x : v) {
    vp.push_back(x.get());
  }

  gv(vp);
  cout << "leaving f..." << endl;
}

int main() {
  cout << "main begin." << endl;
  f();
  cout << "main end." << endl;
  return 0;
}