gistfile1.txt

#include <iostream>
#include <memory>

using namespace std;

static int mycount = 0;

class SomeObject {
private:

public:
  int value;
  int ncpy;

  SomeObject() {
    value = mycount++;
    ncpy = 0;
    cout << "  Created " << *this << endl;
  }
  SomeObject(const SomeObject& that) {
    this->value = that.value;
    this->ncpy  = that.ncpy+1;
    cout << "  Making " << *this << endl;
  }
  ~SomeObject() {
    cout << "  Destroying " << *this << endl;
  }
  friend ostream& operator<<(ostream& str, const SomeObject& obj);
};

ostream& operator<<(ostream& str, const SomeObject& obj) {
  if(obj.ncpy > 0) {
    str << "copy " << obj.ncpy << " of ";
  }
  str << "SomeObject(" << obj.value << ")";
  return str;
}

void byref(SomeObject& obj) { cout << "  Received: " << obj << endl; }
void byptr(SomeObject* obj) { cout << "  Received: " << *obj << endl; }
void byval(SomeObject obj)  { cout << "  Received: " << obj << endl; }

unique_ptr<SomeObject> createuqptr() { return unique_ptr<SomeObject>(new SomeObject()); }
SomeObject* createbyptr() { return new SomeObject(); }
SomeObject  createbyval() { return SomeObject(); }

void testcreates() {

  cout << "Returning a reference" << endl;
  auto obj1 = createuqptr();

  cout << "Returning a pointer" << endl;
  SomeObject* obj3 = createbyptr();
  delete obj3;

  cout << "Returning a value" << endl;
  SomeObject obj4 = createbyval();

  cout << "End of create tests" << endl;
}

void testcalls() {
  SomeObject obj;

  cout << "Calling with reference, this should NOT copy" << endl;
  byref(obj);

  cout << "Calling with pointer, this should NOT copy" << endl;
  byptr(&obj);

  cout << "Calling by value, this should copy" << endl;
  byval(obj);

  cout << "Doing some & assignments" << endl;
  SomeObject& a = obj;
  SomeObject& b = a;

  cout << "Doing some value assignments" << endl;
  SomeObject c = obj;
  SomeObject d = c;

  cout << "auto from reference" << endl; {
    SomeObject& refToObj = obj;
    auto cpy = refToObj;
  }

  cout << "auto& from reference" << endl; {
    SomeObject& refToObj = obj;
    auto& cpy = refToObj;
  }

  /*
  cout << "NotCopyable auto from reference" << endl; {
    NotCopyable obj2;
    obj2.value = 43;
    NotCopyable& refToObj2 = obj2;
    auto cpy = refToObj2;
  }
  */

  cout << "End of call tests" << endl;
}

int main(int argc, char * argv[]) {
  cout << "========================= TESTING CALLS =========================" << endl;
  testcalls();
  cout << "======================== TESTING CREATES ========================" << endl;
  testcreates();
}