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  1. //rvalue classes and move function
  2. template <class T>
  3. struct r_ref {
  4.     T& ref;
  5.     r_ref(T& rhs) :ref(rhs) {}
  6.     r_ref(const r_ref& rhs) :ref(rhs.ref) {}
  7. };
  8. template <class T>
  9. struct r_val : r_ref<T> {
  10.     mutable T val;
  11.     r_val(T& rhs) :r_ref<T>(val), val(rhs) {}
  12.     r_val(const r_ref<T>& rhs) :r_ref<T>(val), val(rhs) {}
  13. };
  14. template <class T>
  15. r_ref<T> move(T& rhs) {return r_ref<T>(rhs);}
  16.  
  17.  
  18.  
  19.  
  20.  
  21. //demo classes
  22. #include <iostream>
  23. #include <string>
  24. class demo {
  25. public:
  26.     std::string data;
  27.     demo() : data("LONG STRING SO NO CHEATS") {std::cout<<"default construct ";}
  28.     demo(const demo& rhs) : data(rhs.data.begin(),rhs.data.end()) {std::cout<<"copy construct ";}
  29.     demo(const r_ref<demo>& rhs) : data("MOVED FROM NO CHEATS") {data.swap(rhs.ref.data); std::cout<<"move construct ";}
  30.     demo& operator=(const demo& rhs) {data.assign(rhs.data.begin(),rhs.data.end()); std::cout<<"copy assignment "; return *this;}
  31.     demo& operator=(const r_ref<demo>& rhs) {data.swap(rhs.ref.data); std::cout<<"move assignment "; return *this;}
  32.     ~demo() {std::cout<<"destruct ";}
  33.     void prove() const {std::cout<<(void*)data.c_str()<<' '<<data.c_str();}
  34. };
  35.  
  36. r_val<demo> function(demo rhs) {
  37.     std::cout << "\nwant move assignment: ";
  38.     demo obj(move(rhs));
  39.     std::cout << "\nwant VAR1: ";
  40.     obj.prove();
  41.     std::cout << "\nwant move construct, destruct, destruct, move construct, destruct:\n\t";
  42.     return move(obj);
  43. }
  44.  
  45.  
  46.  
  47. //test suite
  48. int main() {
  49.    std::cout << "\nwant default construct: ";   demo a;
  50.    std::cout << "\nwant VAR1: ";                a.prove();
  51.    std::cout << "\nwant move construct: ";      demo b = function(move(a));   
  52.    std::cout << "\nwant VAR2: ";                a.prove();
  53.    std::cout << "\nwant VAR1: ";                b.prove();
  54.    std::cout << "\nwant copy assignment: ";     a = b;
  55.    std::cout << "\nwant VAR3: ";                a.prove();
  56.    std::cout << "\nwant VAR1: ";                b.prove();
  57.    std::cout << "\nwant move assign: ";         a = move(b);
  58.    std::cout << "\nwant VAR1: ";                a.prove();
  59.    std::cout << "\nwant VAR3: ";                b.prove();
  60.    std::cout << "\nwant 2x destruct: ";
  61. }
  62.  
Success #stdin #stdout 0s 3032KB
comments (?)
stdin
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Standard input is empty
stdout
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want default construct: default construct 
want VAR1: 0x9c18014 LONG STRING SO NO CHEATS
want move construct: move construct 
want move assignment: move construct 
want VAR1: 0x9c18014 LONG STRING SO NO CHEATS
want move construct, destruct, destruct, move construct, destruct:
	move construct destruct move construct destruct destruct 
want VAR2: 0x9c18044 MOVED FROM NO CHEATS
want VAR1: 0x9c18014 LONG STRING SO NO CHEATS
want copy assignment: copy assignment 
want VAR3: 0x9c180bc LONG STRING SO NO CHEATS
want VAR1: 0x9c18014 LONG STRING SO NO CHEATS
want move assign: move assignment 
want VAR1: 0x9c18014 LONG STRING SO NO CHEATS
want VAR3: 0x9c180bc LONG STRING SO NO CHEATS
want 2x destruct: destruct destruct
https://ideone.com/Csitz
language:
C++ (gcc 8.3)
created:
10 years ago
visibility:
secret

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