fork(2) download
copy 
  1.  
  2. #include <iostream>
  3. #include <string>
  4.  
  5. using namespace std;
  6.  
  7. struct cache {
  8.     bool valid;
  9.     string rep;
  10. };
  11.  
  12. class Date {
  13. public:
  14.     Date(int dd, int mm, int yy) : d{dd}, m{mm}, y{yy}, c{new cache{false, ""}} {};
  15.     ~Date() { delete c; }
  16.     string string_rep() const;
  17. private:
  18.     int d,  m, y;
  19.     cache * c;
  20.     void compute_cache_value() const;
  21. };
  22.  
  23. string Date::string_rep() const {
  24.     if (!c->valid) {
  25.         compute_cache_value();
  26.         c->valid = true;
  27.     }
  28.     return c->rep;
  29. }
  30.  
  31. void Date::compute_cache_value() const {
  32.     c->rep = "Hello";
  33. }
  34.  
  35. int main() {
  36.     Date const d(1, 1, 1970);
  37.     cout << d.string_rep();
  38.     return 0;
  39. }
Success #stdin #stdout 0s 3428KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
Hello
https://ideone.com/mTYBVb
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!