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  1. #include <iostream>
  2.  
  3. template <typename T>
  4. class global_ptr
  5. {
  6. public:
  7.     T* get()
  8.     {
  9.         return &get_instance();
  10.     }
  11.  
  12.     T* operator->()
  13.     {
  14.         return get();
  15.     }
  16.  
  17.     T& operator*()
  18.     {
  19.         return *get();
  20.     }
  21.  
  22.     // could add const overloads, so clients can 
  23.     // differentiate between read-only and read/write 
  24.     // access, for smarter mutex locking (shared)
  25.  
  26. private:
  27.     static T& get_instance()
  28.     {
  29.         static T result;
  30.         return result;
  31.     }
  32. };
  33.  
  34. typedef global_ptr<int> global_int;
  35.  
  36. void foo()
  37. {
  38.     // all instances of this actually refer to the same global object
  39.     global_int gi;
  40.     *gi = 5;
  41.  
  42.     std::cout << *gi << std::endl;
  43. }
  44.  
  45. void bar()
  46. {
  47.     global_int gi;
  48.     *gi = 7;
  49.  
  50.     std::cout << *gi << std::endl;
  51. }
  52.  
  53. int main()
  54. {
  55.     // not created until first use
  56.     foo();
  57.     bar();
  58.  
  59.     global_int gi;
  60.     *gi = 11;
  61.  
  62.     std::cout << *gi << std::endl;
  63. }
  64.  
  65. // could be extended, now, to support destruction policies, etc.
Success #stdin #stdout 0s 2828KB
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5
7
11
https://ideone.com/sejqW
language:
C++14 (gcc 8.3)
created:
13 years ago
visibility:
public

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