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  1. #include <stdio.h>
  2.  
  3. //////////////////////////////////////////////
  4. // Specific case
  5. //////////////////////////////////////////////
  6. class CPassive
  7. {
  8. public:
  9.     CPassive()
  10.     {
  11.         printf(" passively called ");
  12.     }
  13. };
  14.  
  15. class CActive
  16. {
  17. private:
  18.     static CPassive ms_passive;
  19. };
  20. CPassive CActive::ms_passive;
  21. ///////////////////////////////////////////////////////////
  22. // GENERIC TYPES
  23. ///////////////////////////////////////////////////////////
  24. class CSample
  25. {
  26. public:
  27.     CSample()
  28.     {
  29.         printf("sample ");
  30.     }
  31. };
  32.  
  33. template <typename T>
  34. class CGenericPassive
  35. {
  36. public:
  37.     CGenericPassive()
  38.     {
  39.         T sample;
  40.         printf(" generic passive .. ");
  41.     }
  42. private:
  43. };
  44.  
  45. template <typename T>
  46. class CGenericActive
  47. {
  48. private:
  49.     static CGenericPassive<T> ms_passive;
  50. public:
  51.     CGenericActive()
  52.     {
  53.       // just reference it so it gets instantiated
  54.       (void)ms_passive;
  55.     }
  56.  
  57. };
  58. template<typename T>
  59. CGenericPassive<T> CGenericActive<T>::ms_passive;
  60.  
  61. int main(int argc, char** argv)
  62. {
  63.     CActive activeExample; // instantiates the static member
  64.     CGenericActive<CSample> activeExample2; // instantiated now
  65. }
Success #stdin #stdout 0s 3296KB
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 passively called sample  generic passive ..
https://ideone.com/Y31PJA
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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