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  1. #include <cstdio>
  2.  
  3. struct A
  4. {
  5.     A()
  6.     :
  7.     dummy(printf("Starting to construct A()\n"))
  8.     {
  9.     	printf("Fully constructed A()\n");
  10.     }
  11.     int dummy;
  12. };
  13.  
  14. template <typename T>
  15. struct Nesting;
  16.  
  17. template <>
  18. struct Nesting<int>
  19. {
  20. 	constexpr static int value = 0;
  21. };
  22.  
  23. template <template <typename> class T, typename I>
  24. struct Nesting<T<I>>
  25. {
  26. 		constexpr static int value = 1 + Nesting<I>::value;
  27. };
  28.  
  29. template<typename T>
  30. struct B
  31. {
  32.     int dummy;
  33.     A a;
  34.     T b;
  35.     B()
  36.     :
  37.     dummy(printf("Starting to construct B() with nesting %d\n", Nesting<B<T>>::value)),
  38.     a(),
  39.     b()
  40.     {
  41.     	printf("Fully constructed B() with nesting %d\n", Nesting<B<T>>::value);
  42.     }
  43. };
  44.  
  45. int main()
  46. {
  47.     B<B<B<int>>> Test;
  48.     return 0;
  49. }
Success #stdin #stdout 0s 3096KB
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stdin
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Standard input is empty
stdout
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Starting to construct B() with nesting 3
Starting to construct A()
Fully constructed A()
Starting to construct B() with nesting 2
Starting to construct A()
Fully constructed A()
Starting to construct B() with nesting 1
Starting to construct A()
Fully constructed A()
Fully constructed B() with nesting 1
Fully constructed B() with nesting 2
Fully constructed B() with nesting 3
https://ideone.com/KylQQb
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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