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  1. #include <memory>
  2. #include <vector>
  3. #include <iostream>
  4.  
  5. struct some_interface
  6. {
  7.     virtual ~some_interface()
  8.     {}
  9.  
  10.     virtual void foo() = 0;
  11. };
  12.  
  13. template <typename Foo>
  14. struct C : public some_interface
  15. {
  16.     std::unique_ptr<Foo> foo_;
  17.  
  18.     C(std::unique_ptr<Foo> foo_)
  19.         : foo_(std::move(foo_))
  20.     {}
  21.  
  22.     virtual void foo()
  23.     {
  24.         foo_->foo();
  25.     }
  26. };
  27.  
  28. struct known_foo
  29. {
  30.     void foo()
  31.     {
  32.         std::cout << "known foo\n";
  33.     }
  34. };
  35.  
  36. struct foo_base
  37. {
  38.     virtual ~foo_base()
  39.     {}
  40.  
  41.     virtual void foo() = 0;
  42. };
  43.  
  44. struct unknown_foo : public foo_base
  45. {
  46.     virtual void foo()
  47.     {
  48.         std::cout << "unknown foo\n";
  49.     }
  50. };
  51.  
  52. template <typename T, typename... Args>
  53. std::unique_ptr<T> bad_make_unique(Args&&... args)
  54. {
  55.     return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
  56. }
  57.  
  58. int main()
  59. {
  60.     std::vector<std::unique_ptr<some_interface>> interfaces;
  61.     interfaces.push_back(bad_make_unique<C<known_foo>>(bad_make_unique<known_foo>()));
  62.     interfaces.push_back(bad_make_unique<C<foo_base>>(bad_make_unique<unknown_foo>()));
  63.  
  64.     for (auto& e : interfaces)
  65.         e->foo();
  66. }
Success #stdin #stdout 0s 2988KB
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stdin
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Standard input is empty
stdout
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known foo
unknown foo
https://ideone.com/71VWTG
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
secret

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