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  1. #include <boost/optional.hpp>
  2. #include <boost/bind.hpp>
  3. #include <iostream>
  4. #include <ostream>
  5. using namespace std;
  6.  
  7. template<unsigned ID,typename Functor>
  8. boost::optional<Functor> &get_local()
  9. {
  10.     static boost::optional<Functor> local;
  11.     return local;
  12. }
  13.  
  14. template<unsigned ID,typename Functor>
  15. typename Functor::result_type wrapper()
  16. {
  17.     return get_local<ID,Functor>().get()();
  18. }
  19.  
  20. template<typename ReturnType>
  21. struct Func
  22. {
  23.     typedef ReturnType (*type)();
  24. };
  25.  
  26. template<unsigned ID,typename Functor>
  27. typename Func<typename Functor::result_type>::type get_wrapper(Functor f)
  28. {
  29.     (get_local<ID,Functor>()) = f;
  30.     return wrapper<ID,Functor>;
  31. }
  32.  
  33. // ----------------------------------------------------------------------
  34.  
  35. void test(void (*fptr)())
  36. {
  37.     fptr();
  38. }
  39.  
  40. struct SomeStruct
  41. {
  42.     int data;
  43.     void some_method()
  44.     {
  45.         cout << data << endl;
  46.     }
  47.     void another_method()
  48.     {
  49.         cout << -data << endl;
  50.     }
  51. };
  52.  
  53. int main()
  54. {
  55.     SomeStruct local[] = { {11}, {22}, {33} };
  56.  
  57.     test(get_wrapper<0>(  boost::bind(&SomeStruct::some_method,local[0]) ));
  58.     test(get_wrapper<1>(  boost::bind(&SomeStruct::another_method,local[0]) ));
  59.  
  60.     test(get_wrapper<2>(  boost::bind(&SomeStruct::some_method,local[1]) ));
  61.     test(get_wrapper<3>(  boost::bind(&SomeStruct::another_method,local[1]) ));
  62.  
  63.     test(get_wrapper<4>(  boost::bind(&SomeStruct::some_method,local[2]) ));
  64.     test(get_wrapper<5>(  boost::bind(&SomeStruct::another_method,local[2]) ));
  65. }
  66.  
Success #stdin #stdout 0.01s 2728KB
comments (?)
stdin
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Standard input is empty
stdout
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11
-11
22
-22
33
-33
https://ideone.com/6UGfrH
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
secret

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