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  1. #include <functional>
  2.  
  3. template <typename T>
  4. const T& default_get(T& value)
  5. { return value; }
  6.  
  7. template <typename T>
  8. const T& default_set(T& value, const T& rhs)
  9. { return value = rhs; }
  10.  
  11. template <typename T,
  12.           std::function<const T& (T&)> get = default_get<T>,
  13.           std::function<T& (T&, const T&)> set = default_set<T>>
  14. class property
  15. {
  16. public:
  17.     operator const T& () const
  18.     { return get(_value); }
  19.  
  20.     T& operator= (const T& rhs)
  21.     { return set(_value, rhs); }
  22.  
  23. private:
  24.     T _value;
  25. };
  26.  
  27. const int& log(const int& value) { std::cout << value; return value;  }
  28.  
  29. struct S
  30. {
  31.     property<int,
  32.         // log() used as decorator-style logging wrapper in properties
  33.         [] (int& value) { log(default_get<int>(value)); },
  34.         [] (int& value, const int& rhs) { log(default_set<int>(value, rhs)); }>
  35.             field_name;
  36. };
  37.  
  38. /*
  39.  * The following is already possible with plain old functions, but cumbersome to write.
  40.  */
  41.  
  42. template <typename T,
  43.           const T& (*get)(const T&) = default_get<T>,
  44.           T& (*set)(T&, const T&) = default_set<T> >
  45. class property
  46. {
  47. public:
  48.     operator const T& () const
  49.     { return get(_value); }
  50.  
  51.     T& operator= (const T& rhs)
  52.     { return set(_value, rhs); }
  53.  
  54. private:
  55.     T _value;
  56. };
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https://ideone.com/jrQzs
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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