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  1. // pimpl template courtesy of Matthieu
  2. template <class T>
  3. class pimpl
  4. {
  5. public:
  6.   /**
  7.    * Types
  8.    */
  9.   typedef const T const_value;
  10.   typedef T* pointer;
  11.   typedef const T* const_pointer;
  12.   typedef T& reference;
  13.   typedef const T& const_reference;
  14.  
  15.   /**
  16.    * Gang of Four
  17.    */
  18.   pimpl() : m_value(new T) {}
  19.   explicit pimpl(const_reference v) : m_value(new T(v)) {}
  20.  
  21.   pimpl(const pimpl& rhs) : m_value(new T(*(rhs.m_value))) {}
  22.  
  23.   pimpl& operator=(const pimpl& rhs)
  24.   {
  25.     pimpl tmp(rhs);
  26.     swap(tmp);
  27.     return *this;
  28.   } // operator=
  29.  
  30.   ~pimpl() { delete m_value; }
  31.  
  32.   void swap(pimpl& rhs)
  33.   {
  34.     pointer temp(rhs.m_value);
  35.     rhs.m_value = m_value;
  36.     m_value = temp;
  37.   } // swap
  38.  
  39.   /**
  40.    * Data access
  41.    */
  42.   pointer get() { return m_value; }
  43.   const_pointer get() const { return m_value; }
  44.  
  45.   reference operator*() { return *m_value; }
  46.   const_reference operator*() const { return *m_value; }
  47.  
  48.   pointer operator->() { return m_value; }
  49.   const_pointer operator->() const { return m_value; }
  50.  
  51. private:
  52.   pointer m_value;
  53. }; // class pimpl<T>
  54.  
  55. // Swap
  56. template <class T>
  57. void swap(pimpl<T>& lhs, pimpl<T>& rhs) { lhs.swap(rhs); }
  58.  
  59. // Test Case
  60. // c.h -------------------
  61. class C {
  62.  
  63. public:
  64.     int getI() const;
  65.     void setI( int i );
  66.  
  67. private:
  68.     struct Private;
  69.     pimpl<Private> d;
  70. };
  71.  
  72. // c.cpp ------------------
  73. struct C::Private {
  74.     int i;
  75. };
  76.  
  77. int C::getI() const {
  78.     return d->i;
  79. }
  80.  
  81. void C::setI( int i ) {
  82.     d->i = i;
  83. }
  84.  
  85. #include <iostream>
  86. int main()
  87. {
  88.     C a;
  89.     a.setI( 4 );
  90.     C b = a;
  91.     b.setI( 5 );
  92.  
  93.     std::cout << a.getI() << b.getI() << std::endl;
  94. }
  95.  
Success #stdin #stdout 0.02s 2812KB
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https://ideone.com/rgFi0
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
public

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