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  1. #include <iostream>
  2. #include <vector>
  3. using std::cout;
  4. using std::endl;
  5. using std::vector;
  6.  
  7. class BaseItem{
  8. public:
  9.     virtual BaseItem* clone()
  10.     {
  11.         return new BaseItem(*this);
  12.     }
  13.     virtual void sayHello()
  14.     {
  15.         cout<<"Hello, I am class BaseItem!"<<endl;
  16.     }
  17.     virtual ~BaseItem() {}
  18. };
  19.  
  20. class ChildItem:public BaseItem{
  21. public:
  22.     ChildItem* clone()
  23.     {
  24.         return new ChildItem(*this);
  25.     }
  26.     void sayHello(){
  27.         cout<<"Hello, I am class ChildItem!"<<endl;
  28.     }
  29. };
  30.  
  31.  
  32. template <typename T>
  33. class Handle
  34. {
  35. public:
  36.     Handle():baseItem(NULL), refCount(new size_t(0)) {}
  37.     Handle(T& object):baseItem(object.clone()), refCount(new size_t(1)) {}
  38.  
  39.     Handle(const Handle<T>& other):baseItem(other.baseItem), refCount(other.refCount) { ++*refCount; }
  40.  
  41.     Handle& operator= (const Handle<T>& other)
  42.     {
  43.         ++*other.refCount;
  44.         dec_count();
  45.         baseItem = other.baseItem;
  46.         refCount = other.refCount;
  47.         return *this;
  48.     }
  49.  
  50.     const T* operator->() const {return baseItem;};
  51.     const T& operator*() const {return *baseItem;};
  52.  
  53.     T* operator->() {return baseItem;};
  54.     T& operator*() {return *baseItem;};
  55.  
  56.     virtual ~Handle(void)
  57.     {
  58.         dec_count();
  59.     }
  60. private:
  61.     T *baseItem;
  62.     std::size_t* refCount;
  63.     void dec_count()
  64.     {
  65.         if (-- *refCount == 0 && baseItem != NULL)
  66.         {
  67.             delete baseItem;
  68.             delete refCount;
  69.         }
  70.     }
  71. };
  72.  
  73. int main()
  74. {
  75.     BaseItem item1;
  76.     ChildItem item2;
  77.  
  78.     vector<Handle<BaseItem> > vec;
  79.     vec.push_back(Handle<BaseItem>(item1));
  80.     vec.push_back(Handle<BaseItem>(item2));
  81.  
  82.     for (vector<Handle<BaseItem> >::iterator iter = vec.begin();
  83.       iter != vec.end(); iter++)
  84.     {
  85.       (*(*iter)).sayHello();
  86.     }
  87.     return 0;
  88. }
Success #stdin #stdout 0s 3476KB
comments (?)
stdin
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Standard input is empty
stdout
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Hello, I am class BaseItem!
Hello, I am class ChildItem!
https://ideone.com/DB7L9p
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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