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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. class VisualizableVector {
  5.   public:
  6.     class proxy {
  7.       public:
  8.         proxy (std::vector<int> *v) : vect (v) {
  9.             std::cout << "Before size is: " << vect->size() << std::endl;
  10.         }
  11.         std::vector<int> * operator -> () { return vect; }
  12.         std::vector<int> & operator * () { return *vect; }
  13.         ~proxy () { std::cout << "After size is: " << vect->size() << std::endl; }
  14.       private:
  15.         std::vector <int> * vect;
  16.     };        
  17.     VisualizableVector (std::vector<int> *v) : vect(v) {}            
  18.     ~VisualizableVector () { delete vect; }   
  19.     proxy operator -> () { return proxy (vect); }
  20.     proxy operator * () { return proxy (vect); }
  21.   private:
  22.     std::vector <int> * vect;
  23. };
  24.  
  25. int main()
  26. {
  27.   VisualizableVector vecc (new std::vector<int>);
  28.  
  29. 	vecc->push_back(30);      		// ok		// one ->
  30.   //vecc.operator->().push_back(30);// error	// one ->
  31.  
  32.   //vecc->->push_back(30);      	// error	// two ->
  33.   vecc.operator->()->push_back(30);	// ok		// two ->
  34.  
  35.   auto proxy3 = vecc.operator->();		// 1st operator->()
  36.   auto pointer = proxy3.operator->();	// 2nd operator->()
  37.   pointer->push_back(30);				// 3rd operator->()
  38.  
  39.   return 0;
  40. }
Success #stdin #stdout 0s 3416KB
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stdin
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Standard input is empty
stdout
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Before size is: 0
After size is: 1
Before size is: 1
After size is: 2
Before size is: 2
After size is: 3
https://ideone.com/89kfYF
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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