(C++) Avoid duplication in const and non-const member functions

In good member function design, avoid duplication in const and non-const member functions [1,2]. Instead, have the non-const member function call the const member function.

---

#include <vector> #include <cassert> struct StoreTenInts {   StoreTenInts() : mV(std::vector<int>(10,0)) {}   int& operator[](const int i)   {     //Calls the const version of operator[]     //To avoid duplication in const and non-const member functions [1]     return const_cast<int&>(const_cast<const StoreTenInts&>(*this)[i]);   }   const int& operator[](const int i) const   {     //The actual work of operator[]     assert(i >= 0 && i < 10);     return mV[i];   }   private:   std::vector<int> mV; };

References

• [1] Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 94: 'Avoid casting away const', item 'Exceptions'
• [2] Scott Meyers. Effective C++ (3rd edition). ISBN: 0-321-33487-6. Item 3, paragraph 'Avoid duplication in const and non-const member functions'