Suppose i've data array 0,0,1,1,2,2,5,5,7,7,2,2 as data member in class and i want to define subscript operator in such they
[i] returns me 2*i element of array but also i want let user to set elements, so
[i] = n, must be applied to both 2*i and 2*i+1.
Is it possible to do it with showing to user only subscript operator?
0,0,1,1,2,2,5,5,7,7,2,2 [3] = 4; 0,0,1,1,2,2,4,4,7,7,2,2 another workarounds? and in general it may be not only two elements.
Indirectly, yes.
You can return a dedicated type with the subscript operator that works basically like a functor and takes care of assigning the value according to your specification:
struct AssignFunctor { MyArrayType& parent; size_t index; AssignFunctor(MyArrayType& parent, size_t index) : parent(parent), index(index) {} AssignFunctor& operator=(int k) { parent.set(index,k); parent.set(index*2,k); } operator int() const { return parent.get(index); } }; struct MyArrayType { AssignFunctor operator[](size_t index) { return AssignFunctor(*this,index); } int operator[](size_t index) const { return get(index); } void set(size_t,int); int get(size_t) const; }; I am pretty sure you can implement it as mentioned above. But there's a ground rule for operator overloading. Don't change the meaning of the operator
In the user's perspective you're setting one element but that is applied to a different one as well. Better give meaningful function or change the design of your data structure.
operator[]). However, you might also simulate your array with a regular array and duplicate the members when they are read (what you should do depends on how you use this custom array).