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    <p>One option you could try (I haven't tested this):</p> <pre><code>template&lt;typename T&gt; class MyRef{ private: int index; Polynom&lt;T&gt;*p; public: MyRef(int index, Polynom&lt;T&gt;*p) : index(index), p(p) { } MyRef&lt;T&gt;&amp; operator=(T const&amp;t); //and define these appropriately T operator T() const; }; </code></pre> <p>and define:</p> <pre><code> MyRef&lt;T&gt; operator[](int index){ return MyRef&lt;T&gt;(index, this); } </code></pre> <p>This way when you assign a value to the "reference" it should have access to all the needed data in the polynomial, and take the appropriate actions.</p> <p>I am not familiar enough with your implementation, so I'll instead give an example of a very simple dynamic array that works as follows:</p> <ul> <li>you can read from any <code>int index</code> without concern; elements not previously written to should read off as <code>0</code>;</li> <li>when you write to an element past the end of the currently allocated array, it is reallocated, and the newly allocated elements are initialized to <code>0</code>.</li> </ul> <pre><code>#include &lt;cstdlib&gt; #include &lt;iostream&gt; using namespace std; template&lt;typename T&gt; class my_array{ private: T* _data; int _size; class my_ref{ private: int index; T*&amp; obj; int&amp;size; public: my_ref(T*&amp; obj, int&amp;size, int index) : index(index), obj(obj), size(size){} my_ref&amp; operator=(T const&amp; t){ if (index&gt;=size){ obj = (T*)realloc(obj, sizeof(T)*(index+1) ); while (size&lt;=index) obj[size++]=0; } obj[index] = t; return *this; } //edit:this one should allow writing, say, v[1]=v[2]=v[3]=4; my_ref&amp; operator=(const my_ref&amp;r){ operator=( (T) r); return *this; } operator T() const{ return (index&gt;=size)?0:obj[index]; } }; public: my_array() : _data(NULL), _size(0) {} my_ref operator[](int index){ return my_ref(_data,_size,index); } int size() const{ return _size; } }; int main(){ my_array&lt;int&gt; v; v[0] = 42; v[1] = 51; v[5] = 5; v[5]=6; v[30] = 18; v[2] = v[1]+v[5]; v[4] = v[8]+v[1048576]+v[5]+1000; cout &lt;&lt; "allocated elements: " &lt;&lt; v.size() &lt;&lt; endl; for (int i=0;i&lt;31;i++) cout &lt;&lt; v[i] &lt;&lt; " " &lt;&lt; endl; return 0; } </code></pre> <p>It's a very simple example and not very efficient in its current form but it should prove the point.</p> <p>Eventually you might want to overload <code>operator&amp;</code> to allow things like <code>*(&amp;v[0] + 5) = 42;</code> to work properly. For this example, you could have that <code>operator&amp;</code> gives a <code>my_pointer</code> which defines <code>operator+</code> to do arithmetic on its <code>index</code> field and return a new <code>my_pointer</code>. Finally, you can overload <code>operator*()</code> to go back to a <code>my_ref</code>.</p>
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    1. COThank you! Could you please also clarify the following: 1. Should I make this class inner & private? 2. Can I return a reference to an instance of a private class?
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    2. COI've updated my example to use a private nested class. It still works (see: http://ideone.com/dRr4D) but I haven't used nested classes too much in the past so I don't know what the best practices are.
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    3. COThis won't cover use cases such as `int &r = v[1]; r = 3;`.
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