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POVariadic template loop, non recursive
 

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  1. POVariadic template loop, non recursive
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    <p>I have some function, which performs complex drawings. [in pseudocode]</p> <pre><code>template&lt;typename fields...&gt; // field names of Brush class void someFunction(){ for(very large loop){ Brush brush = getBrush(); int x; foreach(field : fields){ // &lt;--- this somehow should be replaced x = brush.*field; brush.update(x); } } } </code></pre> <p>[listing 1]</p> <p>I call it:</p> <pre><code>someFunction&lt;&amp;Brush::xPos1, &amp;Brush::xPos2, &amp;Brush::xPos3, &amp;Brush::xPos4&gt;() </code></pre> <p>And I want compiler to generate something like this:</p> <pre><code>void someFunction(){ for(very large loop){ Brush brush = getBrush(); int x; x = brush.xPos1; brush.update(x); x = brush.xPos2; brush.update(x); x = brush.xPos3; brush.update(x); x = brush.xPos4; brush.update(x); } } </code></pre> <p>[listing 2]</p> <p>I mean, I want to get rid of that foreach(field : fields).</p> <hr> <p>I found this variadic template loop implementation, but it is recursive. For performance resons this even worst than foreach loop</p> <pre><code>int a; template &lt;class T&gt; void print(const T msg) { a = msg; } // And this is the recursive case: template &lt;class A, class... B&gt; void print(A head, B... tail) { a = head; print(head); print(tail...); } </code></pre> <p>[listing 3]</p> <hr> <p>So the question is.... Is it possible possible to achive result as on [listing 2]? If yes, than how?</p>
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    1. CO`fields` variadic pack is a set of types, you are passing pointers
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    2. COGo and learn about polymorphism instead of using features in a way they are not dessigned for (And have no sense at all).
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    3. COI'd expect the compiler to unroll a 4-iterations loop.
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