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copied!<p>First, i believe you originally mean to return</p> <pre><code>StaticVector<N> </code></pre> <p>Instead of always a specialization with N==3 . So, what you want to do is writing it like this:</p> <pre><code>template <unsigned int N> class StaticVector { public: // because of the injected class-name, we can refer to us using // StaticVector . That is, we don't need to name all template // parameters like StaticVector<N>. static StaticVector create3dVec(double x1, double x2, double x2) { // create a new, empty, StaticVector return StaticVector(); } }; </code></pre> <p>If you really want to always return a 3dVector, you would probably want to restrict it to N==3, so that for example <code>StaticVector<4>::create3dVec</code> doesn't work. You can do that using the technique described <a href="https://stackoverflow.com/questions/347096/how-can-i-get-a-specialized-template-to-use-the-unspecialized-version-of-a-member/347107#347107"><strong>here</strong></a>.</p> <p>If you want to have a function like <code>createVec</code> that works with any size, you probably want to replace the parameters with an array. You can do otherwise, but that's advanced and requires some macro tricks applied with boost::preprocessor. It's not worth it i think. The next C++ version will provide <em>variadic templates</em> for this purpose. Anyway,consider using something like this:</p> <p>I think it would only complicate this unnecessarily here. A quick solution is to use a boost::fusion::vector instead, putting it into the class template instead of the version above:</p> <pre><code>static StaticVector createVec(double (&values)[N]) { // create a new, empty, StaticVector, initializing it // with the given array of N values. return StaticVector(); } </code></pre> <p>You could use it with</p> <pre><code>double values[3] = {1, 2, 3}; StaticVector<3> v = StaticVector<3>::createVec(values); </code></pre> <p>Note that it accepts an array by reference. You can't give it a pointer. That is because it matches the use of parameters: You couldn't provide less or more arguments for the other way too. It will also protect you from cases like this:</p> <pre><code>// oops, values is a null pointer! StaticVector<3> v = StaticVector<3>::createVec(values); </code></pre> <p>An array never can be a null pointer. Of course if you like, you can always change the array parameter to a pointer. It would just be my personal preference :)</p>

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