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POAssign to object being created in c++
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copied!<p>I'm writing some functions to operate on vector data.</p> <p>I defined the objects non-copyable (private copy constructor and assignment operator).</p> <p>Then I defined the templated operator =</p> <pre><code>template <typename G> inline const TMatrix &operator=(const G &gen) { ir_mat::Copy<G, Dimension>::start(m_data, gen); return *this; } </code></pre> <p>and some extra operators, like '+', '*', as described in this <a href="http://www.flipcode.com/archives/Faster_Vector_Math_Using_Templates.shtml" rel="nofollow">article</a>.</p> <p>Now I can assign the result of an expression to an object:</p> <pre><code>Vector3f v1, v2, v3; v1 = v2 + v3; </code></pre> <p>Why can't I declare a variable and assign it in a single statement?</p> <pre><code>Vector3f v1, v2; Vector3f v3 = v1 + v2; </code></pre> <p>Is it because this assignment tries to create a temporary object before instantiating the variable, and then copy it into the new object? Can I use my operator '=' also for instantiating new objects, without temporary storage? Do I have to define a special constructor for that?</p> <p><strong>Update</strong></p> <p>I also defined a templated copy constructor (in its simplest form, probably):</p> <pre><code>template <typename G> TMatrix(const G &data) { operator=(data); } </code></pre> <p>Now I can also instantiate v3 as:</p> <pre><code>Vector3f v3(v1 + v2); </code></pre> <p>But still no luck with the other assignment:</p> <pre><code>Vector3f v3 = v1 + v2; </code></pre>

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