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copied!<p>The <code>to_...</code> member functions all take an argument solely for the purpose of assisting with template argument deduction, so yes, passing a value-initialized<sup>†</sup> instance of the same type you want as the return type is safe, though needlessly inefficient.</p> <p>However, the <code>to_...</code> member functions only exist to assist broken compilers that don't properly support templated conversion operators -- why are you using them in the first place? The clean syntax would be simply:</p> <pre><code>boost::array<int, 3> OneTwoThree() { return boost::assign::list_of(1)(2)(3); } </code></pre> <p>Note that I've used <code>boost::array<></code> here rather than <code>std::tr1::array<></code>; the reason is that the Boost.Assign library has no knowledge (yet) of TR1/C++11 standard libraries, and thus is not properly specialized for <code>std::array<></code> or <code>std::tr1::array<></code>. To add this specialization yourself, and consequently make the above code work with <code>std::tr1::array<></code>, add the following code <strong>after</strong> including the Boost.Assign headers:</p> <pre><code>namespace boost { namespace assign_detail { template<typename T, std::size_t sz> type_traits::yes_type assign_is_array(std::tr1::array<T, sz> const*); }} </code></pre> <p>(Note: only tested with Boost 1.48; earlier versions may need a different specialization.)</p> <hr> <p><sup>†</sup> The syntax in your question is not default-construction, it's value-initialization.</p>

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