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    <p>Be very leery of the copy/swap assignment idiom. It can be sub-optimal, especially when applied without careful analysis. Even if you need strong exception safety for the assignment operator, that functionality can be otherwise obtained.</p> <p>For your example I recommend:</p> <pre><code>struct my_type { my_type(std::string name_) : name(std::move(name_)) {} void swap(my_type &amp;other) { name.swap(other.name); } private: std::string name; }; </code></pre> <p>This will get you implicit copy and move semantics which forward to std::string's copy and move members. And the author of std::string knows best how to get those operations done.</p> <p>If your compiler does not yet support implicit move generation, but does support defaulted special members, you can do this instead:</p> <pre><code>struct my_type { my_type(std::string name_) : name(std::move(name_)) {} my_type(const mytype&amp;) = default; my_type&amp; operator=(const mytype&amp;) = default; my_type(mytype&amp;&amp;) = default; my_type&amp; operator=(mytype&amp;&amp;) = default; void swap(my_type &amp;other) { name.swap(other.name); } private: std::string name; }; </code></pre> <p>You may also choose to do the above if you simply want to be explicit about your special members.</p> <p>If you're dealing with a compiler that does not yet support defaulted special members (or implicit move members), then you can explicitly supply what the compiler should eventually default when it becomes fully C++11 conforming:</p> <pre><code>struct my_type { my_type(std::string name_) : name(std::move(name_)) {} my_type(const mytype&amp; other) : name(other.name) {} my_type&amp; operator=(const mytype&amp; other) { name = other.name; return *this; } my_type(mytype&amp;&amp; other) : name(std::move(other.name)) {} my_type&amp; operator=(mytype&amp;&amp; other) { name = std::move(other.name); return *this; } void swap(my_type &amp;other) { name.swap(other.name); } private: std::string name; }; </code></pre> <p>If you really need strong exception safety for assignment, design it once and be explicit about it (edit to include suggestion by Luc Danton):</p> <pre><code>template &lt;class C&gt; typename std::enable_if &lt; std::is_nothrow_move_assignable&lt;C&gt;::value, C&amp; &gt;::type strong_assign(C&amp; c, C other) { c = std::move(other); return c; } template &lt;class C&gt; typename std::enable_if &lt; !std::is_nothrow_move_assignable&lt;C&gt;::value, C&amp; &gt;::type strong_assign(C&amp; c, C other) { using std::swap; static_assert(std::is_nothrow_swappable_v&lt;C&gt;, // C++17 only "Not safe if you move other into this function"); swap(c, other); return c; } </code></pre> <p>Now your clients can choose between efficiency (my type::operator=), or strong exception safety using <code>strong_assign</code>.</p>
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    1. COThanks for the great response. My problem is how do I know whether the compiler is actually choosing to do these properly. With move semantics I starting to return "on the stack" heavier and heavier objects with the knowledge that move semantics make it cheap. Of course if the the compiler is doing as I hope the then I am actively shooting myself in the foot by copying lots of strings and other heavy containers. Non the less thanks for your answer I will do as you advise.
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    2. CO@111: if the object is "heavy", then I wonder if move semantics are important. Move semantics are useful for *light* controller objects that manage a heavy *resource*, where deep copying of the resource is undesirable or impossible.
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    3. CO@111111: You'll know what the compiler is doing because it is completely specified. Just like the defaulted copy is specified by copying each base and member, defaulted move is specified by moving each base and member. If that's the right thing for your class, then go with the default, else write it yourself or disable it (no different than dealing with copy). For types like `std::string`, you should be able to count on them having a fast move constructor and move assignment. If you're unsure, measure. There's a great new `<chrono>` header making it very simple to do accurate timings! :-)
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