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C++11 rvalue reference docs updated.

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William S Fulton 2014-03-03 19:12:12 +00:00
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@ -62,12 +62,15 @@
<p>This chapter gives you a brief overview about the SWIG <p>This chapter gives you a brief overview about the SWIG
implementation of the C++11 standard. This part of SWIG is still a work in implementation of the C++11 standard. This part of SWIG is still a work in
progress. Initial C++11 support for SWIG was written during the progress.
Google Summer of Code 2009 period.</p> </p>
<p>SWIG supports all the new C++ syntax changes with some minor limitations <p>SWIG supports the new C++ syntax changes with some minor limitations
(decltype expressions, variadic templates number). Wrappers for the (decltype expressions, variadic templates number). Wrappers for the
new STL types (unordered_ containers, result_of, tuples) are not supported new STL types (unordered_ containers, result_of, tuples) are incomplete.
yet.</p> The wrappers for the new containers would work much like the C++03 containers and
users are welcome to help by adapting the existing container interface files and submitting them
as a patch for inclusion in future versions of SWIG.
</p>
<H2><a name="CPlusPlus11_core_language_changes"></a>7.2 Core language changes</H2> <H2><a name="CPlusPlus11_core_language_changes"></a>7.2 Core language changes</H2>
@ -75,19 +78,45 @@ yet.</p>
<H3><a name="CPlusPlus11_rvalue_reference_and_move_semantics"></a>7.2.1 Rvalue reference and move semantics</H3> <H3><a name="CPlusPlus11_rvalue_reference_and_move_semantics"></a>7.2.1 Rvalue reference and move semantics</H3>
<p>SWIG correctly parses the new operator &amp;&amp; the same as the reference operator &amp;.</p> <p>
SWIG correctly parses the rvalue reference syntax '&amp;&amp;',
for example the typical usage of it in the move constructor and move assignment operator below:
</p>
<p>The wrapper for the following code is correctly produced:</p>
<div class="code"><pre> <div class="code"><pre>
class MyClass { class MyClass {
MyClass(MyClass&amp;&amp; p) : ptr(p.ptr) {p.ptr = 0;} ...
MyClass&amp; operator=(MyClass&amp;&amp; p) { std::vector<int> numbers;
std::swap(ptr, p.ptr); public:
MyClass(MyClass &amp;&amp;other) : numbers(std::move(other.numbers)) {}
MyClass &amp; operator=(MyClass &amp;&amp;other) {
numbers = std::move(other.numbers);
return *this; return *this;
} }
}; };
</pre></div> </pre></div>
<p>
Rvalue references are designed for C++ temporaries and so are not very useful when used from non-C++ target languages.
Generally you would just ignore them via <tt>%ignore</tt> before parsing the class.
For example, ignore the move constructor:
</p>
<div class="code"><pre>
%ignore MyClass::MyClass(MyClass &amp;&amp;);
</pre></div>
<p>
The plan is to ignore them by default in a future version of SWIG. Note that both normal assignment operators as well as move assignment operators are ignored by default in most target languages with the following warning:
</p>
<div class="shell">
<pre>
example.i:18: Warning 503: Can't wrap 'operator =' unless renamed to a valid identifier.
</pre>
</div>
<H3><a name="CPlusPlus11_generalized_constant_expressions"></a>7.2.2 Generalized constant expressions</H3> <H3><a name="CPlusPlus11_generalized_constant_expressions"></a>7.2.2 Generalized constant expressions</H3>