forked from boostorg/smart_ptr
Improve documentation for make_shared for arrays
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Glen Fernandes
+96
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<body text="#000000" bgcolor="#ffffff" link="#0000ff" vlink="#0000ff">
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<h1><img height="86" alt="boost.png (6897 bytes)" src="../../boost.png"
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width="277" align="middle" border="0">make_unique</h1>
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<p><a href="#Introduction">Introduction</a><br>
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<a href="#Synopsis">Synopsis</a><br>
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<p><a href="#introduction">Introduction</a><br>
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<a href="#synopsis">Synopsis</a><br>
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<a href="#common">Common Requirements</a><br>
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<a href="#functions">Free Functions</a><br>
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<a href="#example">Examples</a><br>
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<a href="#history">History</a></p>
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<h2><a name="Introduction">Introduction</a></h2>
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<h2><a name="introduction">Introduction</a></h2>
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<p>The header file <boost/make_unique.hpp> provides overloaded
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function template <code>make_unique</code> for convenient creation of
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<code>unique_ptr</code> objects.</p>
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<h2><a name="Synopsis">Synopsis</a></h2>
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<h2><a name="synopsis">Synopsis</a></h2>
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<pre>namespace boost {
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template<typename U> // U is not array
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unique_ptr<U> <a href="#functions">make_unique</a>();
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@@ -29,103 +29,127 @@
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template<typename U> // U is not array
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unique_ptr<U> <a href="#functions">make_unique</a>(U&& value);
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template<typename U> // U is T[]
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unique_ptr<U> <a href="#functions">make_unique</a>(size_t size);
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template<typename U> // U is not array
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unique_ptr<U> <a href="#functions">make_unique_noinit</a>();
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template<typename U> // U is T[]
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unique_ptr<U> <a href="#functions">make_unique</a>(size_t size);
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template<typename U> // U is T[]
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unique_ptr<U> <a href="#functions">make_unique_noinit</a>(size_t size);
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}</pre>
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<h2><a name="functions">Free Functions</a></h2>
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<pre>template<typename U> // U is not array
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unique_ptr<U> make_unique();</pre>
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<h2><a name="common">Common Requirements</a></h2>
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<pre>template<typename U>
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unique_ptr<U> make_unique(<em>args</em>);
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template<typename U>
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unique_ptr<U> make_unique_noinit(<em>args</em>);</pre>
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<blockquote>
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<p><b>Requires:</b> The expression <code>new U()</code> shall be
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well-formed.</p>
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<p><b>Effects:</b> Constructs an object of type <code>U</code> via the
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expression <code>new U()</code>.</p>
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<p><b>Effects:</b> Allocates memory for an object of type <code>U</code>
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(or <code>T[size]</code> when <code>U</code> is <code>T[]</code>,
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where <code>size</code> is determined from <code>args</code> as
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specified by the concrete overload). The object is initialized from
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<code>args</code> as specified by the concrete overload. If an
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exception is thrown, the functions have no effect.</p>
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<p><b>Returns:</b> A <code>unique_ptr</code> instance that stores and
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owns the address of the newly constructed object.</p>
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<p><b>Postconditions:</b> <code>get() != 0</code>.</p>
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<p><b>Postconditions:</b> <code>r.get() != 0</code>, where
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<code>r</code> is the return value.</p>
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<p><b>Throws:</b> <code>bad_alloc</code>, or an exception thrown from
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the constructor of <code>U</code>.</p>
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the initialization of the object.</p>
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</blockquote>
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<pre>template<typename U, typename... Args> // U is not array
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unique_ptr<U> make_unique(Args&&... args);</pre>
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<blockquote>
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<p><b>Requires:</b> The expression
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<code>new U(forward<Args>(args)...)</code> shall be
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well-formed.</p>
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<p><b>Effects:</b> Constructs an object of type <code>U</code> via the
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expression <code>new U(forward<Args>(args)...)</code>.</p>
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<p><b>Remarks:</b></p>
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<blockquote>
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<p>When an object of a non-array type <code>T</code> is specified to
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be initialized to a value <code>value</code>, or to
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<code>T(list...)</code>, where <code>list...</code> is a list of
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constructor arguments, <code>make_unique</code> shall perform this
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initialization via the expression <code>new T(value)</code> or
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<code>new T(list...)</code> respectively.</p>
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<p>When an object of type <code>T</code> is specified to be
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value-initialized, <code>make_unique</code> shall perform this
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initialization via the expression <code>new T()</code>.</p>
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<p>When an object of type <code>T</code> is specified to be
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default-initialized, <code>make_unique_noinit</code> shall perform
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this initialization via the expression <code>new T</code>.</p>
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</blockquote>
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</blockquote>
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<pre>template<typename U> // U is not array
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<h2><a name="functions">Free Functions</a></h2>
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<pre>template<typename U, typename... Args>
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unique_ptr<U> make_unique(Args&&... args);</pre>
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<blockquote>
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<p><b>Returns:</b> A unique_ptr to an object of type <code>U</code>,
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initialized to <code>U(forward<Args>(args)...)</code>.</p>
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<p><b>Remarks:</b> This overload shall only participate in overload
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resolution when <code>U</code> is not an array type.</p>
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</blockquote>
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<blockquote>
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<p><b>Examples:</b></p>
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<blockquote>
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<pre>unique_ptr<float> p1 = boost::make_unique<float>();
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unique_ptr<point> p2 = boost::make_unique<point>(x, y);</pre>
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</blockquote>
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</blockquote>
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<pre>template<typename U>
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unique_ptr<U> make_unique(U&& value);</pre>
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<blockquote>
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<p><b>Requires:</b> The expression <code>new U(move(value))</code> shall
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be well-formed.</p>
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<p><b>Effects:</b> Constructs an object of type <code>U</code> via the
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expression <code>new U(move(value))</code>.</p>
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<p><b>Returns:</b> A unique_ptr to an object of type <code>U</code>,
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initialized to <code>move(value)</code>.</p>
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<p><b>Remarks:</b> This overload shall only participate in overload
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resolution when <code>U</code> is not an array type.</p>
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</blockquote>
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<pre>template<typename U> // U is not array
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unique_ptr<U> make_unique_noinit();</pre>
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<blockquote>
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<p><b>Requires:</b> The expression <code>new U</code> shall be
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well-formed.</p>
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<p><b>Effects:</b> Constructs an object of type <code>U</code> via the
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expression <code>new U</code>.</p>
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<p><b>Examples:</b></p>
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<blockquote>
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<pre>unique_ptr<string> p1 = boost::make_unique<string>({'a', 'b'});
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unique_ptr<point> p2 = boost::make_unique<point>({-10, 25});</pre>
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</blockquote>
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</blockquote>
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<pre>template<typename U> // U is T[]
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unique_ptr<U> make_unique(size_t size);</pre>
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<pre>template<typename U>
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unique_ptr<U> make_unique(size_t size);</pre>
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<blockquote>
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<p><b>Requires:</b> The expression <code>new T[size]()</code> shall be
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well-formed.</p>
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<p><b>Effects:</b> Constructs an array of objects of type
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<code>U</code> and size <code>size</code> via the expression
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<code>new T[size]()</code>.</p>
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<p><b>Returns:</b> A unique_ptr to a value-initialized object of type
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<code>T[size]</code>.</p>
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<p><b>Remarks:</b> This overload shall only participate in overload
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resolution when <code>U</code> is of the form <code>T[]</code>.</p>
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</blockquote>
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<pre>template<typename U> // U is T[]
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unique_ptr<U> make_unique_noinit(size_t size);</pre>
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<blockquote>
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<p><b>Requires:</b> The expression <code>new T[size]</code> shall be
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well-formed.</p>
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<p><b>Effects:</b> Constructs an array of objects of type
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<code>U</code> and size <code>size</code> via the expression
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<code>new T[size]</code>.</p>
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</blockquote>
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<h2><a name="example">Examples</a></h2>
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<p>For objects with value-initialization.</p>
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<blockquote>
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<pre>unique_ptr<float> p1 = boost::make_unique<float>();
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unique_ptr<point> p2 = boost::make_unique<point>();</pre>
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<p><b>Examples:</b></p>
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<blockquote>
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<pre>unique_ptr<double[]> p1 = boost::make_unique<double[]>(4);
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unique_ptr<int[][2]> p2 = boost::make_unique<int[][2]>(2);</pre>
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</blockquote>
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</blockquote>
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<p>For objects with construction arguments.</p>
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<pre>template<typename U>
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unique_ptr<U> make_unique_noinit();</pre>
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<blockquote>
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<pre>unique_ptr<float> p3 = boost::make_unique<float>(1.0f);
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unique_ptr<point> p4 = boost::make_unique<point>(x, y);</pre>
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<p><b>Returns:</b> A unique_ptr to a default-initialized object of
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type <code>U</code>.</p>
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<p><b>Remarks:</b> This overload shall only participate in overload
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resolution when <code>U</code> is not an array type.</p>
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</blockquote>
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<p>For objects with given value.</p>
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<blockquote>
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<pre>unique_ptr<string> p4 = boost::make_unique<string>({'a', 'b'});
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unique_ptr<type> p5 = boost::make_unique<type>({3, 5, 4});</pre>
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<p><b>Examples:</b></p>
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<blockquote>
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<pre>unique_ptr<float> p1 = boost::make_unique_noinit<float>();
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unique_ptr<point> p2 = boost::make_unique_noinit<point>();</pre>
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</blockquote>
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</blockquote>
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<p>For objects with default-initialization.</p>
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<pre>template<typename U>
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unique_ptr<U> make_unique_noinit(size_t size);</pre>
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<blockquote>
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<pre>unique_ptr<float> p6 = boost::make_unique_noinit<float>();
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unique_ptr<point> p7 = boost::make_unique_noinit<point>();</pre>
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<p><b>Returns:</b> A unique_ptr to a default-initialized object of
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type <code>T[size]</code>.</p>
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<p><b>Remarks:</b> This overload shall only participate in overload
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resolution when <code>U</code> is of the form <code>T[]</code>.</p>
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</blockquote>
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<p>For arrays with value-initialization.</p>
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<blockquote>
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<pre>unique_ptr<double[]> a1 = boost::make_unique<double[]>();
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unique_ptr<int[][4]> a2 = boost::make_unique<int[][4]>();</pre>
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<p><b>Examples:</b></p>
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<blockquote>
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<pre>unique_ptr<double[]> p1 = boost::make_unique_noinit<double[]>(4);
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unique_ptr<int[][2]> p2 = boost::make_unique_noinit<int[][2]>(2);</pre>
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</blockquote>
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</blockquote>
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<p>For arrays with default-initialization.</p>
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<blockquote>
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<pre>unique_ptr<double[]> a3 = boost::make_unique_noinit<double[]>();
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unique_ptr<int[][4]> a4 = boost::make_unique_noinit<int[][4]>();</pre>
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</blockquote>
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<h2><a name="history">History</a></h2>
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<p>January 2014. Glen Fernandes contributed implementations of
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make_unique for objects and arrays.</p>
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