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<title>scoped_array</title>
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<h1><img src="../../c++boost.gif" alt="c++boost.gif (8819 bytes)" align="center" width="277" height="86">Class
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<a name="scoped_array">scoped_array</a></h1>
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<p>Class <strong>scoped_array</strong> stores a pointer to a dynamically
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allocated array. (Dynamically allocated arrays are allocated with the C++ <tt>new[]</tt>
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expression.) The array pointed to is guaranteed to be deleted,
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either on destruction of the <strong>scoped_array</strong>, or via an explicit <strong>scoped_array::reset()</strong>.</p>
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<p>Class<strong> scoped_array</strong> is a simple solution for simple
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2001-05-10 16:00:49 +00:00
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needs. It supplies a basic "resource acquisition is
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initialization" facility, without shared-ownership or transfer-of-ownership
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semantics. Both its name and enforcement of semantics (by being <a href="../utility/utility.htm#class noncopyable">noncopyable</a>)
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signal its intent to retain ownership solely within the current scope. By
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being <a href="../utility/utility.htm#class noncopyable">noncopyable</a>, it is
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safer than <b>shared_array</b> for pointers which should not be copied.</p>
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<p>Because <strong>scoped_array</strong> is so simple, in its usual
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implementation every operation is as fast as a built-in array pointer and it has no
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more space overhead that a built-in array pointer.</p>
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<p>It cannot be used in C++ Standard Library containers. See <a href="shared_array.htm"><strong>shared_array</strong></a>
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if <strong>scoped_array</strong> does not meet your needs.</p>
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<p>Class<strong> scoped_array</strong> cannot correctly hold a pointer to a
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single object. See <a href="scoped_ptr.htm"><strong>scoped_ptr</strong></a>
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for that usage.</p>
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2001-05-10 16:00:49 +00:00
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<p>A C++ Standard Library <strong>vector</strong> is a <strong> </strong>heavier duty alternative to a <strong>scoped_array</strong>.</p>
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<p>The class is a template parameterized on <tt>T</tt>, the type of the object
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pointed to. <tt>T</tt> must meet the smart pointer <a href="smart_ptr.htm#Common requirements">common
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requirements</a>.</p>
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<h2>Class scoped_array Synopsis</h2>
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<pre>#include <<a href="../../boost/smart_ptr.hpp">boost/smart_ptr.hpp</a>>
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namespace boost {
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template<typename T> class scoped_array : <a href="../utility/utility.htm#noncopyable">noncopyable</a> {
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public:
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typedef T <a href="#scoped_array_element_type">element_type</a>;
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explicit <a href="#scoped_array_ctor">scoped_array</a>( T* p=0 ); // never throws
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<strong> </strong><a href="#scoped_array_~scoped_array">~scoped_array</a>();
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void <a href="#scoped_array_reset">reset</a>( T* p=0 );
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T& <a href="#scoped_array_operator[]">operator[]</a>(std::size_t i) const; // never throws
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T* <a href="#scoped_array_get">get</a>() const; // never throws
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};
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}</pre>
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<h2>Class scoped_array Members</h2>
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<h3>scoped_array <a name="scoped_array_element_type">element_type</a></h3>
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<pre>typedef T element_type;</pre>
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<p>Provides the type of the stored pointer.</p>
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<h3><a name="scoped_array_ctor">scoped_array constructors</a></h3>
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<pre>explicit scoped_array( T* p=0 ); // never throws</pre>
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<p>Constructs a <tt>scoped_array</tt>, storing a copy of <tt>p</tt>, which must
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have been allocated via a C++ <tt>new</tt>[] expression or be 0.</p>
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<p><b>T</b> is not required be a complete type.
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See <a href="smart_ptr.htm#Common requirements">Common Requirements</a>.</p>
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<h3><a name="scoped_array_~scoped_array">scoped_array destructor</a></h3>
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<pre>~scoped_array();</pre>
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<p>Deletes the array pointed to by the stored pointer. Note that in C++ <tt>delete</tt>[]
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on a pointer with a value of 0 is harmless.</p>
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<p>Does not throw exceptions.</p>
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<h3>scoped_array <a name="scoped_array_reset">reset</a></h3>
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<pre>void reset( T* p=0 )();</pre>
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<p>If p is not equal to the stored pointer, deletes the array pointed to by the
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stored pointer and then stores a copy of p, which must have been allocated via a
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C++ <tt>new[]</tt> expression or be 0.</p>
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<p>Does not throw exceptions.</p>
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<h3>scoped_array <a name="scoped_array_operator[]">operator[]</a></h3>
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<p><tt>T& operator[](std::size_t i) const; // never throws</tt></p>
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<p>Returns a reference to element <tt>i</tt> of the array pointed to by the
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stored pointer.</p>
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<p>Behavior is undefined (and almost certainly undesirable) if <tt>get()==0</tt>,
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or if <tt>i</tt> is less than 0 or is greater or equal to the number of elements
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in the array.</p>
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<h3>scoped_array <a name="scoped_array_get">get</a></h3>
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<pre>T* get() const; // never throws</pre>
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<p><b>T</b> is not required be a complete type.
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See <a href="smart_ptr.htm#Common requirements">Common Requirements</a>.</p>
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<p>Returns the stored pointer.</p>
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<h2>Class <a name="shared_array_example">scoped_array example</a></h2>
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<p>[To be supplied. In the meantime, see <a href="smart_ptr_test.cpp">smart_ptr_test.cpp</a>.]</p>
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<hr>
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<p>Revised <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan
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-->24 May, 2001<!--webbot bot="Timestamp" endspan i-checksum="13964"
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-->
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</p>
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2000-07-27 14:27:00 +00:00
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<p><EFBFBD> Copyright Greg Colvin and Beman Dawes 1999. Permission to copy, use,
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modify, sell and distribute this document is granted provided this copyright
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notice appears in all copies. This document is provided "as is"
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without express or implied warranty, and with no claim as to its suitability for
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any purpose.</p>
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