| 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> |
|---|
| 2 | <html> |
|---|
| 3 | <head> |
|---|
| 4 | <title>scoped_array</title> |
|---|
| 5 | <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> |
|---|
| 6 | </head> |
|---|
| 7 | <body bgcolor="#ffffff" text="#000000"> |
|---|
| 8 | <h1><A href="../../index.htm"><img src="../../boost.png" alt="boost.png (6897 bytes)" align="middle" width="277" height="86" |
|---|
| 9 | border="0"></A>scoped_array class template</h1> |
|---|
| 10 | <p>The <b>scoped_array</b> class template stores a pointer to a dynamically |
|---|
| 11 | allocated array. (Dynamically allocated arrays are allocated with the C++ <b>new[]</b> |
|---|
| 12 | expression.) The array pointed to is guaranteed to be deleted, either on |
|---|
| 13 | destruction of the <b>scoped_array</b>, or via an explicit <b>reset</b>.</p> |
|---|
| 14 | <p>The <b>scoped_array</b> template is a simple solution for simple needs. It |
|---|
| 15 | supplies a basic "resource acquisition is initialization" facility, without |
|---|
| 16 | shared-ownership or transfer-of-ownership semantics. Both its name and |
|---|
| 17 | enforcement of semantics (by being <a href="../utility/utility.htm#Class_noncopyable"> |
|---|
| 18 | noncopyable</a>) signal its intent to retain ownership solely within the |
|---|
| 19 | current scope. Because it is <a href="../utility/utility.htm#Class_noncopyable">noncopyable</a>, |
|---|
| 20 | it is safer than <b>shared_array</b> for pointers which should not be copied.</p> |
|---|
| 21 | <p>Because <b>scoped_array</b> is so simple, in its usual implementation every |
|---|
| 22 | operation is as fast as a built-in array pointer and it has no more space |
|---|
| 23 | overhead that a built-in array pointer.</p> |
|---|
| 24 | <p>It cannot be used in C++ standard library containers. See <a href="shared_array.htm"> |
|---|
| 25 | <b>shared_array</b></a> if <b>scoped_array</b> does not meet your needs.</p> |
|---|
| 26 | <p>It cannot correctly hold a pointer to a single object. See <a href="scoped_ptr.htm"><b>scoped_ptr</b></a> |
|---|
| 27 | for that usage.</p> |
|---|
| 28 | <p>A <b>std::vector</b> is an alternative to a <b>scoped_array</b> that is a bit |
|---|
| 29 | heavier duty but far more flexible. A <b>boost::array</b> is an alternative |
|---|
| 30 | that does not use dynamic allocation.</p> |
|---|
| 31 | <p>The class template is parameterized on <b>T</b>, the type of the object pointed |
|---|
| 32 | to. <b>T</b> must meet the smart pointer <a href="smart_ptr.htm#common_requirements"> |
|---|
| 33 | common requirements</a>.</p> |
|---|
| 34 | <h2>Synopsis</h2> |
|---|
| 35 | <pre>namespace boost { |
|---|
| 36 | |
|---|
| 37 | template<class T> class scoped_array : <a href="../utility/utility.htm#Class_noncopyable">noncopyable</a> { |
|---|
| 38 | |
|---|
| 39 | public: |
|---|
| 40 | typedef T <a href="#element_type">element_type</a>; |
|---|
| 41 | |
|---|
| 42 | explicit <a href="#ctor">scoped_array</a>(T * p = 0); // never throws |
|---|
| 43 | <a href="#destructor">~scoped_array</a>(); // never throws |
|---|
| 44 | |
|---|
| 45 | void <a href="#reset">reset</a>(T * p = 0); // never throws |
|---|
| 46 | |
|---|
| 47 | T & <a href="#operator[]">operator[]</a>(std::ptrdiff_t i) const; // never throws |
|---|
| 48 | T * <a href="#get">get</a>() const; // never throws |
|---|
| 49 | |
|---|
| 50 | operator <A href="#conversions" ><i>unspecified-bool-type</i></A>() const; // never throws |
|---|
| 51 | |
|---|
| 52 | void <a href="#swap">swap</a>(scoped_array & b); // never throws |
|---|
| 53 | }; |
|---|
| 54 | |
|---|
| 55 | template<class T> void <a href="#free-swap">swap</a>(scoped_array<T> & a, scoped_array<T> & b); // never throws |
|---|
| 56 | |
|---|
| 57 | }</pre> |
|---|
| 58 | <h2>Members</h2> |
|---|
| 59 | <h3> |
|---|
| 60 | <a name="element_type">element_type</a></h3> |
|---|
| 61 | <pre>typedef T element_type;</pre> |
|---|
| 62 | <p>Provides the type of the stored pointer.</p> |
|---|
| 63 | <h3><a name="ctor">constructors</a></h3> |
|---|
| 64 | <pre>explicit scoped_array(T * p = 0); // never throws</pre> |
|---|
| 65 | <p>Constructs a <b>scoped_array</b>, storing a copy of <b>p</b>, which must have |
|---|
| 66 | been allocated via a C++ <b>new</b>[] expression or be 0. <b>T</b> is not |
|---|
| 67 | required be a complete type. See the smart pointer <a href="smart_ptr.htm#common_requirements"> |
|---|
| 68 | common requirements</a>.</p> |
|---|
| 69 | <h3><a name="destructor">destructor</a></h3> |
|---|
| 70 | <pre>~scoped_array(); // never throws</pre> |
|---|
| 71 | <p>Deletes the array pointed to by the stored pointer. Note that <b>delete[]</b> on |
|---|
| 72 | a pointer with a value of 0 is harmless. The guarantee that this does not throw |
|---|
| 73 | exceptions depends on the requirement that the deleted array's objects' |
|---|
| 74 | destructors do not throw exceptions. See the smart pointer <a href="smart_ptr.htm#common_requirements"> |
|---|
| 75 | common requirements</a>.</p> |
|---|
| 76 | <h3><a name="reset">reset</a></h3> |
|---|
| 77 | <pre>void reset(T * p = 0); // never throws</pre> |
|---|
| 78 | <p> |
|---|
| 79 | Deletes the array pointed to by the stored pointer and then stores a copy of p, |
|---|
| 80 | which must have been allocated via a C++ <b>new[]</b> expression or be 0. The |
|---|
| 81 | guarantee that this does not throw exceptions depends on the requirement that |
|---|
| 82 | the deleted array's objects' destructors do not throw exceptions. See the smart |
|---|
| 83 | pointer <a href="smart_ptr.htm#common_requirements">common requirements</a>.</p> |
|---|
| 84 | <h3><a name="operator[]">subscripting</a></h3> |
|---|
| 85 | <pre>T & operator[](std::ptrdiff_t i) const; // never throws</pre> |
|---|
| 86 | <p>Returns a reference to element <b>i</b> of the array pointed to by the stored |
|---|
| 87 | pointer. Behavior is undefined and almost certainly undesirable if the stored |
|---|
| 88 | pointer is 0, or if <b>i</b> is less than 0 or is greater than or equal to the |
|---|
| 89 | number of elements in the array.</p> |
|---|
| 90 | <h3><a name="get">get</a></h3> |
|---|
| 91 | <pre>T * get() const; // never throws</pre> |
|---|
| 92 | <p>Returns the stored pointer. <b>T</b> need not be a complete type. See the smart |
|---|
| 93 | pointer <a href="smart_ptr.htm#common_requirements">common requirements</a>.</p> |
|---|
| 94 | <h3><a name="conversions">conversions</a></h3> |
|---|
| 95 | <pre>operator <i>unspecified-bool-type</i> () const; // never throws</pre> |
|---|
| 96 | <p>Returns an unspecified value that, when used in boolean contexts, is equivalent |
|---|
| 97 | to <code>get() != 0</code>.</p> |
|---|
| 98 | <h3><a name="swap">swap</a></h3> |
|---|
| 99 | <pre>void swap(scoped_array & b); // never throws</pre> |
|---|
| 100 | <p>Exchanges the contents of the two smart pointers. <b>T</b> need not be a |
|---|
| 101 | complete type. See the smart pointer <a href="smart_ptr.htm#common_requirements">common |
|---|
| 102 | requirements</a>.</p> |
|---|
| 103 | <h2><a name="functions">Free Functions</a></h2> |
|---|
| 104 | <h3><a name="free-swap">swap</a></h3> |
|---|
| 105 | <pre>template<class T> void swap(scoped_array<T> & a, scoped_array<T> & b); // never throws</pre> |
|---|
| 106 | <p>Equivalent to <b>a.swap(b)</b>. Matches the interface of <b>std::swap</b>. |
|---|
| 107 | Provided as an aid to generic programming.</p> |
|---|
| 108 | <hr> |
|---|
| 109 | <p>Revised <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B %Y" startspan--> |
|---|
| 110 | 09 January 2003<!--webbot bot="Timestamp" endspan i-checksum="32310"--></p> |
|---|
| 111 | <p>Copyright 1999 Greg Colvin and Beman Dawes. Copyright 2002 Darin Adler. |
|---|
| 112 | Copyright 2002-2005 Peter Dimov. Permission to copy, use, modify, sell and |
|---|
| 113 | distribute this document is granted provided this copyright notice appears in |
|---|
| 114 | all copies. This document is provided "as is" without express or implied |
|---|
| 115 | warranty, and with no claim as to its suitability for any purpose.</p> |
|---|
| 116 | </body> |
|---|
| 117 | </html> |
|---|
