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32<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QPtrCollection Class Reference</h1>
33
34<p>The QPtrCollection class is the base class of most pointer-based Qt collections.
35<a href="#details">More...</a>
36<p>All the functions in this class are <a href="threads.html#reentrant">reentrant</a> when Qt is built with thread support.</p>
37<p><tt>#include &lt;<a href="qptrcollection-h.html">qptrcollection.h</a>&gt;</tt>
38<p>Inherited by <a href="qasciicache.html">QAsciiCache</a>, <a href="qasciidict.html">QAsciiDict</a>, <a href="qcache.html">QCache</a>, <a href="qdict.html">QDict</a>, <a href="qintcache.html">QIntCache</a>, <a href="qintdict.html">QIntDict</a>, <a href="qptrlist.html">QPtrList</a>, <a href="qptrdict.html">QPtrDict</a>, and <a href="qptrvector.html">QPtrVector</a>.
39<p><a href="qptrcollection-members.html">List of all member functions.</a>
40<h2>Public Members</h2>
41<ul>
42<li class=fn>bool <a href="#autoDelete"><b>autoDelete</b></a> () const</li>
43<li class=fn>void <a href="#setAutoDelete"><b>setAutoDelete</b></a> ( bool&nbsp;enable )</li>
44<li class=fn>virtual uint <a href="#count"><b>count</b></a> () const = 0</li>
45<li class=fn>virtual void <a href="#clear"><b>clear</b></a> () = 0</li>
46<li class=fn>typedef void&nbsp;*&nbsp;<a href="#Item"><b>Item</b></a></li>
47</ul>
48<h2>Protected Members</h2>
49<ul>
50<li class=fn><a href="#QPtrCollection"><b>QPtrCollection</b></a> ()</li>
51<li class=fn><a href="#QPtrCollection-2"><b>QPtrCollection</b></a> ( const&nbsp;QPtrCollection&nbsp;&amp;&nbsp;source )</li>
52<li class=fn>virtual <a href="#~QPtrCollection"><b>~QPtrCollection</b></a> ()</li>
53<li class=fn>virtual Item <a href="#newItem"><b>newItem</b></a> ( Item&nbsp;d )</li>
54<li class=fn>virtual void <a href="#deleteItem"><b>deleteItem</b></a> ( Item&nbsp;d ) = 0</li>
55</ul>
56<hr><a name="details"></a><h2>Detailed Description</h2>
57
58
59
60The QPtrCollection class is the base class of most pointer-based Qt collections.
61<p>
62
63<p> The QPtrCollection class is an abstract base class for the Qt
64<a href="collection.html">collection classes</a> <a href="qdict.html">QDict</a>, <a href="qptrlist.html">QPtrList</a>,
65etc. Qt also includes value based collections, e.g. <a href="qvaluelist.html">QValueList</a>,
66<a href="qmap.html">QMap</a>, etc.
67<p> A QPtrCollection only knows about the number of objects in the
68collection and the deletion strategy (see <a href="#setAutoDelete">setAutoDelete</a>()).
69<p> A collection is implemented using the <a href="#Item">Item</a> (generic collection
70item) type, which is a <tt>void*</tt>. The template classes that create
71the real collections cast the <a href="#Item">Item</a> to the required type.
72<p>See also <a href="collection.html">Collection Classes</a> and <a href="tools.html">Non-GUI Classes</a>.
73
74<hr><h2>Member Type Documentation</h2>
75<h3 class=fn><a name="Item"></a>QPtrCollection::Item</h3>
76
77<p> This type is the generic "item" in a QPtrCollection.
78
79<hr><h2>Member Function Documentation</h2>
80<h3 class=fn><a name="QPtrCollection"></a>QPtrCollection::QPtrCollection ()<tt> [protected]</tt>
81</h3>
82
83<p> Constructs a collection. The constructor is protected because
84QPtrCollection is an abstract class.
85
86<h3 class=fn><a name="QPtrCollection-2"></a>QPtrCollection::QPtrCollection ( const&nbsp;<a href="qptrcollection.html">QPtrCollection</a>&nbsp;&amp;&nbsp;source )<tt> [protected]</tt>
87</h3>
88
89<p> Constructs a copy of <em>source</em> with <a href="#autoDelete">autoDelete</a>() set to FALSE. The
90constructor is protected because QPtrCollection is an abstract
91class.
92<p> Note that if <em>source</em> has autoDelete turned on, copying it will
93risk memory leaks, reading freed memory, or both.
94
95<h3 class=fn><a name="~QPtrCollection"></a>QPtrCollection::~QPtrCollection ()<tt> [virtual protected]</tt>
96</h3>
97
98<p> Destroys the collection. The destructor is protected because
99QPtrCollection is an abstract class.
100
101<h3 class=fn>bool <a name="autoDelete"></a>QPtrCollection::autoDelete () const
102</h3>
103
104<p> Returns the setting of the auto-delete option. The default is FALSE.
105<p> <p>See also <a href="#setAutoDelete">setAutoDelete</a>().
106
107<h3 class=fn>void <a name="clear"></a>QPtrCollection::clear ()<tt> [pure virtual]</tt>
108</h3>
109
110<p> Removes all objects from the collection. The objects will be
111deleted if auto-delete has been enabled.
112<p> <p>See also <a href="#setAutoDelete">setAutoDelete</a>().
113
114<p>Reimplemented in <a href="qasciicache.html#clear">QAsciiCache</a>, <a href="qasciidict.html#clear">QAsciiDict</a>, <a href="qcache.html#clear">QCache</a>, <a href="qdict.html#clear">QDict</a>, <a href="qintcache.html#clear">QIntCache</a>, <a href="qintdict.html#clear">QIntDict</a>, <a href="qptrlist.html#clear">QPtrList</a>, <a href="qptrdict.html#clear">QPtrDict</a>, and <a href="qptrvector.html#clear">QPtrVector</a>.
115<h3 class=fn>uint <a name="count"></a>QPtrCollection::count () const<tt> [pure virtual]</tt>
116</h3>
117
118<p> Returns the number of objects in the collection.
119
120<p>Reimplemented in <a href="qasciicache.html#count">QAsciiCache</a>, <a href="qasciidict.html#count">QAsciiDict</a>, <a href="qcache.html#count">QCache</a>, <a href="qdict.html#count">QDict</a>, <a href="qintcache.html#count">QIntCache</a>, <a href="qintdict.html#count">QIntDict</a>, <a href="qptrlist.html#count">QPtrList</a>, <a href="qptrdict.html#count">QPtrDict</a>, and <a href="qptrvector.html#count">QPtrVector</a>.
121<h3 class=fn>void <a name="deleteItem"></a>QPtrCollection::deleteItem ( <a href="qptrcollection.html#Item">Item</a>&nbsp;d )<tt> [pure virtual protected]</tt>
122</h3>
123
124<p> Reimplement this function if you want to be able to delete items.
125<p> Deletes an item that is about to be removed from the collection.
126<p> This function has to reimplemented in the collection template
127classes, and should <em>only</em> delete item <em>d</em> if auto-delete has
128been enabled.
129<p> <b>Warning:</b> If you reimplement this function you must also
130reimplement the destructor and call the virtual function <a href="#clear">clear</a>()
131from your destructor. This is due to the way virtual functions and
132destructors work in C++: Virtual functions in derived classes
133cannot be called from a destructor. If you do not do this, your
134<a href="#deleteItem">deleteItem</a>() function will not be called when the container is
135destroyed.
136<p> <p>See also <a href="#newItem">newItem</a>() and <a href="#setAutoDelete">setAutoDelete</a>().
137
138<h3 class=fn><a href="qptrcollection.html#Item">Item</a> <a name="newItem"></a>QPtrCollection::newItem ( <a href="qptrcollection.html#Item">Item</a>&nbsp;d )<tt> [virtual protected]</tt>
139</h3>
140Virtual function that creates a copy of an object that is about to
141be inserted into the collection.
142<p> The default implementation returns the <em>d</em> pointer, i.e. no copy
143is made.
144<p> This function is seldom reimplemented in the collection template
145classes. It is not common practice to make a copy of something
146that is being inserted.
147<p> <p>See also <a href="#deleteItem">deleteItem</a>().
148
149<h3 class=fn>void <a name="setAutoDelete"></a>QPtrCollection::setAutoDelete ( bool&nbsp;enable )
150</h3>
151
152<p> Sets the collection to auto-delete its contents if <em>enable</em> is
153TRUE and to never delete them if <em>enable</em> is FALSE.
154<p> If auto-deleting is turned on, all the items in a collection are
155deleted when the collection itself is deleted. This is convenient
156if the collection has the only pointer to the items.
157<p> The default setting is FALSE, for safety. If you turn it on, be
158careful about copying the collection - you might find yourself
159with two collections deleting the same items.
160<p> Note that the auto-delete setting may also affect other functions
161in subclasses. For example, a subclass that has a remove()
162function will remove the item from its data structure, and if
163auto-delete is enabled, will also delete the item.
164<p> <p>See also <a href="#autoDelete">autoDelete</a>().
165
166<p>Examples: <a href="grapher-nsplugin-example.html#x2769">grapher/grapher.cpp</a>, <a href="scribble-example.html#x924">scribble/scribble.cpp</a>, and <a href="bigtable-example.html#x1291">table/bigtable/main.cpp</a>.
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