qptrcollection(3qt)

1QPtrCollection(3qt)                                        QPtrCollection(3qt)
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NAME

6       QPtrCollection - The base class of most pointer-based Qt collections
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SYNOPSIS

9       All the functions in this class are reentrant when Qt is built with
10       thread support.</p>
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12       #include <qptrcollection.h>
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14       Inherited by QAsciiCache, QAsciiDict, QCache, QDict, QIntCache,
15       QIntDict, QPtrList, QPtrDict, and QPtrVector.
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17   Public Members
18       bool autoDelete () const
19       void setAutoDelete ( bool enable )
20       virtual uint count () const = 0
21       virtual void clear () = 0
22       typedef void * Item
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24   Protected Members
25       QPtrCollection ()
26       QPtrCollection ( const QPtrCollection & source )
27       virtual ~QPtrCollection ()
28       virtual Item newItem ( Item d )
29       virtual void deleteItem ( Item d ) = 0
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DESCRIPTION

32       The QPtrCollection class is the base class of most pointer-based Qt
33       collections.
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35       The QPtrCollection class is an abstract base class for the Qt
36       collection classes QDict, QPtrList, etc. Qt also includes value based
37       collections, e.g. QValueList, QMap, etc.
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39       A QPtrCollection only knows about the number of objects in the
40       collection and the deletion strategy (see setAutoDelete()).
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42       A collection is implemented using the Item (generic collection item)
43       type, which is a void*. The template classes that create the real
44       collections cast the Item to the required type.
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46       See also Collection Classes and Non-GUI Classes.
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48   Member Type Documentation

QPtrCollection::Item

50       This type is the generic "item" in a QPtrCollection.
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MEMBER FUNCTION DOCUMENTATION

QPtrCollection::QPtrCollection () [protected]

54       Constructs a collection. The constructor is protected because
55       QPtrCollection is an abstract class.
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QPtrCollection::QPtrCollection ( const QPtrCollection & source ) [protected]

58       Constructs a copy of source with autoDelete() set to FALSE. The
59       constructor is protected because QPtrCollection is an abstract class.
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61       Note that if source has autoDelete turned on, copying it will risk
62       memory leaks, reading freed memory, or both.
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QPtrCollection::~QPtrCollection () [virtual protected]

65       Destroys the collection. The destructor is protected because
66       QPtrCollection is an abstract class.
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bool QPtrCollection::autoDelete () const

69       Returns the setting of the auto-delete option. The default is FALSE.
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71       See also setAutoDelete().
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void QPtrCollection::clear () [pure virtual]

74       Removes all objects from the collection. The objects will be deleted if
75       auto-delete has been enabled.
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77       See also setAutoDelete().
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79       Reimplemented in QAsciiCache, QAsciiDict, QCache, QDict, QIntCache,
80       QIntDict, QPtrList, QPtrDict, and QPtrVector.
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uint QPtrCollection::count () const [pure virtual]

83       Returns the number of objects in the collection.
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85       Reimplemented in QAsciiCache, QAsciiDict, QCache, QDict, QIntCache,
86       QIntDict, QPtrList, QPtrDict, and QPtrVector.
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void QPtrCollection::deleteItem ( Item d ) [pure virtual protected]

89       Reimplement this function if you want to be able to delete items.
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91       Deletes an item that is about to be removed from the collection.
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93       This function has to reimplemented in the collection template classes,
94       and should only delete item d if auto-delete has been enabled.
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96       Warning: If you reimplement this function you must also reimplement the
97       destructor and call the virtual function clear() from your destructor.
98       This is due to the way virtual functions and destructors work in C++:
99       Virtual functions in derived classes cannot be called from a
100       destructor. If you do not do this, your deleteItem() function will not
101       be called when the container is destroyed.
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103       See also newItem() and setAutoDelete().
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Item QPtrCollection::newItem ( Item d ) [virtual protected]

106       Virtual function that creates a copy of an object that is about to be
107       inserted into the collection.
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109       The default implementation returns the d pointer, i.e. no copy is made.
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111       This function is seldom reimplemented in the collection template
112       classes. It is not common practice to make a copy of something that is
113       being inserted.
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115       See also deleteItem().
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void QPtrCollection::setAutoDelete ( bool enable )

118       Sets the collection to auto-delete its contents if enable is TRUE and
119       to never delete them if enable is FALSE.
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121       If auto-deleting is turned on, all the items in a collection are
122       deleted when the collection itself is deleted. This is convenient if
123       the collection has the only pointer to the items.
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125       The default setting is FALSE, for safety. If you turn it on, be careful
126       about copying the collection - you might find yourself with two
127       collections deleting the same items.
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129       Note that the auto-delete setting may also affect other functions in
130       subclasses. For example, a subclass that has a remove() function will
131       remove the item from its data structure, and if auto-delete is enabled,
132       will also delete the item.
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134       See also autoDelete().
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136       Examples:
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COPYRIGHT

144       Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com.  See the
145       license file included in the distribution for a complete license
146       statement.
147

AUTHOR

149       Generated automatically from the source code.
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BUGS

152       If you find a bug in Qt, please report it as described in
153       http://doc.trolltech.com/bughowto.html.  Good bug reports help us to
154       help you. Thank you.
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156       The definitive Qt documentation is provided in HTML format; it is
157       located at $QTDIR/doc/html and can be read using Qt Assistant or with a
158       web browser. This man page is provided as a convenience for those users
159       who prefer man pages, although this format is not officially supported
160       by Trolltech.
161
162       If you find errors in this manual page, please report them to qt-
163       bugs@trolltech.com.  Please include the name of the manual page
164       (qptrcollection.3qt) and the Qt version (3.3.8).
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168Trolltech AS                    2 February 2007            QPtrCollection(3qt)