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| author | Timothy Pearson <kb9vqf@pearsoncomputing.net> | 2012-01-26 23:32:43 -0600 |
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| committer | Timothy Pearson <kb9vqf@pearsoncomputing.net> | 2012-01-26 23:32:43 -0600 |
| commit | ea318d1431c89e647598c510c4245c6571aa5f46 (patch) | |
| tree | 996d29b80c30d453dda86d1a23162d441628f169 /doc/html/ntqguardedptr.html | |
| parent | aaf89d4b48f69c9293feb187db26362e550b5561 (diff) | |
| download | tqt3-ea318d1431c89e647598c510c4245c6571aa5f46.tar.gz tqt3-ea318d1431c89e647598c510c4245c6571aa5f46.zip | |
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diff --git a/doc/html/ntqguardedptr.html b/doc/html/ntqguardedptr.html new file mode 100644 index 000000000..9d6f85029 --- /dev/null +++ b/doc/html/ntqguardedptr.html @@ -0,0 +1,194 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> +<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/src/kernel/qguardedptr.cpp:40 --> +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> +<title>TQGuardedPtr Class</title> +<style type="text/css"><!-- +fn { margin-left: 1cm; text-indent: -1cm; } +a:link { color: #004faf; text-decoration: none } +a:visited { color: #672967; text-decoration: none } +body { background: #ffffff; color: black; } +--></style> +</head> +<body> + +<table border="0" cellpadding="0" cellspacing="0" width="100%"> +<tr bgcolor="#E5E5E5"> +<td valign=center> + <a href="index.html"> +<font color="#004faf">Home</font></a> + | <a href="classes.html"> +<font color="#004faf">All Classes</font></a> + | <a href="mainclasses.html"> +<font color="#004faf">Main Classes</font></a> + | <a href="annotated.html"> +<font color="#004faf">Annotated</font></a> + | <a href="groups.html"> +<font color="#004faf">Grouped Classes</font></a> + | <a href="functions.html"> +<font color="#004faf">Functions</font></a> +</td> +<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>TQGuardedPtr Class Reference</h1> + +<p>The TQGuardedPtr class is a template class that provides guarded pointers to TQObjects. +<a href="#details">More...</a> +<p><tt>#include <<a href="qguardedptr-h.html">ntqguardedptr.h</a>></tt> +<p><a href="qguardedptr-members.html">List of all member functions.</a> +<h2>Public Members</h2> +<ul> +<li class=fn><a href="#TQGuardedPtr"><b>TQGuardedPtr</b></a> ()</li> +<li class=fn><a href="#TQGuardedPtr-2"><b>TQGuardedPtr</b></a> ( T * p )</li> +<li class=fn><a href="#TQGuardedPtr-3"><b>TQGuardedPtr</b></a> ( const TQGuardedPtr<T> & p )</li> +<li class=fn><a href="#~TQGuardedPtr"><b>~TQGuardedPtr</b></a> ()</li> +<li class=fn>TQGuardedPtr<T> & <a href="#operator-eq"><b>operator=</b></a> ( const TQGuardedPtr<T> & p )</li> +<li class=fn>TQGuardedPtr<T> & <a href="#operator-eq-2"><b>operator=</b></a> ( T * p )</li> +<li class=fn>bool <a href="#operator-eq-eq"><b>operator==</b></a> ( const TQGuardedPtr<T> & p ) const</li> +<li class=fn>bool <a href="#operator!-eq"><b>operator!=</b></a> ( const TQGuardedPtr<T> & p ) const</li> +<li class=fn>bool <a href="#isNull"><b>isNull</b></a> () const</li> +<li class=fn>T * <a href="#operator--gt"><b>operator-></b></a> () const</li> +<li class=fn>T & <a href="#operator*"><b>operator*</b></a> () const</li> +<li class=fn><a href="#operator-T-*"><b>operator T *</b></a> () const</li> +</ul> +<hr><a name="details"></a><h2>Detailed Description</h2> + + +The TQGuardedPtr class is a template class that provides guarded pointers to TQObjects. +<p> + +<p> A guarded pointer, <tt>TQGuardedPtr<X></tt>, behaves like a normal C++ +pointer <tt>X*</tt>, except that it is automatically set to 0 when +the referenced object is destroyed (unlike normal C++ pointers, +which become "dangling pointers" in such cases). <tt>X</tt> must be a +subclass of <a href="ntqobject.html">TQObject</a>. +<p> Guarded pointers are useful whenever you need to store a pointer +to a TQObject that is owned by someone else and therefore might be +destroyed while you still hold a reference to it. You can safely +test the pointer for validity. +<p> Example: +<pre> + TQGuardedPtr<TQLabel> label = new <a href="ntqlabel.html">TQLabel</a>( 0, "label" ); + label->setText( "I like guarded pointers" ); + + delete (TQLabel*) label; // simulate somebody destroying the label + + if ( label) + label->show(); + else + <a href="ntqapplication.html#qDebug">qDebug</a>("The label has been destroyed"); + </pre> + +<p> The program will output <tt>The label has been destroyed</tt> rather +than dereferencing an invalid address in <tt>label->show()</tt>. +<p> The functions and operators available with a TQGuardedPtr are the +same as those available with a normal unguarded pointer, except +the pointer arithmetic operators (++, --, -, and +), which are +normally used only with arrays of objects. Use them like normal +pointers and you will not need to read this class documentation. +<p> For creating guarded pointers, you can construct or assign to them +from an X* or from another guarded pointer of the same type. You +can compare them with each other using <a href="#operator-eq-eq">operator==</a>() and +<a href="#operator!-eq">operator!=</a>(), or test for 0 with <a href="#isNull">isNull</a>(). And you can dereference +them using either the <tt>*x</tt> or the <tt>x->member</tt> notation. +<p> A guarded pointer will automatically cast to an X*, so you can +freely mix guarded and unguarded pointers. This means that if you +have a TQGuardedPtr<TQWidget>, you can pass it to a function that +requires a <a href="ntqwidget.html">TQWidget</a>*. For this reason, it is of little value to +declare functions to take a TQGuardedPtr as a parameter; just use +normal pointers. Use a TQGuardedPtr when you are storing a pointer +over time. +<p> Note again that class <em>X</em> must inherit <a href="ntqobject.html">TQObject</a>, or a compilation +or link error will result. +<p>See also <a href="objectmodel.html">Object Model</a>. + +<hr><h2>Member Function Documentation</h2> +<h3 class=fn><a name="TQGuardedPtr"></a>TQGuardedPtr::TQGuardedPtr () +</h3> + +<p> Constructs a 0 guarded pointer. +<p> <p>See also <a href="#isNull">isNull</a>(). + +<h3 class=fn><a name="TQGuardedPtr-2"></a>TQGuardedPtr::TQGuardedPtr ( T * p ) +</h3> + +<p> Constructs a guarded pointer that points to same object as <em>p</em> +points to. + +<h3 class=fn><a name="TQGuardedPtr-3"></a>TQGuardedPtr::TQGuardedPtr ( const <a href="ntqguardedptr.html">TQGuardedPtr</a><T> & p ) +</h3> + +<p> Copy one guarded pointer from another. The constructed guarded +pointer points to the same object that <em>p</em> points to (which may +be 0). + +<h3 class=fn><a name="~TQGuardedPtr"></a>TQGuardedPtr::~TQGuardedPtr () +</h3> + +<p> Destroys the guarded pointer. Just like a normal pointer, +destroying a guarded pointer does <em>not</em> destroy the object being +pointed to. + +<h3 class=fn>bool <a name="isNull"></a>TQGuardedPtr::isNull () const +</h3> + +<p> Returns <tt>TRUE</tt> if the referenced object has been destroyed or if +there is no referenced object; otherwise returns FALSE. + +<h3 class=fn><a name="operator-T-*"></a>TQGuardedPtr::operator T * () const +</h3> + +<p> Cast operator; implements pointer semantics. Because of this +function you can pass a TQGuardedPtr<X> to a function where an X* +is required. + +<h3 class=fn>bool <a name="operator!-eq"></a>TQGuardedPtr::operator!= ( const <a href="ntqguardedptr.html">TQGuardedPtr</a><T> & p ) const +</h3> + +<p> Inequality operator; implements pointer semantics, the negation of +<a href="#operator-eq-eq">operator==</a>(). Returns TRUE if <em>p</em> and this guarded pointer are +not pointing to the same object; otherwise returns FALSE. + +<h3 class=fn>T & <a name="operator*"></a>TQGuardedPtr::operator* () const +</h3> + +<p> Dereference operator; implements pointer semantics. Just use this +operator as you would with a normal C++ pointer. + +<h3 class=fn>T * <a name="operator--gt"></a>TQGuardedPtr::operator-> () const +</h3> + +<p> Overloaded arrow operator; implements pointer semantics. Just use +this operator as you would with a normal C++ pointer. + +<h3 class=fn><a href="ntqguardedptr.html">TQGuardedPtr</a><T> & <a name="operator-eq"></a>TQGuardedPtr::operator= ( const <a href="ntqguardedptr.html">TQGuardedPtr</a><T> & p ) +</h3> + +<p> Assignment operator. This guarded pointer then points to the same +object as <em>p</em> points to. + +<h3 class=fn><a href="ntqguardedptr.html">TQGuardedPtr</a><T> & <a name="operator-eq-2"></a>TQGuardedPtr::operator= ( T * p ) +</h3> +This is an overloaded member function, provided for convenience. It behaves essentially like the above function. +<p> Assignment operator. This guarded pointer then points to the same +object as <em>p</em> points to. + +<h3 class=fn>bool <a name="operator-eq-eq"></a>TQGuardedPtr::operator== ( const <a href="ntqguardedptr.html">TQGuardedPtr</a><T> & p ) const +</h3> + +<p> Equality operator; implements traditional pointer semantics. +Returns TRUE if both <em>p</em> and this guarded pointer are 0, or if +both <em>p</em> and this pointer point to the same object; otherwise +returns FALSE. +<p> <p>See also <a href="#operator!-eq">operator!=</a>(). + +<!-- eof --> +<hr><p> +This file is part of the <a href="index.html">TQt toolkit</a>. +Copyright © 1995-2007 +<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center> +<table width=100% cellspacing=0 border=0><tr> +<td>Copyright © 2007 +<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a> +<td align=right><div align=right>TQt 3.3.8</div> +</table></div></address></body> +</html> |