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<a href="#pub-methods">Public Member Functions</a> |
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<div class="title">wxRecursionGuard Class Reference<div class="ingroups"><a class="el" href="group__group__class__misc.html">Miscellaneous</a></div></div> </div>
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<p><code>#include <wx/recguard.h></code></p>
<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
<div class="textblock"><p><a class="el" href="classwx_recursion_guard.html" title="wxRecursionGuard is a very simple class which can be used to prevent reentrancy problems in a functio...">wxRecursionGuard</a> is a very simple class which can be used to prevent reentrancy problems in a function. </p>
<p>It is not thread-safe and so should be used only in single-threaded programs or in combination with some thread synchronization mechanisms.</p>
<p><a class="el" href="classwx_recursion_guard.html" title="wxRecursionGuard is a very simple class which can be used to prevent reentrancy problems in a functio...">wxRecursionGuard</a> is always used together with the <a class="el" href="classwx_recursion_guard_flag.html" title="This is a completely opaque class which exists only to be used with wxRecursionGuard, please see the example in that class' documentation.">wxRecursionGuardFlag</a> like in this example:</p>
<div class="fragment"><div class="line"><span class="keywordtype">void</span> Foo()</div>
<div class="line">{</div>
<div class="line"> <span class="keyword">static</span> <a class="code" href="classwx_recursion_guard_flag.html" title="This is a completely opaque class which exists only to be used with wxRecursionGuard, please see the example in that class' documentation.">wxRecursionGuardFlag</a> s_flag;</div>
<div class="line"> <a class="code" href="classwx_recursion_guard.html" title="wxRecursionGuard is a very simple class which can be used to prevent reentrancy problems in a functio...">wxRecursionGuard</a> guard(s_flag);</div>
<div class="line"> <span class="keywordflow">if</span> ( guard.IsInside() )</div>
<div class="line"> {</div>
<div class="line"> <span class="comment">// don't allow reentrancy</span></div>
<div class="line"> <span class="keywordflow">return</span>;</div>
<div class="line"> }</div>
<div class="line"></div>
<div class="line"> ...</div>
<div class="line">}</div>
</div><!-- fragment --><p>As you can see, <a class="el" href="classwx_recursion_guard.html" title="wxRecursionGuard is a very simple class which can be used to prevent reentrancy problems in a functio...">wxRecursionGuard</a> simply tests the flag value and sets it to <span class="literal">true</span> if it hadn't been already set. <a class="el" href="classwx_recursion_guard.html#a82df654ab0277174eef32eae3bcd02d1" title="Returns true if we're already inside the code block "protected" by this wxRecursionGuard (i...">IsInside()</a> allows testing the old flag value. The advantage of using this class compared to directly manipulating the flag is that the flag is always reset in the <a class="el" href="classwx_recursion_guard.html" title="wxRecursionGuard is a very simple class which can be used to prevent reentrancy problems in a functio...">wxRecursionGuard</a> destructor and so you don't risk to forget to do it even if the function returns in an unexpected way (for example because an exception has been thrown).</p>
<h2></h2>
<div><span class="lib">Library:</span>  <span class="lib_text"><a class="el" href="page_libs.html#page_libs_wxbase">wxBase</a></span></div><div><span class="category">Category:</span>  <span class="category_text"><a class="el" href="group__group__class__misc.html">Miscellaneous</a></span></div> </div><table class="memberdecls">
<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="pub-methods"></a>
Public Member Functions</h2></td></tr>
<tr class="memitem:a9dde9c6284b26edda237c219eff09145"><td class="memItemLeft" align="right" valign="top"> </td><td class="memItemRight" valign="bottom"><a class="el" href="classwx_recursion_guard.html#a9dde9c6284b26edda237c219eff09145">wxRecursionGuard</a> (<a class="el" href="classwx_recursion_guard_flag.html">wxRecursionGuardFlag</a> &flag)</td></tr>
<tr class="memdesc:a9dde9c6284b26edda237c219eff09145"><td class="mdescLeft"> </td><td class="mdescRight">A <a class="el" href="classwx_recursion_guard.html" title="wxRecursionGuard is a very simple class which can be used to prevent reentrancy problems in a functio...">wxRecursionGuard</a> object must always be initialized with a <code>static</code> <a class="el" href="classwx_recursion_guard_flag.html" title="This is a completely opaque class which exists only to be used with wxRecursionGuard, please see the example in that class' documentation.">wxRecursionGuardFlag</a>. <a href="#a9dde9c6284b26edda237c219eff09145"></a><br/></td></tr>
<tr class="separator:a9dde9c6284b26edda237c219eff09145"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:adeb06fb439b4529d96f3e45544a27187"><td class="memItemLeft" align="right" valign="top"> </td><td class="memItemRight" valign="bottom"><a class="el" href="classwx_recursion_guard.html#adeb06fb439b4529d96f3e45544a27187">~wxRecursionGuard</a> ()</td></tr>
<tr class="memdesc:adeb06fb439b4529d96f3e45544a27187"><td class="mdescLeft"> </td><td class="mdescRight">The destructor resets the flag value so that the function can be entered again the next time. <a href="#adeb06fb439b4529d96f3e45544a27187"></a><br/></td></tr>
<tr class="separator:adeb06fb439b4529d96f3e45544a27187"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:a82df654ab0277174eef32eae3bcd02d1"><td class="memItemLeft" align="right" valign="top">bool </td><td class="memItemRight" valign="bottom"><a class="el" href="classwx_recursion_guard.html#a82df654ab0277174eef32eae3bcd02d1">IsInside</a> () const </td></tr>
<tr class="memdesc:a82df654ab0277174eef32eae3bcd02d1"><td class="mdescLeft"> </td><td class="mdescRight">Returns <span class="literal">true</span> if we're already inside the code block "protected" by this <a class="el" href="classwx_recursion_guard.html" title="wxRecursionGuard is a very simple class which can be used to prevent reentrancy problems in a functio...">wxRecursionGuard</a> (i.e. <a href="#a82df654ab0277174eef32eae3bcd02d1"></a><br/></td></tr>
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<h2 class="groupheader">Constructor & Destructor Documentation</h2>
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<td class="memname">wxRecursionGuard::wxRecursionGuard </td>
<td>(</td>
<td class="paramtype"><a class="el" href="classwx_recursion_guard_flag.html">wxRecursionGuardFlag</a> & </td>
<td class="paramname"><em>flag</em></td><td>)</td>
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<p>A <a class="el" href="classwx_recursion_guard.html" title="wxRecursionGuard is a very simple class which can be used to prevent reentrancy problems in a functio...">wxRecursionGuard</a> object must always be initialized with a <code>static</code> <a class="el" href="classwx_recursion_guard_flag.html" title="This is a completely opaque class which exists only to be used with wxRecursionGuard, please see the example in that class' documentation.">wxRecursionGuardFlag</a>. </p>
<p>The constructor saves the value of the flag to be able to return the correct value from <a class="el" href="classwx_recursion_guard.html#a82df654ab0277174eef32eae3bcd02d1" title="Returns true if we're already inside the code block "protected" by this wxRecursionGuard (i...">IsInside()</a>. </p>
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<td class="memname">wxRecursionGuard::~wxRecursionGuard </td>
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<p>The destructor resets the flag value so that the function can be entered again the next time. </p>
<dl class="section note"><dt>Note</dt><dd>This is not virtual, so this class is not meant to be derived from (besides, there is absolutely no reason to do it anyhow). </dd></dl>
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<h2 class="groupheader">Member Function Documentation</h2>
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<td class="memname">bool wxRecursionGuard::IsInside </td>
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<td class="paramname"></td><td>)</td>
<td> const</td>
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<p>Returns <span class="literal">true</span> if we're already inside the code block "protected" by this <a class="el" href="classwx_recursion_guard.html" title="wxRecursionGuard is a very simple class which can be used to prevent reentrancy problems in a functio...">wxRecursionGuard</a> (i.e. </p>
<p>between this line and the end of current scope). Usually the function using <a class="el" href="classwx_recursion_guard.html" title="wxRecursionGuard is a very simple class which can be used to prevent reentrancy problems in a functio...">wxRecursionGuard</a> takes some specific actions in such case (may be simply returning) to prevent reentrant calls to itself.</p>
<p>If this method returns <span class="literal">false</span>, it is safe to continue. </p>
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