ceph/src/boost/libs/statechart/doc/configuration.html

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  11   <title>The Boost Statechart Library - Configuration</title>
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  24         <h1 align="center">The Boost Statechart Library</h1>
  25
  26         <h2 align="center">Configuration</h2>
  27       </td>
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  29   </table>
  30   <hr>
  31
  32   <dl class="page-index">
  33     <dt><a href="#GeneralConfiguration">General configuration</a></dt>
  34
  35     <dd><a href="#Introduction">Introduction</a></dd>
  36
  37     <dd><a href="#DebugModeCompilationOptions">Debug mode compilation
  38     options</a></dd>
  39
  40     <dd><a href="#ReleaseModeCompilationOptions">Release mode compilation
  41     options</a></dd>
  42
  43     <dd><a href="#ApplicationDefinedMacros">Application Defined
  44     Macros</a></dd>
  45   </dl>
  46
  47   <h1><a id="GeneralConfiguration" name="GeneralConfiguration">General
  48   configuration</a></h1>
  49
  50   <h2><a id="Introduction" name="Introduction">Introduction</a></h2>
  51
  52   <p>The library uses several configuration macros in <a href=
  53   "../../../libs/config/config.htm">&lt;boost/config.hpp&gt;</a>, as well as
  54   two configuration macros meant to be supplied by the application. Moreover,
  55   two commonly available compiler options also have an impact on the
  56   available features.</p>
  57
  58   <h2><a id="DebugModeCompilationOptions" name=
  59   "DebugModeCompilationOptions">Debug mode compilation options</a></h2>
  60
  61   <ul>
  62     <li>C++ RTTI must be turned on (used by various asserts)</li>
  63
  64     <li>C++ exception handling can be turned on or off. When turned off,
  65     obviously the library's <a href="tutorial.html#ExceptionHandling">error
  66     handling support</a> is no longer available</li>
  67   </ul>
  68
  69   <h2><a id="ReleaseModeCompilationOptions" name=
  70   "ReleaseModeCompilationOptions">Release mode compilation options</a></h2>
  71
  72   <ul>
  73     <li>C++ RTTI can be turned on or off. When turned off, the use of
  74     <code><a href="reference.html#state_cast">state_cast&lt;&gt;()</a></code>
  75     leads to a compile time error (<code><a href=
  76     "reference.html#state_downcast">state_downcast&lt;&gt;()</a></code> is
  77     still available). Moreover, <code>BOOST_STATECHART_USE_NATIVE_RTTI</code>
  78     must not be defined simultaneously</li>
  79
  80     <li>C++ exception handling can be turned on or off. When turned off,
  81     obviously the library's <a href="tutorial.html#ExceptionHandling">error
  82     handling support</a> is no longer available</li>
  83   </ul>
  84
  85   <h2><a id="ApplicationDefinedMacros" name=
  86   "ApplicationDefinedMacros">Application Defined Macros</a></h2>
  87
  88   <p>The following macros may be defined by an application using the
  89   library:</p>
  90
  91   <table summary="application defined macros" width="100%" cellpadding="2"
  92   border="3">
  93     <tr>
  94       <td width="226"><b>Macro</b></td>
  95
  96       <td width="893"><b>Meaning</b></td>
  97     </tr>
  98
  99     <tr>
 100       <td width="226"><code>BOOST_STATECHART_USE_NATIVE_RTTI</code></td>
 101
 102       <td width="893">
 103         When defined, the library no longer uses its own speed-optimized RTTI
 104         implementation. Instead, native C++ RTTI is employed (see <a href=
 105         "performance.html#RttiCustomization">RTTI customization</a> in the
 106         performance document for more information). This has the following
 107         effects:
 108
 109         <ul>
 110           <li><code>state_machine::state_base_type</code> becomes a
 111           polymorphic type. That is, when <code>typeid</code> is applied to a
 112           <code>state_machine::state_base_type</code> reference, the result
 113           refers to a <code>type_info</code> object representing the the type
 114           of the most derived state type</li>
 115
 116           <li><a href="tutorial.html#CustomStateTypeInformation">Custom state
 117           type information</a> is no longer available</li>
 118
 119           <li>All states need to store one pointer less, leading to a
 120           best-case state machine memory footprint reduction of about
 121           15%</li>
 122
 123           <li>Under most circumstances, dispatch speed degrades. This is
 124           because native C++ RTTI values are retrieved through an additional
 125           indirection on almost all platforms. See <a href=
 126           "performance.html#SpeedVersusScalabilityTradeoffs">Speed versus
 127           scalability tradeoffs</a> in the performance document for
 128           timings</li>
 129         </ul>
 130       </td>
 131     </tr>
 132
 133     <tr>
 134       <td width="226">
 135       <code>BOOST_STATECHART_RELAX_TRANSITION_CONTEXT</code></td>
 136
 137       <td width="893">When defined, the sequence of actions that are called
 138       during a transition is relaxed. That is, its is no longer necessary
 139       that all states up to the innermost common context are exited before
 140       the transition action is called (as mandated by the UML standard).
 141       Instead, the transition action can be a member of either the transition
 142       source or any direct or indirect outer context and is called as soon as
 143       all possibly active inner states have been exited. Then all remaining
 144       active states up to the innermost common context are exited before
 145       entering all states down to the transition destination</td>
 146     </tr>
 147   </table>
 148
 149   <p>Both macros need to be consistently defined or undefined for all
 150   translation units that are later linked into the same executable. Not doing
 151   so will inevitably lead to ODR violations. Depending on compiler and linker
 152   technology such violations may or may not manifest themselves in link-time
 153   errors.</p>
 154
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 158
 159   <p>Revised 05 January, 2008</p>
 160
 161   <p><i>Copyright &copy; 2003-2008 <a href="contact.html">Andreas Huber
 162   D&ouml;nni</a></i></p>
 163
 164   <p><i>Distributed under the Boost Software License, Version 1.0. (See
 165   accompanying file <a href="../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
 166   copy at <a href=
 167   "http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</a>)</i></p>
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