<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Supported Pragma Directives</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<link href="theme/style.css" rel="stylesheet" type="text/css">
</head>
<body>
<table width="100%" border="0" cellspacing="2" background="theme/bkd2.gif">
<tr>
<td width="21"> <h1></h1></td>
<td width="885"> <font face="Verdana, Arial, Helvetica, sans-serif"><b><font size="6">Supported
Pragma Directives</font></b></font></td>
<td width="96"><a href="http://spirit.sf.net"><img src="theme/wave.gif" width="93" height="68" align="right" border="0"></a></td>
</tr>
</table>
<br>
<table border="0">
<tr>
<td width="10"></td>
<td width="30"><a href="index.html"><img src="theme/u_arr.gif" border="0"></a></td>
<td width="30"><a href="predefined_macros.html"><img src="theme/l_arr.gif" border="0"></a></td>
<td width="30"><a href="macro_expansion_process.html"><img src="theme/r_arr.gif" border="0"></a></td>
</tr>
</table>
<p>The Wave preprocessor library supports a couple of specific <tt>#pragma</tt>
directives, which may be used to control some of the library features. All directives
described here are usable as conventional <tt>#pragma</tt> directives and as
<tt>operator _Pragma</tt> (if variadics are enabled). So for instance the
following directives are functionally identical:</p>
<pre> #pragma wave trace(enable) </pre>
<p>and </p>
<pre> _Pragma("wave trace(enable)")</pre>
<p>All <tt>Wave</tt> specific pragma's must have the general form <tt>'wave option[(value)]'</tt>,
where <tt>'wave'</tt> is the specific keyword, <tt>'option'</tt> is the concrete
pragma functionality to trigger and <tt>'value'</tt> is an optional value to
be supplied to the <tt>'option'</tt> functionality. The following table lists
all possible pragma functions supported by the <tt>Wave</tt> library. </p>
<table width="77%" border="0" align="center">
<tr>
<td colspan="4"> <p class="table_title">Supported pragma's</p></td>
</tr>
<tr>
<td> <p class="toc_title" width="36%">pragma option</p></td>
<td> <p class="toc_title" width="28%">pragma value</p></td>
<td> <p class="toc_title" width="36%">description</p></td>
<td> <p class="toc_title" width="36%">supported by</p></td>
</tr>
<tr>
<td class="table_cells" width="19%"> <p>trace</p></td>
<td class="table_cells" width="18%"> <p>enable/on/1<br>
disable/off/0</p></td>
<td class="table_cells" width="43%"><p>Enable or disable the tracing of the
macro expansion process. This is needed, even if there is given the --trace
command line option, because the trace output is generated only, if there
is at least one trace(enable) pragma found.</p></td>
<td class="table_cells" width="20%"><p>Wave library</p></td>
</tr>
<tr>
<td class="table_cells"><p>stop</p></td>
<td class="table_cells"><p>message</p></td>
<td class="table_cells"><p>Stop the execution of <tt>Wave</tt> and print out
the given message. This is very helpful for direct debugging purposes.</p></td>
<td class="table_cells"><p>Wave library</p></td>
</tr>
<tr>
<td class="table_cells"><p>system</p></td>
<td class="table_cells"><p>command</p></td>
<td class="table_cells"><p>Try to spawn the 'command' as a new operating system
command and intercept the generated stdout and stderr. The stdout output
of this command (if any) is retokenized and used as the replacement text
for the whole pragma, the stderr output is ignored. The command is considered
to be successful, if/when the return value is zero, otherwise an error
is reported. <br>
</p></td>
<td class="table_cells"><p>Wave library</p></td>
</tr>
<tr>
<td class="table_cells"><p>timer</p></td>
<td class="table_cells"><p> restart/0<br>
<no value> <br>
suspend<br>
resume </p></td>
<td class="table_cells"><p>The value <tt>restart</tt> set the current elapsed
time to 0 and restarts the timer.<br>
If no value is provided, the current elpsed time is printed to the std::cerr
stream.<br>
The values <tt>suspend</tt> and <tt>resume</tt> allow to temporarily stop
the timing.</p></td>
<td class="table_cells"><p>Wave driver</p></td>
</tr>
</table>
<p>All pragma's not listed here but flagged as <tt>'wave'</tt> are reported as
errors. The handling of all remaining pragma's depends on the compilation constant
<code><tt>WAVE_RETURN_PRAGMA_DIRECTIVES</tt></code>, which allows to specify,
if those pragmas are left unchanged in the output stream or not. Please note,
that the operator _Pragma variant is always subject to full preprocessing, before
the pragma itself is evaluated. The #pragma variant is subject to preprocessing
only, if the <code><tt>WAVE_PREPROCESS_PRAGMA_BODY</tt></code> compilation constant
was specified during compilation.For more information about the possible compilation
constants look <a href="compiletime_config.html">here</a>.</p>
<p>Additionally the Wave preprocessor supports the <tt>#pragma once</tt> directive,
which specifies that the file, in which the pragma resides, will be included
(opened) only once by the compiler in a build. This may be used to optimize
the preprocessing of larger compilation units, which include a lot of files.</p>
<table border="0">
<tr>
<td width="10"></td>
<td width="30"><a href="./index.html"><img src="theme/u_arr.gif" border="0"></a></td>
<td width="30"><a href="predefined_macros.html"><img src="theme/l_arr.gif" border="0"></a></td>
<td width="30"><a href="macro_expansion_process.html"><img src="theme/r_arr.gif" border="0"></a></td>
</tr>
</table>
<hr size="1">
<p class="copyright">Copyright © 2003-2004 Hartmut Kaiser<br>
<br>
<font size="2">Use, modification and distribution is subject to the Boost Software
License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
</font> </p>
<span class="updated">Last updated:
<!-- #BeginDate format:fcAm1m -->Monday, January 5, 2004 14:57<!-- #EndDate -->
</span>
<p> </p>
</body>
</html>