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<td width="885"> <font face="Verdana, Arial, Helvetica, sans-serif"><b><font size="6">Supported
Pragma Directives</font></b></font></td>
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<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>
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<td colspan="3"> <p class="table_title">Supported pragma's</p></td>
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<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>
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<td class="table_cells" width="20%"> <p>trace</p></td>
<td class="table_cells" width="17%"> <p>enable/disable<br>
1/0</p></td>
<td class="table_cells" width="63%"><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>
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<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>
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<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>
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<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>
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<p class="copyright">Copyright © 2003 Hartmut Kaiser<br>
<br>
<font size="2">Permission to copy, use, modify, sell and distribute this document
is granted provided this copyright notice appears in all copies. This document
is provided "as is" without express or implied warranty, and with
no claim as to its suitability for any purpose. </font> </p>
<span class="updated">Last updated:
<!-- #BeginDate format:fcAm1m -->Tuesday, April 29, 2003 19:58<!-- #EndDate -->
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