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Updated example for using the BOOST_PP_VARIADIC_OPT macro.

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Edward Diener
2019-09-26 01:19:31 -04:00
parent 0cdd09e6e1
commit a42f374b97
1 changed files with 14 additions and 5 deletions
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19
doc/ref/variadic_opt.html
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@ -23,11 +23,20 @@ Expands to 1 if the __VA_OPT__ construct is supported, otherwise expands to 0.
<div> <div>
<pre> <pre>
#include &lt;<a href="../headers/variadic/opt.html">boost/preprocessor/variadic/opt.hpp</a>&gt;<br> #include &lt;<a href="../headers/variadic/opt.html">boost/preprocessor/variadic/opt.hpp</a>&gt;<br>
#if <a href="variadic_opt.html">BOOST_PP_VARIADIC_OPT</a>()<br> #if <a href="variadic_opt.html">BOOST_PP_VARIADIC_OPT</a>()
// Preprocessor code which uses __VA_OPT__<br> // Preprocessor code which uses __VA_OPT__
#else<br> #else
// Preprocessor code which does not use __VA_OPT__<br> // Preprocessor code which does not use __VA_OPT__
#endif<br> #endif
</pre>
<br>
or within a macro definition<br><br>
<pre>
#include &lt;boost/preprocessor/control/iif.hpp&gt;
#include &lt;<a href="../headers/variadic/opt.html">boost/preprocessor/variadic/opt.hpp</a>&gt;<br>
#define USE_OPT(...) BOOST_PP_IIF(<a href="variadic_opt.html">BOOST_PP_VARIADIC_OPT</a>(),MACRO_USING_OPT,MACRO_NOT_USING_OPT)(__VA_ARGS__)
#define MACRO_USING_OPT(...) __VA_OPT__( preprocessor tokens ) anything
#define MACRO_NOT_USING_OPT(...) anything
</pre> </pre>
</div> </div>
<hr size="1"> <hr size="1">