1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Macro BOOST_VMD_ASSERT_IS_IDENTIFIER</title> 5<link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="index.html" title="Chapter 1. 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If it is not an identifier, it forces a compiler error.</p> 38<p>The macro normally checks for an identifier only in debug mode. However an end-user can force the macro to check or not check by defining the macro BOOST_VMD_ASSERT_DATA to 1 or 0 respectively.</p> 39<p>... = variadic parameters</p> 40<p>The variadic parameters are:</p> 41<p>sequence = A sequence to test as an identifier. <br> 42 ids (optional) = The data may take one of two forms: it is either one or more single identifiers or a single Boost PP tuple of identifiers.</p> 43<pre class="programlisting"><span class="identifier">returns</span> <span class="special">=</span> <span class="identifier">Normally</span> <span class="identifier">the</span> <span class="identifier">macro</span> <span class="identifier">returns</span> <span class="identifier">nothing</span><span class="special">.</span> 44 45 <span class="identifier">If</span> <span class="identifier">the</span> <span class="identifier">sequence</span> <span class="identifier">is</span> <span class="identifier">an</span> <span class="identifier">identifier</span><span class="special">,</span> <span class="identifier">nothing</span> <span class="identifier">is</span> 46 <span class="identifier">output</span><span class="special">.</span> <span class="identifier">If</span> <span class="identifier">optional</span> <span class="identifier">ids</span> <span class="identifier">are</span> <span class="identifier">specified</span><span class="special">,</span> <span class="keyword">for</span> <span class="identifier">the</span> 47 <span class="identifier">sequence</span> <span class="identifier">to</span> <span class="identifier">be</span> <span class="identifier">an</span> <span class="identifier">identifier</span> <span class="identifier">it</span> <span class="identifier">must</span> <span class="identifier">be</span> <span class="identifier">an</span> 48 <span class="identifier">identifier</span> <span class="identifier">that</span> <span class="identifier">matches</span> <span class="identifier">one</span> <span class="identifier">of</span> <span class="identifier">the</span> <span class="identifier">optional</span> 49 <span class="identifier">ids</span><span class="special">.</span> 50 51 <span class="identifier">For</span> <span class="identifier">VC</span><span class="special">++</span><span class="special">,</span> <span class="identifier">because</span> <span class="identifier">there</span> <span class="identifier">is</span> <span class="identifier">no</span> <span class="identifier">sure</span> <span class="identifier">way</span> <span class="identifier">of</span> <span class="identifier">forcing</span> 52 <span class="identifier">a</span> <span class="identifier">compiler</span> <span class="identifier">error</span> <span class="identifier">from</span> <span class="identifier">within</span> <span class="identifier">a</span> <span class="identifier">macro</span> <span class="identifier">without</span> <span class="identifier">producing</span> 53 <span class="identifier">output</span><span class="special">,</span> <span class="keyword">if</span> <span class="identifier">the</span> <span class="identifier">sequence</span> <span class="identifier">is</span> <span class="identifier">not</span> <span class="identifier">an</span> <span class="identifier">identifier</span> <span class="identifier">the</span> 54 <span class="identifier">macro</span> <span class="identifier">forces</span> <span class="identifier">a</span> <span class="identifier">compiler</span> <span class="identifier">error</span> <span class="identifier">by</span> <span class="identifier">outputting</span> <span class="identifier">invalid</span> <span class="identifier">C</span><span class="special">++</span><span class="special">.</span> 55 56 <span class="identifier">For</span> <span class="identifier">all</span> <span class="identifier">other</span> <span class="identifier">compilers</span> <span class="identifier">a</span> <span class="identifier">compiler</span> <span class="identifier">error</span> <span class="identifier">is</span> <span class="identifier">forced</span> 57 <span class="identifier">without</span> <span class="identifier">producing</span> <span class="identifier">output</span> <span class="keyword">if</span> <span class="identifier">the</span> <span class="identifier">sequence</span> <span class="identifier">is</span> <span class="identifier">not</span> <span class="identifier">an</span> 58 <span class="identifier">identifier</span><span class="special">.</span> 59</pre> 60<p>Identifiers are registered in VMD with:</p> 61<pre class="programlisting"><span class="preprocessor">#define</span> <span class="identifier">BOOST_VMD_REG_XXX</span> <span class="special">(</span><span class="identifier">XXX</span><span class="special">)</span> <span class="identifier">where</span> <span class="identifier">XXX</span> <span class="identifier">is</span> <span class="identifier">a</span> <span class="identifier">v</span><span class="special">-</span><span class="identifier">identifier</span><span class="special">.</span> 62</pre> 63<p>The identifier must be registered to be found.</p> 64<p>Identifiers are pre-detected in VMD with:</p> 65<pre class="programlisting"><span class="preprocessor">#define</span> <span class="identifier">BOOST_VMD_DETECT_XXX_XXX</span> <span class="identifier">where</span> <span class="identifier">XXX</span> <span class="identifier">is</span> <span class="identifier">an</span> <span class="identifier">identifier</span><span class="special">.</span> 66</pre> 67<p>If you specify optional ids and have not specified the detection of an optional id, that id will never match an identifier. </p> 68</div> 69</div> 70<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 71<td align="left"></td> 72<td align="right"><div class="copyright-footer">Copyright © 2010-2017 Tropic Software 73 East Inc</div></td> 74</tr></table> 75<hr> 76<div class="spirit-nav"> 77<a accesskey="p" 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