1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Visual C++ gotchas in VMD</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. The Variadic Macro Data Library 1.9"> 8<link rel="up" href="../index.html" title="Chapter 1. The Variadic Macro Data Library 1.9"> 9<link rel="prev" href="vmd_dynamic_typing.html" title="Input as dynamic types"> 10<link rel="next" href="vmd_conv.html" title="Version 1.7 to 1.8 conversion"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="vmd_dynamic_typing.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="vmd_conv.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h2 class="title" style="clear: both"> 27<a name="variadic_macro_data.vmd_vc_isms"></a><a class="link" href="vmd_vc_isms.html" title="Visual C++ gotchas in VMD">Visual C++ gotchas in 28 VMD</a> 29</h2></div></div></div> 30<p> 31 I have discussed throughout the documentation areas of VMD which need to be 32 considered when using Microsoft's Visual C++ compilers. The VMD library supports 33 VC++ versions 8 through the latest 14.2. These correspond to Visual Studio 34 2005 through the current Visual Studio 2019. 35 </p> 36<p> 37 I will give here fairly briefly the VC++ quirks which should be taken into 38 account when using VMD. These quirks exist because the VC++ compiler does not 39 have a C++ standard conforming preprocessor. More specifically the VC++ compiler 40 does not follow all of the rules correctly for expanding a macro when a macro 41 is invoked. Here is a list for things to consider when using VMD with VC++: 42 </p> 43<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 44<li class="listitem"> 45 The BOOST_VMD_IS_EMPTY macro will expand erroneously to 1 if the input 46 resolves to a function-like macro name, which when it is called with an 47 empty parameter expands to a tuple. 48 </li> 49<li class="listitem"> 50 The BOOST_VMD_ASSERT macro, and the corresponding individual VMD ASSERT 51 macros for the various data types, do not cause an immediate compiler error, 52 but instead generate invalid C++ if the ASSERT occurs. 53 </li> 54<li class="listitem"> 55 When the BOOST_VMD_ASSERT macro, or one of the corresponding individual 56 VMD ASSERT macros for the various data types, does not generate an error, 57 and the macro in which it is being used does generate some output, it is 58 necessary to use BOOST_PP_CAT to concatenate the empty result of the VMD 59 ASSERT macro with the normally generated output to correctly generate the 60 final expansion of the macro in which the VMD ASSERT occurs. 61 </li> 62<li class="listitem"> 63 When using BOOST_VMD_EMPTY following some non-empty expansion, or when 64 using BOOST_VMD_IDENTITY, the value returned needs to be concatenated using 65 BOOST_PP_CAT with an empty value. You can use BOOST_VMD_IDENTITY_RESULT 66 to accomplish this transparently. 67 </li> 68<li class="listitem"> 69 Avoid using an empty parenthesis to pass no data as a tuple or seq if VC++8 70 might be used as the compiler. 71 </li> 72</ul></div> 73</div> 74<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 75<td align="left"></td> 76<td align="right"><div class="copyright-footer">Copyright © 2010-2017 Tropic Software 77 East Inc</div></td> 78</tr></table> 79<hr> 80<div class="spirit-nav"> 81<a accesskey="p" href="vmd_dynamic_typing.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="vmd_conv.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 82</div> 83</body> 84</html> 85
