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<title>Apache Qpid : NoUsingNamespaceInHeaders</title>
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Apache Qpid : NoUsingNamespaceInHeaders
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This page last changed on Oct 19, 2006 by <font color="#0050B2">mmccorma</font>.
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<p>Don't use the{{using namespace ...}} or <tt>using ...</tt> constructs in a header file. It might save you some typing but it also forces the namespaces you use onto every <tt>.cpp</tt> file that directly or indirectly includes your headers. That could create name clashes with names in some other namespace that the author of the <tt>.cpp</tt> file wants to use. Use fully qualified names, painful as it might be.</p>
<p>There is one exception. It's sometimes handy to "import" names from one namespace to another. For example suppose some C++ compiler doesn't provide the <tt>std::tr1::auto_ptr</tt> template, which is used in qpid. <a href="http://www.boost.org" title="Visit page outside Confluence">Boost</a> does provide a compatible <tt>boost::auto_ptr</tt> but it's in the boost namespace and qpid expects it in <tt>std::tr1</tt>. No problem, we create our own tr1/memory header file:</p>
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<pre class="code-java">#include <boost/memory>
namespace std {
namespace tr1 {
using boost::auto_ptr;
}
}</pre>
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<p>This makes the boost template available in the standard namespace. (Actually you don't need to do this yourself, boost provides a set of adapter headers for all the tr1 stuff.)</p>
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<td align="center"><font color="grey">Document generated by Confluence on Apr 22, 2008 02:47</font></td>
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