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<div class="title">Query information from <a class="el" href="classrttr_1_1type.html" title="The type class holds the type information for any arbitrary object.">rttr::type</a> </div> </div>
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<div class="textblock"><p>A <a class="el" href="classrttr_1_1type.html">type</a> object contains automatically a lot of useful meta information, which exceeds the information of the standard <a href="http://en.cppreference.com/w/cpp/types/type_info" target="_blank">type_info</a> object.</p>
<div class="fragment"><div class="line"><span class="keyword">struct </span>D { ... };</div><div class="line"></div><div class="line">type::get<D>().get_name(); <span class="comment">// returns 'struct D'; remark this is a compiler specific defined string (not portable)</span></div><div class="line">type::get<D>().is_class(); <span class="comment">// true</span></div><div class="line">type::get<D>().is_pointer(); <span class="comment">// false</span></div><div class="line">type::get<D*>().is_pointer(); <span class="comment">// true</span></div><div class="line">type::get<D>().is_array(); <span class="comment">// false</span></div><div class="line">type::get<D[50]>().is_array(); <span class="comment">// true</span></div><div class="line">type::get<std::vector<D>>().is_array(); <span class="comment">// true</span></div><div class="line">type::get<D>().is_arithmetic(); <span class="comment">// false</span></div><div class="line">type::get<D>().is_enumeration(); <span class="comment">// false</span></div></div><!-- fragment --><p>The returned name of the function <a class="el" href="classrttr_1_1type.html#a16d519457c68429ef2316067d1cf6700">get_name()</a> returns a compiler depended string. So don't use it directly when comparing with a string literal, but it is very useful for debugging purposes.</p>
<p>This functionality gets more useful when working with other components like <a class="el" href="classrttr_1_1property.html">properties</a> or <a class="el" href="classrttr_1_1variant.html">variants</a>. For example: when you iterate over all properties of class you might not want to store the values of pointer types. Or you might want to group stuff together, like: <em>give me all primitive properties of a class</em> and so on.</p>
<p>It is also possible to retrieve information about the inheritance graph of a class. </p><div class="fragment"><div class="line"><span class="keyword">struct </span>Base { <a class="code" href="rttr__enable_8h.html#a848bcae21d3a54e07ca6450689820a59">RTTR_ENABLE</a>() };</div><div class="line"><span class="keyword">struct </span>Derived : Base { <a class="code" href="rttr__enable_8h.html#a848bcae21d3a54e07ca6450689820a59">RTTR_ENABLE</a>(Base) };</div><div class="line"></div><div class="line">Derived d;</div><div class="line"></div><div class="line">std::vector<type> base_list = type::get(d).get_base_classes();</div><div class="line"></div><div class="line"><span class="keywordflow">for</span> (<span class="keyword">auto</span>& t : base_list)</div><div class="line"> std::cout << t.get_name() << std::endl; <span class="comment">// 'struct Base'</span></div></div><!-- fragment --><p>Or use a shorthand method to check if a type is derived from another:</p>
<div class="fragment"><div class="line">type::get(d).is_derived_from<Base>(); <span class="comment">// true</span></div></div><!-- fragment --><p>The meta information presented in the first code snipped (e.g. <a class="el" href="classrttr_1_1type.html#a34296e0290e93317c34118945c0e2db9">is_class()</a>, <a class="el" href="classrttr_1_1type.html#a24a00513155d3e678454aa349b0caaa7">is_pointer()</a>) will work without registering anything manually to the type system. In order to retrieve class hierarchy informations, like <a class="el" href="classrttr_1_1type.html#aed9b001581881e62aaf794f456e405e7">get_base_classes()</a> or <a class="el" href="classrttr_1_1type.html#ac8484b0779404e55c3116ea5a1b894fa">is_derived_from()</a>, you will have to add manually some information to the type system. How this will be done, is discussed in the <a class="el" href="rttr_type_class_hierachy_page.html">next</a> chapter.</p>
<h2>Summary </h2>
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<li>with a <a class="el" href="classrttr_1_1type.html">type</a> object you can retrieve additional meta information at runtime</li>
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