NumRanges+1&gt;::type  operator[](index idx) const;
};

typedef *implementation_defined*&lt;0&gt; extent_gen;
</pre>
<p><b>Methods and Types.&#160;</b></p>
<div class="variablelist"><dl class="variablelist">
<dt><span class="term"><code class="function">template gen_type&lt;Ranges&gt;::type</code></span></dt>
<dd><p>This type generator is used to specify the result of 
<code class="literal">Ranges</code> chained calls to
<code class="literal">extent_gen::operator[].</code> The types
<code class="computerout