<!-- fragment --><blockquote class="doxtable">
<p>#### Rationale for not providing a model for all contextually convertible to bool data types The <code>not_</code> method can not be implemented in a meaningful way for all of those types. For example, one can not cast a pointer type <code>T*</code> to bool and then back again to <code>T*</code> in a meaningful way. With an arithmetic type <code>T</code>, however, it is possible to cast from <code>T</code> to bool and then to <code>T</code> again; the result