nclosed member. The template class
      has several (explicit) constructor member templates, which implicitly type
      the constructor arguments and pass them to the member. The template class uses
      implicit copy construction and assignment, cancelling them if the enclosed
      member is non-copyable.
    </p>
<p>
      Manually coding a base class may be better if the construction and/or copying
      needs are too complex for the supplied template class, or if the compiler is
      not advanced e