'PerlIO::via::dynamic' is used for creating dynamic the PerlIO manpage
layers. It is useful when the behavior or the layer depends on variables.
You should not use this module as via layer directly (ie :via(dynamic)).

Use the constructor to create new layers, with two arguments: translate and
untranslate. Then use '$p-'via ($fh)> to wrap the handle. Once <$fh> is
destroyed, the temporary namespace for the IO layer will be removed.

Note that PerlIO::via::dynamic uses the scalar fields to reference to the
object representing the dynamic namespace.