="examples">Examples</h2>

<p>The above printable interface is an artificial example and you will not
find it in the STLplus library.</p>

<h3>The Persistent Interface</h3>

<p>This is an example taken from the STLplus library. I have defined a
<code>persistent</code> interface for use with polymorphic types. It is only used for
polymorphic types for which the best way of proving data persistence is
through virtual methods.</p>

<p>The <code>persistent</code> interface is defined by the following class:</p>