Added value_initialized::swap documentation + test

[SVN r48425]

value_init.htm

@@ -253,7 +253,7 @@ its internal data, prior to constructing the object that it contains.
                    
 <h2><a name="val_init"><code>template class value_initialized&lt;T&gt;</code></a></h2>
                    
-<pre>namespace boost {<br><br>template&lt;class T&gt;<br>class value_initialized<br>{<br>  public :<br>    value_initialized() : x() {}<br>    operator T&amp;() const { return x ; }<br>    T&amp; data() const { return x ; }<br><br>  private :<br>    <i>unspecified</i> x ;<br>} ;<br><br>template&lt;class T&gt;<br>T const&amp; get ( value_initialized&lt;T&gt; const&amp; x )<br>{<br>  return x.data() ;<br>}<br><br>template&lt;class T&gt;<br>T&amp; get ( value_initialized&lt;T&gt;&amp; x )<br>{<br>  return x.data() ;<br>}<br><br>} // namespace boost<br></pre>
+<pre>namespace boost {<br><br>template&lt;class T&gt;<br>class value_initialized<br>{<br>  public :<br>    value_initialized() : x() {}<br>    operator T&amp;() const { return x ; }<br>    T&amp; data() const { return x ; }<br>    void swap( value_initialized&lt;T&gt;&amp; );<br><br>  private :<br>    <i>unspecified</i> x ;<br>} ;<br><br>template&lt;class T&gt;<br>T const&amp; get ( value_initialized&lt;T&gt; const&amp; x )<br>{<br>  return x.data() ;<br>}<br><br>template&lt;class T&gt;<br>T&amp; get ( value_initialized&lt;T&gt;&amp; x )<br>{<br>  return x.data() ;<br>}<br><br>} // namespace boost<br></pre>
                     
 <p>An object of this template class is a <code>T</code>-wrapper convertible 
     to <code>'T&amp;'</code> whose wrapped object (data member of type <code>T</code>) 
@@ -276,6 +276,10 @@ non-member    function <code>get()</code>:  </p>
 <p>Both <code>const</code> and non-<code>const</code> objects can be wrapped. 
     Mutable objects can be modified directly from within the wrapper but constant
     objects cannot:</p>
+
+<p>When <code>T</code> is a <em>Swappable</em> type, <code>value_initialized&lt;T&gt;</code>
+    is swappable as well, by calling its <code>swap</code> member function
+    as well as by calling <code>boost::swap</code>.</p>
                    
 <pre>value_initialized&lt;int&gt; x ; <br>static_cast&lt;int&amp;&gt;(x) = 1 ; // OK<br>get(x) = 1 ; // OK<br><br>value_initialized&lt;int const&gt; y ; <br>static_cast&lt;int&amp;&gt;(y) = 1 ; // ERROR: cannot cast to int&amp;<br>static_cast&lt;int const&amp;&gt;(y) = 1 ; // ERROR: cannot modify a const value<br>get(y) = 1 ; // ERROR: cannot modify a const value</pre>
                     
@@ -379,7 +383,7 @@ for Boost release version 1.35 (2008), offering a workaround to various compiler
      </p>
                     
 <hr>          
-<p>Revised 23 May 2008</p>
+<p>Revised 28 August 2008</p>
                    
 <p>&copy; Copyright Fernando Cacciola, 2002, 2008.</p>