the data will be read.
              </p></dd>
<dt><span class="term">completion_condition</span></dt>
<dd>
<p>
                The function object to be called to determine whether the read operation
                is complete. The signature of the function object must be:
</p>
<pre class="programlisting">std::size_t completion_condition(
  // Result of latest read_some_at operation.
  const boost::system::error_code&amp; error,

  // Number of bytes transferred so far.
  std::size_t bytes_transferred
);
