n valid while operations are carried out on the descriptor.  If
&rsquo;file&rsquo; is a buffered port, buffering will be taken into account in
indicating whether a read can be made without blocking (but on a
buffered port, for efficiency purposes each read operation in response
to this watch should usually exhaust the buffer by calling drain-input
or by looping on char-ready?).
</p>
<p>This procedure should not throw an exception unless memory is
exhausted.
</p></dd></dl>

<dl class="def">
<dt id="index-eve