e client is to post custom alerts.</p>
<p>The expected interface of any <a class="reference external" href="reference-Alerts.html#alert">alert</a>, apart from deriving from the <a class="reference external" href="reference-Alerts.html#alert">alert</a>
base class, looks like this:</p>
<pre class="literal-block">
static const int alert_type = <em>&lt;unique alert ID&gt;</em>;
virtual int type() const { return alert_type; }

virtual std::string message() const;

static const alert_category_t static_category = 