diff --git a/abstractsamplesource.cpp b/abstractsamplesource.cpp
new file mode 100644
index 0000000..04aa318
--- /dev/null
+++ b/abstractsamplesource.cpp
@@ -0,0 +1,42 @@
+/*
+ *  Copyright (C) 2017, Mike Walters <mike@flomp.net>
+ *
+ *  This file is part of inspectrum.
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "abstractsamplesource.h"
+
+void AbstractSampleSource::subscribe(Subscriber *subscriber)
+{
+	subscribers.insert(subscriber);
+}
+
+void AbstractSampleSource::invalidate()
+{
+	for (auto subscriber : subscribers) {
+		subscriber->invalidateEvent();
+	}
+}
+
+int AbstractSampleSource::subscriberCount()
+{
+	return subscribers.size();
+}
+
+void AbstractSampleSource::unsubscribe(Subscriber *subscriber)
+{
+	subscribers.erase(subscriber);
+}
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