4 files changed, 158 insertions, 0 deletions
diff --git a/host/include/uhd/CMakeLists.txt b/host/include/uhd/CMakeLists.txt
index 74dc4a7d6..c3c51279c 100644
--- a/host/include/uhd/CMakeLists.txt
+++ b/host/include/uhd/CMakeLists.txt
@@ -26,6 +26,7 @@ INSTALL(FILES
     convert.hpp
     device.hpp
     exception.hpp
+    property.hpp
     version.hpp
     wax.hpp
     DESTINATION ${INCLUDE_DIR}/uhd
diff --git a/host/include/uhd/property.hpp b/host/include/uhd/property.hpp
new file mode 100644
index 000000000..5b47f9482
--- /dev/null
+++ b/host/include/uhd/property.hpp
@@ -0,0 +1,81 @@
+//
+// Copyright 2011 Ettus Research LLC
+//
+// 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/>.
+//
+
+#ifndef INCLUDED_UHD_PROPERTY_HPP
+#define INCLUDED_UHD_PROPERTY_HPP
+
+#include <uhd/config.hpp>
+#include <boost/foreach.hpp>
+#include <boost/function.hpp>
+#include <list>
+
+namespace uhd{
+
+template <typename T> class property{
+public:
+    typedef boost::function<void(const T &)> subscriber_type;
+    typedef boost::function<T(const T &)> master_type;
+
+    /*!
+     * Register a master subscriber into the property.
+     * A master is a special subscriber that coerces the value.
+     * Only one master may be registered per property.
+     * Registering a master replaces the previous master.
+     */
+    void subscribe_master(const master_type &master){
+        _master = master;
+    }
+
+    /*!
+     * Register a subscriber into the property.
+     * All subscribers are called when the value changes.
+     * Once a subscriber is registered, it cannot be unregistered.
+     */
+    void subscribe(const subscriber_type &subscriber){
+        _subscribers.push_back(subscriber);
+    }
+
+    //! Update calls all subscribers w/ the current value
+    void update(void){
+        this->set(this->get());
+    }
+
+    /*!
+     * Set the new value and call all subscribers.
+     * The master is called first to coerce the value.
+     */
+    void set(const T &value){
+        _value = _master.empty()? value : _master(value);
+        BOOST_FOREACH(subscriber_type &subscriber, _subscribers){
+            subscriber(_value); //let errors propagate
+        }
+    }
+
+    //! Get the current value of this property
+    T get(void) const{
+        return _value;
+    }
+
+private:
+    std::list<subscriber_type> _subscribers;
+    master_type _master;
+    T _value;
+};
+
+} //namespace uhd
+
+#endif /* INCLUDED_UHD_PROPERTY_HPP */
diff --git a/host/tests/CMakeLists.txt b/host/tests/CMakeLists.txt
index b7bcfb7d5..133763591 100644
--- a/host/tests/CMakeLists.txt
+++ b/host/tests/CMakeLists.txt
@@ -27,6 +27,7 @@ SET(test_sources
     error_test.cpp
     gain_group_test.cpp
     msg_test.cpp
+    property_test.cpp
     ranges_test.cpp
     sph_recv_test.cpp
     sph_send_test.cpp
diff --git a/host/tests/property_test.cpp b/host/tests/property_test.cpp
new file mode 100644
index 000000000..c5ef7f1c9
--- /dev/null
+++ b/host/tests/property_test.cpp
@@ -0,0 +1,75 @@
+//
+// Copyright 2011 Ettus Research LLC
+//
+// 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 <boost/test/unit_test.hpp>
+#include <uhd/property.hpp>
+#include <boost/bind.hpp>
+
+struct coercer_type{
+    int doit(int x){
+        return x & ~0x3;
+    }
+};
+
+struct setter_type{
+    void doit(int x){
+        _x = x;
+    }
+
+    int _x;
+};
+
+BOOST_AUTO_TEST_CASE(test_prop_simple){
+    uhd::property<int> prop;
+    prop.set(42);
+    BOOST_CHECK_EQUAL(prop.get(), 42);
+    prop.set(34);
+    BOOST_CHECK_EQUAL(prop.get(), 34);
+}
+
+BOOST_AUTO_TEST_CASE(test_prop_with_subscriber){
+    uhd::property<int> prop;
+
+    setter_type setter;
+    prop.subscribe(boost::bind(&setter_type::doit, &setter, _1));
+
+    prop.set(42);
+    BOOST_CHECK_EQUAL(prop.get(), 42);
+    BOOST_CHECK_EQUAL(setter._x, 42);
+
+    prop.set(34);
+    BOOST_CHECK_EQUAL(prop.get(), 34);
+    BOOST_CHECK_EQUAL(setter._x, 34);
+}
+
+BOOST_AUTO_TEST_CASE(test_prop_with_coercion){
+    uhd::property<int> prop;
+
+    setter_type setter;
+    prop.subscribe(boost::bind(&setter_type::doit, &setter, _1));
+
+    coercer_type coercer;
+    prop.subscribe_master(boost::bind(&coercer_type::doit, &coercer, _1));
+
+    prop.set(42);
+    BOOST_CHECK_EQUAL(prop.get(), 40);
+    BOOST_CHECK_EQUAL(setter._x, 40);
+
+    prop.set(34);
+    BOOST_CHECK_EQUAL(prop.get(), 32);
+    BOOST_CHECK_EQUAL(setter._x, 32);
+}