Make listener properties in StartLiveData dynamic

Framework/LiveData/inc/MantidLiveData/StartLiveData.h

@@ -57,6 +57,10 @@ class DLLExport StartLiveData : public LiveDataAlgorithm {
   void init() override;
   void exec() override;
   void afterPropertySet(const std::string &) override;
+
+  void copyListenerProperties(
+          const boost::shared_ptr<Mantid::API::ILiveListener> &listener);
+  void removeListenerProperties();
 };
 
 } // namespace LiveData

Framework/LiveData/src/StartLiveData.cpp

@@ -76,28 +76,43 @@ void StartLiveData::init() {
  */
 void StartLiveData::afterPropertySet(const std::string &propName) {
   if (propName == "Instrument") {
-    // Remove old listener's properties
-    const std::vector<Property *> existingProps = getProperties();
-    for (auto existingProp : existingProps) {
-      if (existingProp->getGroup() == listenerPropertyGroup) {
-        removeProperty(existingProp->name());
-      }
-    }
+    // Properties of old listener, if any, need to be removed
+    removeListenerProperties();
 
-    // Add new listener's properties
+    // Get of instance of listener for this instrument
     auto listener = LiveListenerFactory::Instance().create(
         getPropertyValue(propName), false);
-    auto propertyManagerListener =
-        boost::dynamic_pointer_cast<IPropertyManager>(listener);
-
-    if (propertyManagerListener) {
-      const std::vector<Property *> listenerProps =
-          propertyManagerListener->getProperties();
-      for (auto listenerProp : listenerProps) {
-        auto prop = std::unique_ptr<Property>(listenerProp->clone());
-        prop->setGroup(listenerPropertyGroup);
-        declareProperty(std::move(prop));
-      }
+
+    // Copy over properties of new listener to this algorithm
+    copyListenerProperties(listener);
+  }
+}
+
+/**
+ * Copies properties from an ILiveListener to this algorithm. This makes them
+ * appear in the "listener properties" group on the StartLiveData custom dialog.
+ *
+ * @param listener ILiveListener from which to copy properties
+ */
+void StartLiveData::copyListenerProperties(const boost::shared_ptr<ILiveListener> &listener)
+{
+  // Add clones of listener's properties to this algorithm
+  for (auto listenerProp : listener->getProperties()) {
+    auto prop = std::unique_ptr<Property>(listenerProp->clone());
+    prop->setGroup(listenerPropertyGroup);
+    declareProperty(std::move(prop));
+  }
+}
+
+/**
+ * Removes previously copied ILiveListener properties.
+ */
+void StartLiveData::removeListenerProperties()
+{
+  // Remove all properties tagged with the listener property group
+  for (auto prop : getProperties()) {
+    if (prop->getGroup() == listenerPropertyGroup) {
+      removeProperty(prop->name());
     }
   }
 }

docs/source/algorithms/StartLiveData-v1.rst

@@ -23,6 +23,29 @@ simply calls :ref:`algm-LoadLiveData` at a fixed interval.
 Instructions for setting up a "fake" data stream are found `here
 <http://www.mantidproject.org/MBC_Live_Data_Simple_Examples>`__.
 
+Listener Properties
+###################
+
+Specific LiveListeners may provide their own properties, in addition to
+properties provided by StartLiveData. For convenience and accessibility, these
+properties are made available through StartLiveData as well.
+
+In the StartLiveData algorithm dialog, a group box called "Listener Properties"
+will appear at the bottom of the sidebar on the left, if the currently selected
+listener provides additional properties.
+
+In the Python API, these listener properties may also be set as keyword
+arguments when calling StartLiveData. For example, in this code snippet:
+
+.. code-block:: python
+
+    StartLiveData(Instrument='ISIS_Histogram', OutputWorkspace='wsOut', UpdateEvery=1,
+                  AccumulationMethod='Replace', PeriodList=[1,3], SpectraList=[2,4,6])
+
+PeriodList and SpectraList are properties of the ISISHistoDataListener. They
+are available as arguments in this call because Instrument is set to
+'ISIS_Histogram', which uses that listener.
+
 Live Plots
 ##########
 

docs/source/release/v3.9.0/framework.rst

@@ -41,7 +41,7 @@ Python Algorithms
 
 - :ref:`MatchPeaks <algm-MatchPeaks>` performs circular shift operation (numpy roll) along the x-axis to align the peaks in the spectra.
 - :ref:`FindEPP <algm-FindEPP>` is improved to better determine the initial parameters and range for the fitting.
-- :ref:`StartLiveData <algm-StartLiveData>` can now accept LiveListener properties as parameters, based on the Instrument parameter.
+- :ref:`StartLiveData <algm-StartLiveData>` can now accept LiveListener properties as parameters, based on the value of the "Instrument" parameter.
 
 Bug Fixes
 ---------