StatisticVisualizerBase: Changed signalName parameter to be mandatory.

Author: levy

src/inet/visualizer/base/StatisticVisualizerBase.cc

@@ -62,6 +62,8 @@ void StatisticVisualizerBase::initialize(int stage)
         displayStatistics = par("displayStatistics");
         sourceFilter.setPattern(par("sourceFilter"));
         signalName = par("signalName");
+        if (opp_isempty(signalName))
+            throw cRuntimeError("The signalName parameter must be not empty");
         statisticName = par("statisticName");
         statisticUnit = par("statisticUnit");
         statisticExpression = par("statisticExpression");
@@ -92,18 +94,15 @@ void StatisticVisualizerBase::handleParameterChange(const char *name)
 
 void StatisticVisualizerBase::subscribe()
 {
-    if (*signalName != '\0')
-        visualizationSubjectModule->subscribe(registerSignal(signalName), this);
+    visualizationSubjectModule->subscribe(registerSignal(signalName), this);
 }
 
 void StatisticVisualizerBase::unsubscribe()
 {
     // NOTE: lookup the module again because it may have been deleted first
     auto visualizationSubjectModule = findModuleFromPar<cModule>(par("visualizationSubjectModule"), this);
-    if (visualizationSubjectModule != nullptr) {
-        if (*signalName != '\0')
-            visualizationSubjectModule->unsubscribe(registerSignal(signalName), this);
-    }
+    if (visualizationSubjectModule != nullptr)
+        visualizationSubjectModule->unsubscribe(registerSignal(signalName), this);
 }
 
 void StatisticVisualizerBase::addResultRecorder(cComponent *source, simsignal_t signal)