Navradio: constructor cleanup, tie/untie helper, and a new 'operable' property to make it clear when the radio is functioning.

src/Instrumentation/navradio.cxx

@@ -94,56 +94,6 @@ FGNavRadio::FGNavRadio(SGPropertyNode *node) :
     lon_node(fgGetNode("/position/longitude-deg", true)),
     lat_node(fgGetNode("/position/latitude-deg", true)),
     alt_node(fgGetNode("/position/altitude-ft", true)),
-    is_valid_node(NULL),
-    power_btn_node(NULL),
-    freq_node(NULL),
-    alt_freq_node(NULL),
-    sel_radial_node(NULL),
-    vol_btn_node(NULL),
-    ident_btn_node(NULL),
-    audio_btn_node(NULL),
-    backcourse_node(NULL),
-    nav_serviceable_node(NULL),
-    cdi_serviceable_node(NULL),
-    gs_serviceable_node(NULL),
-    tofrom_serviceable_node(NULL),
-    dme_serviceable_node(NULL),
-    fmt_freq_node(NULL),
-    fmt_alt_freq_node(NULL),
-    heading_node(NULL),
-    radial_node(NULL),
-    recip_radial_node(NULL),
-    target_radial_true_node(NULL),
-    target_auto_hdg_node(NULL),
-    time_to_intercept(NULL),
-    to_flag_node(NULL),
-    from_flag_node(NULL),
-    inrange_node(NULL),
-    signal_quality_norm_node(NULL),
-    cdi_deflection_node(NULL),
-    cdi_deflection_norm_node(NULL),
-    cdi_xtrack_error_node(NULL),
-    cdi_xtrack_hdg_err_node(NULL),
-    has_gs_node(NULL),
-    loc_node(NULL),
-    loc_dist_node(NULL),
-    gs_deflection_node(NULL),
-    gs_deflection_deg_node(NULL),
-    gs_deflection_norm_node(NULL),
-    gs_rate_of_climb_node(NULL),
-    gs_dist_node(NULL),
-    gs_inrange_node(NULL),
-    nav_id_node(NULL),
-    id_c1_node(NULL),
-    id_c2_node(NULL),
-    id_c3_node(NULL),
-    id_c4_node(NULL),
-    nav_slaved_to_gps_node(NULL),
-    gps_cdi_deflection_node(NULL),
-    gps_to_flag_node(NULL),
-    gps_from_flag_node(NULL),
-    gps_has_gs_node(NULL),
-    gps_xtrack_error_nm_node(NULL),
     play_count(0),
     last_time(0),
     target_radial(0.0),
@@ -169,6 +119,10 @@ FGNavRadio::FGNavRadio(SGPropertyNode *node) :
     term_tbl = new SGInterpTable( term.str() );
     low_tbl = new SGInterpTable( low.str() );
     high_tbl = new SGInterpTable( high.str() );
+    
+    
+    string branch("/instrumentation/" + _name);
+    _radio_node = fgGetNode(branch.c_str(), _num, true);
 }
 
 
@@ -190,11 +144,7 @@ FGNavRadio::init ()
 
     morse.init();
 
-    string branch;
-    branch = "/instrumentation/" + _name;
-
-    SGPropertyNode *node = fgGetNode(branch.c_str(), _num, true );
-
+    SGPropertyNode* node = _radio_node.get();
     bus_power_node = 
 	fgGetNode(("/systems/electrical/outputs/" + _name).c_str(), true);
 
@@ -267,8 +217,6 @@ FGNavRadio::init ()
     id_c3_node = node->getChild("nav-id_asc3", 0, true);
     id_c4_node = node->getChild("nav-id_asc4", 0, true);
 
-    node->tie("dme-in-range", SGRawValuePointer<bool>(&_dmeInRange));
-        
     // gps slaving support
     nav_slaved_to_gps_node = node->getChild("slaved-to-gps", 0, true);
     gps_cdi_deflection_node = fgGetNode("/instrumentation/gps/cdi-deflection", true);
@@ -289,13 +237,18 @@ FGNavRadio::init ()
 void
 FGNavRadio::bind ()
 {
-  
+  tie("dme-in-range", SGRawValuePointer<bool>(&_dmeInRange));
+  tie("operable", SGRawValueMethods<FGNavRadio, bool>(*this, &FGNavRadio::isOperable, NULL));
 }
 
 
 void
 FGNavRadio::unbind ()
 {
+  for (unsigned int t=0; t<_tiedNodes.size(); ++t) {
+    _tiedNodes[t]->untie();
+  }
+  _tiedNodes.clear();
 }
 
 
@@ -387,7 +340,8 @@ FGNavRadio::update(double dt)
   if (power_btn_node->getBoolValue() 
       && (bus_power_node->getDoubleValue() > 1.0)
       && nav_serviceable_node->getBoolValue() )
-  {   
+  {
+    _operable = true;
     if (nav_slaved_to_gps_node->getBoolValue()) {
       updateGPSSlaved();
     } else {
@@ -419,6 +373,7 @@ void FGNavRadio::clearOutputs()
   from_flag_node->setBoolValue( false );
   
   _dmeInRange = false;
+  _operable = false;
 }
 
 void FGNavRadio::updateReceiver(double dt)

src/Instrumentation/navradio.hxx

@@ -47,6 +47,7 @@ class FGNavRadio : public SGSubsystem
     SGInterpTable *low_tbl;
     SGInterpTable *high_tbl;
 
+    SGPropertyNode_ptr _radio_node;
     SGPropertyNode_ptr lon_node;
     SGPropertyNode_ptr lat_node;
     SGPropertyNode_ptr alt_node;
@@ -125,6 +126,7 @@ class FGNavRadio : public SGSubsystem
 
     // internal (private) values
 
+    bool _operable; ///< is the unit serviceable, on, powered, etc
     int play_count;
     time_t last_time;
     FGNavRecordPtr _navaid;
@@ -165,6 +167,7 @@ class FGNavRadio : public SGSubsystem
     double _gsNeedleDeflectionNorm;
     
     SGSharedPtr<SGSampleGroup> _sgr;
+    std::vector<SGPropertyNode*> _tiedNodes;
     
     bool updateWithPower(double aDt);
 
@@ -193,6 +196,21 @@ class FGNavRadio : public SGSubsystem
      */
     double localizerWidth(FGNavRecord* aLOC);
     FGNavRecord* findPrimaryNavaid(const SGGeod& aPos, double aFreqMHz);
+    
+    /// accessor for tied, read-only 'operable' property
+    bool isOperable() const
+      { return _operable; }
+      
+    /**
+     * Tied-properties helper, record nodes which are tied for easy un-tie-ing
+     */
+    template <typename T>
+    void tie(const char* aRelPath, const SGRawValue<T>& aRawValue)
+    {
+      SGPropertyNode* nd = _radio_node->getNode(aRelPath, true);
+      _tiedNodes.push_back(nd);
+      nd->tie(aRawValue);
+    }
 public:
 
     FGNavRadio(SGPropertyNode *node);