Redefine the factories for track views and controls...

... non-intrusively in the Track suclasses, registering functions instead.

For each abstract factory function (of two), build a table of concrete factory
functions, paralleling the hierarchy of Track subclesses.  Dispatch using
runt time type information in the Track objects.

src/LabelTrack.h

@@ -169,10 +169,6 @@ public:
    double mClipLen;
 
    int miLastLabel;                 // used by FindNextLabel and FindPrevLabel
-
-private:
-   std::shared_ptr<TrackView> DoGetView() override;
-   std::shared_ptr<TrackControls> DoGetControls() override;
 };
 
 struct LabelTrackEvent : TrackListEvent

src/NoteTrack.h

@@ -222,10 +222,6 @@ public:
    int mVisibleChannels; // bit set of visible channels
 
    std::weak_ptr<StretchHandle> mStretchHandle;
-
-protected:
-   std::shared_ptr<TrackView> DoGetView() override;
-   std::shared_ptr<TrackControls> DoGetControls() override;
 };
 
 /// Data used to display a note track

src/TimeTrack.h

@@ -113,10 +113,6 @@ private:
    Track::Holder Clone() const override;
 
    friend class TrackFactory;
-
-protected:
-   std::shared_ptr<TrackView> DoGetView() override;
-   std::shared_ptr<TrackControls> DoGetControls() override;
 };
 
 

src/Track.cpp

@@ -1284,3 +1284,13 @@ void TrackFactory::Destroy( AudacityProject &project )
 {
    project.AttachedObjects::Assign( key2, nullptr );
 }
+
+template<> auto DoGetControls::Implementation() -> Function {
+   return nullptr;
+}
+static DoGetControls registerDoGetControls;
+
+template<> auto DoGetView::Implementation() -> Function {
+   return nullptr;
+}
+static DoGetView registerDoGetView;

src/Track.h

@@ -704,12 +704,6 @@ public:
    bool HandleCommonXMLAttribute(const wxChar *attr, const wxChar *value);
 
 protected:
-
-   // These are called to create controls on demand:
-   virtual std::shared_ptr<TrackView> DoGetView() = 0;
-   virtual std::shared_ptr<TrackControls> DoGetControls() = 0;
-
-   // These hold the controls:
    std::shared_ptr<TrackView> mpView;
    std::shared_ptr<CommonTrackCell> mpControls;
 };
@@ -1595,4 +1589,24 @@ class AUDACITY_DLL_API TrackFactory final
 #endif
 };
 
+#include "AttachedVirtualFunction.h"
+
+struct DoGetControlsTag;
+
+using DoGetControls =
+AttachedVirtualFunction<
+   DoGetControlsTag,
+   std::shared_ptr< TrackControls >,
+   Track
+>;
+
+struct DoGetViewTag;
+
+using DoGetView =
+AttachedVirtualFunction<
+   DoGetViewTag,
+   std::shared_ptr< TrackView >,
+   Track
+>;
+
 #endif

src/WaveTrack.h

@@ -682,10 +682,6 @@ private:
 
    std::unique_ptr<SpectrogramSettings> mpSpectrumSettings;
    std::unique_ptr<WaveformSettings> mpWaveformSettings;
-
-protected:
-   std::shared_ptr<TrackView> DoGetView() override;
-   std::shared_ptr<TrackControls> DoGetControls() override;
 };
 
 // This is meant to be a short-lived object, during whose lifetime,

src/tracks/labeltrack/ui/LabelTrackControls.cpp

@@ -170,3 +170,11 @@ PopupMenuTable *LabelTrackControls::GetMenuExtension(Track *)
 {
    return &LabelTrackMenuTable::Instance();
 }
+
+using DoGetLabelTrackControls = DoGetControls::Override< LabelTrack >;
+template<> template<> auto DoGetLabelTrackControls::Implementation() -> Function {
+   return [](LabelTrack &track) {
+      return std::make_shared<LabelTrackControls>( track.SharedPointer() );
+   };
+}
+static DoGetLabelTrackControls registerDoGetLabelTrackControls;

src/tracks/labeltrack/ui/LabelTrackView.cpp

@@ -2080,15 +2080,13 @@ int LabelTrackView::DialogForLabelName(
    return status;
 }
 
-std::shared_ptr<TrackView> LabelTrack::DoGetView()
-{
-   return std::make_shared<LabelTrackView>( SharedPointer() );
-}
-
-std::shared_ptr<TrackControls> LabelTrack::DoGetControls()
-{
-   return std::make_shared<LabelTrackControls>( SharedPointer() );
+using DoGetLabelTrackView = DoGetView::Override< LabelTrack >;
+template<> template<> auto DoGetLabelTrackView::Implementation() -> Function {
+   return [](LabelTrack &track) {
+      return std::make_shared<LabelTrackView>( track.SharedPointer() );
+   };
 }
+static DoGetLabelTrackView registerDoGetLabelTrackView;
 
 std::shared_ptr<TrackVRulerControls> LabelTrackView::DoGetVRulerControls()
 {

src/tracks/playabletrack/notetrack/ui/NoteTrackControls.cpp

@@ -310,3 +310,11 @@ void NoteTrackControls::ReCreateVelocitySlider( wxEvent &evt )
    pParent;
 #endif
 }
+
+using DoGetNoteTrackControls = DoGetControls::Override< NoteTrack >;
+template<> template<> auto DoGetNoteTrackControls::Implementation() -> Function {
+   return [](NoteTrack &track) {
+      return std::make_shared<NoteTrackControls>( track.SharedPointer() );
+   };
+}
+static DoGetNoteTrackControls registerDoGetNoteTrackControls;

src/tracks/playabletrack/notetrack/ui/NoteTrackView.cpp

@@ -53,15 +53,13 @@ std::vector<UIHandlePtr> NoteTrackView::DetailedHitTest
    return results;
 }
 
-std::shared_ptr<TrackView> NoteTrack::DoGetView()
-{
-   return std::make_shared<NoteTrackView>( SharedPointer() );
-}
-
-std::shared_ptr<TrackControls> NoteTrack::DoGetControls()
-{
-   return std::make_shared<NoteTrackControls>( SharedPointer() );
+using DoGetNoteTrackView = DoGetView::Override< NoteTrack >;
+template<> template<> auto DoGetNoteTrackView::Implementation() -> Function {
+   return [](NoteTrack &track) {
+      return std::make_shared<NoteTrackView>( track.SharedPointer() );
+   };
 }
+static DoGetNoteTrackView registerDoGetNoteTrackView;
 
 std::shared_ptr<TrackVRulerControls> NoteTrackView::DoGetVRulerControls()
 {

src/tracks/playabletrack/wavetrack/ui/WaveTrackControls.cpp

@@ -1283,3 +1283,11 @@ void WaveTrackControls::ReCreatePanSlider( wxEvent &event )
                                PAN_SLIDER);
    gPanCaptured->SetDefaultValue(defPos);
 }
+
+using DoGetWaveTrackControls = DoGetControls::Override< WaveTrack >;
+template<> template<> auto DoGetWaveTrackControls::Implementation() -> Function {
+   return [](WaveTrack &track) {
+      return std::make_shared<WaveTrackControls>( track.SharedPointer() );
+   };
+}
+static DoGetWaveTrackControls registerDoGetWaveTrackControls;

src/tracks/playabletrack/wavetrack/ui/WaveTrackView.cpp

@@ -156,15 +156,13 @@ void WaveTrackView::DoSetMinimized( bool minimized )
    TrackView::DoSetMinimized( minimized );
 }
 
-std::shared_ptr<TrackView> WaveTrack::DoGetView()
-{
-   return std::make_shared<WaveTrackView>( SharedPointer() );
-}
-
-std::shared_ptr<TrackControls> WaveTrack::DoGetControls()
-{
-   return std::make_shared<WaveTrackControls>( SharedPointer() );
+using DoGetWaveTrackView = DoGetView::Override< WaveTrack >;
+template<> template<> auto DoGetWaveTrackView::Implementation() -> Function {
+   return [](WaveTrack &track) {
+      return std::make_shared<WaveTrackView>( track.SharedPointer() );
+   };
 }
+static DoGetWaveTrackView registerDoGetWaveTrackView;
 
 std::shared_ptr<TrackVRulerControls> WaveTrackView::DoGetVRulerControls()
 {

src/tracks/timetrack/ui/TimeTrackControls.cpp

@@ -170,3 +170,11 @@ PopupMenuTable *TimeTrackControls::GetMenuExtension(Track *)
 {
    return &TimeTrackMenuTable::Instance();
 }
+
+using DoGetTimeTrackControls = DoGetControls::Override< TimeTrack >;
+template<> template<> auto DoGetTimeTrackControls::Implementation() -> Function {
+   return [](TimeTrack &track) {
+      return std::make_shared<TimeTrackControls>( track.SharedPointer() );
+   };
+}
+static DoGetTimeTrackControls registerDoGetTimeTrackControls;

src/tracks/timetrack/ui/TimeTrackView.cpp

@@ -43,15 +43,13 @@ std::vector<UIHandlePtr> TimeTrackView::DetailedHitTest
    return results;
 }
 
-std::shared_ptr<TrackView> TimeTrack::DoGetView()
-{
-   return std::make_shared<TimeTrackView>( SharedPointer() );
-}
-
-std::shared_ptr<TrackControls> TimeTrack::DoGetControls()
-{
-   return std::make_shared<TimeTrackControls>( SharedPointer() );
+using DoGetTimeTrackView = DoGetView::Override< TimeTrack >;
+template<> template<> auto DoGetTimeTrackView::Implementation() -> Function {
+   return [](TimeTrack &track) {
+      return std::make_shared<TimeTrackView>( track.SharedPointer() );
+   };
 }
+static DoGetTimeTrackView registerDoGetTimeTrackView;
 
 std::shared_ptr<TrackVRulerControls> TimeTrackView::DoGetVRulerControls()
 {

src/tracks/ui/TrackView.cpp

@@ -57,7 +57,7 @@ std::shared_ptr<TrackView> Track::GetTrackView()
 {
    if (!mpView)
       // create on demand
-      mpView = DoGetView();
+      mpView = DoGetView::Call( *this );
    return mpView;
 }
 
@@ -70,7 +70,7 @@ std::shared_ptr<TrackPanelCell> Track::GetTrackControls()
 {
    if (!mpControls)
       // create on demand
-      mpControls = DoGetControls();
+      mpControls = DoGetControls::Call( *this );
    return mpControls;
 }