Calls to Disconnect or Unbind in destructors are not needed, if...

... it's either the source of the connection that is being destroyed, or other
object (such as an ancestor window) transitively owning it and so causing it to
be destroyed too;

or, the sink is being destroyed, and that sink is a wxEvtHandler (which is
always so for Disconnect, though not for Unbind in case Bind was passed a
member function of a non-wxEvtHandler).

wxWidgets takes care of erasing the connection in such cases.

This removes most calls to Disconnect and Unbind.  Many destructors shrank to
nothing.

Notably, in case of popup menu handling, the call to Disconnect is not removable
because the object being destroyed is neither the source nor the sink.

src/AudacityLogger.cpp

@@ -57,11 +57,6 @@ AudacityLogger::AudacityLogger()
    mUpdated = false;
 }
 
-AudacityLogger::~AudacityLogger()
-{
-   Destroy();
-}
-
 void AudacityLogger::Flush()
 {
    if (mUpdated && mFrame && mFrame->IsShown()) {
@@ -95,50 +90,6 @@ void AudacityLogger::DoLogText(const wxString & str)
    }
 }
 
-void AudacityLogger::Destroy()
-{
-   if (mFrame) {
-      mFrame->Disconnect(LoggerID_Save,
-                        wxEVT_COMMAND_BUTTON_CLICKED,
-                        wxCommandEventHandler(AudacityLogger::OnSave),
-                        NULL,
-                        this);
-      mFrame->Disconnect(LoggerID_Clear,
-                        wxEVT_COMMAND_BUTTON_CLICKED,
-                        wxCommandEventHandler(AudacityLogger::OnClear),
-                        NULL,
-                        this);
-      mFrame->Disconnect(LoggerID_Close,
-                        wxEVT_COMMAND_BUTTON_CLICKED,
-                        wxCommandEventHandler(AudacityLogger::OnClose),
-                        NULL,
-                        this);
-
-      mFrame->Disconnect(LoggerID_Save,
-                        wxEVT_COMMAND_MENU_SELECTED,
-                        wxCommandEventHandler(AudacityLogger::OnSave),
-                        NULL,
-                        this);
-      mFrame->Disconnect(LoggerID_Clear,
-                        wxEVT_COMMAND_MENU_SELECTED,
-                        wxCommandEventHandler(AudacityLogger::OnClear),
-                        NULL,
-                        this);
-      mFrame->Disconnect(LoggerID_Close,
-                        wxEVT_COMMAND_MENU_SELECTED,
-                        wxCommandEventHandler(AudacityLogger::OnClose),
-                        NULL,
-                        this);
-
-      mFrame->Disconnect(wxEVT_CLOSE_WINDOW,
-                        wxCloseEventHandler(AudacityLogger::OnCloseWindow),
-                        NULL,
-                        this);
-
-      mFrame.reset();
-   }
-}
-
 void AudacityLogger::Show(bool show)
 {
    // Hide the frame if created, otherwise do nothing
@@ -272,7 +223,7 @@ void AudacityLogger::OnCloseWindow(wxCloseEvent & WXUNUSED(e))
    // On the Mac, destroy the window rather than hiding it since the
    // log menu will override the root windows menu if there is no
    // project window open.
-   Destroy();
+   mFrame.reset();
 #else
    Show(false);
 #endif

src/AudacityLogger.h

@@ -28,10 +28,8 @@
 class AudacityLogger final : public wxEvtHandler, public wxLog {
  public:
    AudacityLogger();
-   virtual ~AudacityLogger();
 
    void Show(bool show = true);
-   void Destroy();
 
 #if defined(EXPERIMENTAL_CRASH_REPORT)
    wxString GetLog();

src/HistoryWindow.cpp

@@ -152,21 +152,6 @@ HistoryWindow::HistoryWindow(AudacityProject *parent, UndoManager *manager):
                      this);
 }
 
-HistoryWindow::~HistoryWindow()
-{
-   wxTheApp->Disconnect(EVT_AUDIOIO_PLAYBACK,
-                        wxCommandEventHandler(HistoryWindow::OnAudioIO),
-                        NULL,
-                        this);
-
-   wxTheApp->Disconnect(EVT_AUDIOIO_CAPTURE,
-                        wxCommandEventHandler(HistoryWindow::OnAudioIO),
-                        NULL,
-                        this);
-
-   mAvail->Disconnect(wxEVT_KEY_DOWN, wxKeyEventHandler(HistoryWindow::OnChar));
-}
-
 void HistoryWindow::OnAudioIO(wxCommandEvent& evt)
 {
    evt.Skip();

src/HistoryWindow.h

@@ -28,7 +28,6 @@ class HistoryWindow final : public wxDialogWrapper {
 
  public:
    HistoryWindow(AudacityProject * parent, UndoManager *manager);
-   ~HistoryWindow();
 
    void UpdateDisplay();
 

src/LyricsWindow.cpp

@@ -133,14 +133,6 @@ LyricsWindow::LyricsWindow(AudacityProject *parent):
    Center();
 }
 
-LyricsWindow::~LyricsWindow()
-{
-   mProject->Disconnect(EVT_TRACK_PANEL_TIMER,
-      wxCommandEventHandler(LyricsWindow::OnTimer),
-      NULL,
-      this);
-}
-
 void LyricsWindow::OnCloseWindow(wxCloseEvent & WXUNUSED(event))
 {
   this->Hide();

src/LyricsWindow.h

@@ -23,7 +23,6 @@ class LyricsWindow final : public wxFrame {
 
  public:
    LyricsWindow(AudacityProject* parent);
-   virtual ~LyricsWindow();
 
    LyricsPanel *GetLyricsPanel() { return mLyricsPanel; };
 

src/MixerBoard.cpp

@@ -934,17 +934,6 @@ MixerBoard::MixerBoard(AudacityProject* pProject,
       this);
 }
 
-MixerBoard::~MixerBoard()
-{
-   // private data members
-   mMusicalInstruments.clear();
-
-   mProject->Disconnect(EVT_TRACK_PANEL_TIMER,
-      wxCommandEventHandler(MixerBoard::OnTimer),
-      NULL,
-      this);
-}
-
 
 
 

src/MixerBoard.h

@@ -206,7 +206,6 @@ public:
                wxFrame* parent,
                const wxPoint& pos = wxDefaultPosition,
                const wxSize& size = wxDefaultSize);
-   virtual ~MixerBoard();
 
    void UpdatePrefs();
 

src/PluginManager.cpp

@@ -423,7 +423,6 @@ class PluginRegistrationDialog final : public wxDialogWrapper
 public:
    // constructors and destructors
    PluginRegistrationDialog(wxWindow *parent, EffectType type);
-   virtual ~PluginRegistrationDialog();
 
 private:
    void Populate();
@@ -501,14 +500,6 @@ PluginRegistrationDialog::PluginRegistrationDialog(wxWindow *parent, EffectType
    Populate();
 }
 
-PluginRegistrationDialog::~PluginRegistrationDialog()
-{
-   mEffects->Disconnect(wxEVT_KEY_DOWN,
-                        wxKeyEventHandler(PluginRegistrationDialog::OnListChar),
-                        NULL,
-                        this);
-}
-
 void PluginRegistrationDialog::Populate()
 {
    //------------------------- Main section --------------------

src/Project.cpp

@@ -1258,11 +1258,6 @@ AudacityProject::~AudacityProject()
       mTrackPanel->RemoveOverlay(mCursorOverlay.get());
       mTrackPanel->RemoveOverlay(mIndicatorOverlay.get());
    }
-
-   wxTheApp->Disconnect(EVT_AUDIOIO_CAPTURE,
-                     wxCommandEventHandler(AudacityProject::OnCapture),
-                     NULL,
-                     this);
 }
 
 void AudacityProject::ApplyUpdatedTheme()
@@ -2715,11 +2710,6 @@ void AudacityProject::OnCloseWindow(wxCloseEvent & event)
 #endif
    }
 
-   this->Disconnect(EVT_TRACK_PANEL_TIMER,
-      wxCommandEventHandler(ViewInfo::OnTimer),
-      NULL,
-      &mViewInfo);
-
    // Destroys this
    pSelf.reset();
    mRuler = nullptr;
@@ -6038,14 +6028,6 @@ AudacityProject::PlaybackScroller::PlaybackScroller(AudacityProject *project)
                      this);
 }
 
-AudacityProject::PlaybackScroller::~PlaybackScroller()
-{
-   mProject->Disconnect(EVT_TRACK_PANEL_TIMER,
-                        wxCommandEventHandler(PlaybackScroller::OnTimer),
-                        NULL,
-                        this);
-}
-
 void AudacityProject::PlaybackScroller::OnTimer(wxCommandEvent &event)
 {
    // Let other listeners get the notification

src/Project.h

@@ -793,7 +793,6 @@ public:
    {
    public:
       explicit PlaybackScroller(AudacityProject *project);
-      ~PlaybackScroller();
 
       enum class Mode {
          Off,

src/Track.cpp

@@ -770,7 +770,7 @@ Track *SyncLockedTracksIterator::Last(bool skiplinked)
 //
 // The TrackList sends events whenever certain updates occur to the list it
 // is managing.  Any other classes that may be interested in get these updates
-// should use TrackList::Connect() and TrackList::Disconnect().
+// should use TrackList::Connect() or TrackList::Bind().
 //
 DEFINE_EVENT_TYPE(EVT_TRACKLIST_PERMUTED);
 DEFINE_EVENT_TYPE(EVT_TRACKLIST_RESIZING);

src/TrackPanel.cpp

@@ -360,20 +360,6 @@ TrackPanel::~TrackPanel()
 {
    mTimer.Stop();
 
-   // Unregister for tracklist updates
-   mTracks->Disconnect(EVT_TRACKLIST_DELETION,
-                       wxCommandEventHandler(TrackPanel::OnTrackListDeletion),
-                       NULL,
-                       this);
-   mTracks->Disconnect(EVT_TRACKLIST_RESIZING,
-                       wxCommandEventHandler(TrackPanel::OnTrackListResizing),
-                       NULL,
-                       this);
-   wxTheApp->Disconnect(EVT_AUDIOIO_PLAYBACK,
-                        wxCommandEventHandler(TrackPanel::OnPlayback),
-                        NULL,
-                        this);
-
    // This can happen if a label is being edited and the user presses
    // ALT+F4 or Command+Q
    if (HasCapture())

src/TranslatableStringArray.h

@@ -43,15 +43,6 @@ public:
             this);
    }
 
-   ~TranslatableArray()
-   {
-      if (wxTheApp)
-         wxTheApp->Disconnect(EVT_LANGUAGE_CHANGE,
-            wxCommandEventHandler(TranslatableArray::Invalidate),
-            NULL,
-            this);
-   }
-
    const ArrayType& Get()
    {
       if (mContents.empty())

src/effects/Contrast.cpp

@@ -307,14 +307,6 @@ ContrastDialog::ContrastDialog(wxWindow * parent, wxWindowID id,
    Center();
 }
 
-ContrastDialog::~ContrastDialog()
-{
-   mForegroundRMSText->Disconnect(wxEVT_KEY_DOWN, wxKeyEventHandler(ContrastDialog::OnChar));
-   mBackgroundRMSText->Disconnect(wxEVT_KEY_DOWN, wxKeyEventHandler(ContrastDialog::OnChar));
-   mPassFailText->Disconnect(wxEVT_KEY_DOWN, wxKeyEventHandler(ContrastDialog::OnChar));
-   mDiffText->Disconnect(wxEVT_KEY_DOWN, wxKeyEventHandler(ContrastDialog::OnChar));
-}
-
 void ContrastDialog::OnGetURL(wxCommandEvent & WXUNUSED(event))
 {
    // Original help page is back on-line (March 2016), but the manual should be more reliable.

src/effects/Contrast.h

@@ -32,7 +32,6 @@ public:
    // constructors and destructors
    ContrastDialog(wxWindow * parent, wxWindowID id,
               const wxString & title, const wxPoint & pos);
-   ~ContrastDialog();
 
    wxButton * m_pButton_UseCurrentF;
    wxButton * m_pButton_UseCurrentB;

src/effects/Effect.cpp

@@ -3845,16 +3845,6 @@ void EffectUIHost::CleanupRealtime()
 {
    if (mSupportsRealtime && mInitialized)
    {
-      wxTheApp->Disconnect(EVT_AUDIOIO_PLAYBACK,
-                           wxCommandEventHandler(EffectUIHost::OnPlayback),
-                           NULL,
-                           this);
-
-      wxTheApp->Disconnect(EVT_AUDIOIO_CAPTURE,
-                           wxCommandEventHandler(EffectUIHost::OnCapture),
-                           NULL,
-                           this);
-
       EffectManager::Get().RealtimeRemoveEffect(mEffect);
 
       mInitialized = false;

src/prefs/KeyConfigPrefs.cpp

@@ -89,37 +89,6 @@ KeyConfigPrefs::KeyConfigPrefs(wxWindow * parent, wxWindowID winid,
    }
 }
 
-KeyConfigPrefs::~KeyConfigPrefs()
-{
-   if (mKey)
-   {
-      mKey->Disconnect(wxEVT_KEY_DOWN,
-            wxKeyEventHandler(KeyConfigPrefs::OnHotkeyKeyDown),
-            NULL,
-            this);
-      mKey->Disconnect(wxEVT_CHAR,
-            wxKeyEventHandler(KeyConfigPrefs::OnHotkeyChar),
-            NULL,
-            this);
-      mKey->Disconnect(wxEVT_KILL_FOCUS,
-            wxFocusEventHandler(KeyConfigPrefs::OnHotkeyKillFocus),
-            NULL,
-            this);
-   }
-
-   if (mFilter)
-   {
-      mKey->Disconnect(wxEVT_KEY_DOWN,
-            wxKeyEventHandler(KeyConfigPrefs::OnFilterKeyDown),
-            NULL,
-            this);
-      mKey->Disconnect(wxEVT_CHAR,
-            wxKeyEventHandler(KeyConfigPrefs::OnFilterChar),
-            NULL,
-            this);
-   }
-}
-
 void KeyConfigPrefs::Populate()
 {
    ShuttleGui S(this, eIsCreatingFromPrefs);

src/prefs/KeyConfigPrefs.h

@@ -36,7 +36,6 @@ class KeyConfigPrefs final : public PrefsPanel
 {
 public:
    KeyConfigPrefs(wxWindow * parent, wxWindowID winid, const wxString &name);
-   ~KeyConfigPrefs();
    bool Commit() override;
    void Cancel() override;
    wxString HelpPageName() override;

src/toolbars/ToolManager.cpp

@@ -458,30 +458,6 @@ ToolManager::~ToolManager()
    // crashing when running with Jaws on Windows 10 1703.
    mTopDock->GetConfiguration().Clear();
    mBotDock->GetConfiguration().Clear();
-
-   // Remove handlers from parent
-   mParent->Disconnect( wxEVT_LEFT_UP,
-                        wxMouseEventHandler( ToolManager::OnMouse ),
-                        NULL,
-                        this );
-   mParent->Disconnect( wxEVT_MOTION,
-                        wxMouseEventHandler( ToolManager::OnMouse ),
-                        NULL,
-                        this );
-   mParent->Disconnect( wxEVT_MOUSE_CAPTURE_LOST,
-                        wxMouseCaptureLostEventHandler( ToolManager::OnCaptureLost ),
-                        NULL,
-                        this );
-
-   // Remove our event handlers
-   mIndicator->Disconnect( wxEVT_CREATE,
-                           wxWindowCreateEventHandler( ToolManager::OnIndicatorCreate ),
-                           NULL,
-                           this );
-   mIndicator->Disconnect( wxEVT_PAINT,
-                           wxPaintEventHandler( ToolManager::OnIndicatorPaint ),
-                           NULL,
-                           this );
 }
 
 // This table describes the default configuration of the toolbars as

src/tracks/ui/PlayIndicatorOverlay.cpp

@@ -117,11 +117,6 @@ PlayIndicatorOverlay::~PlayIndicatorOverlay()
       if(ruler)
          ruler->RemoveOverlay(mPartner.get());
    }
-
-   mProject->Disconnect(EVT_TRACK_PANEL_TIMER,
-                        wxCommandEventHandler(PlayIndicatorOverlay::OnTimer),
-                        NULL,
-                        this);
 }
 
 void PlayIndicatorOverlay::OnTimer(wxCommandEvent &event)

src/tracks/ui/Scrubbing.cpp

@@ -212,10 +212,6 @@ Scrubber::~Scrubber()
 #endif
 
    mProject->PopEventHandler();
-   if (wxTheApp)
-      wxTheApp->Disconnect
-      (wxEVT_ACTIVATE_APP,
-      wxActivateEventHandler(Scrubber::OnActivateOrDeactivateApp), NULL, this);
 }
 
 namespace {
@@ -736,14 +732,6 @@ ScrubbingOverlay::ScrubbingOverlay(AudacityProject *project)
       this);
 }
 
-ScrubbingOverlay::~ScrubbingOverlay()
-{
-   mProject->Disconnect(EVT_TRACK_PANEL_TIMER,
-      wxCommandEventHandler(ScrubbingOverlay::OnTimer),
-      NULL,
-      this);
-}
-
 std::pair<wxRect, bool> ScrubbingOverlay::DoGetRectangle(wxSize)
 {
    wxRect rect(mLastScrubRect);

src/tracks/ui/Scrubbing.h

@@ -209,7 +209,6 @@ class ScrubbingOverlay final : public wxEvtHandler, public Overlay
 {
 public:
    ScrubbingOverlay(AudacityProject *project);
-   virtual ~ScrubbingOverlay();
 
 private:
    std::pair<wxRect, bool> DoGetRectangle(wxSize size) override;

src/tracks/ui/SelectHandle.cpp

@@ -1048,15 +1048,6 @@ public:
             this);
    }
 
-   ~TimerHandler()
-   {
-      if (mConnectedProject)
-         mConnectedProject->Disconnect(EVT_TRACK_PANEL_TIMER,
-            wxCommandEventHandler(SelectHandle::TimerHandler::OnTimer),
-            NULL,
-            this);
-   }
-
    // Receives timer event notifications, to implement auto-scroll
    void OnTimer(wxCommandEvent &event);
 

src/widgets/Meter.cpp

@@ -340,35 +340,6 @@ void MeterPanel::Clear()
    mQueue.Clear();
 }
 
-MeterPanel::~MeterPanel()
-{
-   if (mIsInput)
-   {
-      // Unregister for AudioIO events
-      wxTheApp->Disconnect(EVT_AUDIOIO_MONITOR,
-                           wxCommandEventHandler(MeterPanel::OnAudioIOStatus),
-                           NULL,
-                           this);
-      wxTheApp->Disconnect(EVT_AUDIOIO_CAPTURE,
-                           wxCommandEventHandler(MeterPanel::OnAudioIOStatus),
-                           NULL,
-                           this);
-   }
-   else
-   {
-      wxTheApp->Disconnect(EVT_AUDIOIO_PLAYBACK,
-                           wxCommandEventHandler(MeterPanel::OnAudioIOStatus),
-                           NULL,
-                           this);
-   }
-
-   // Unregister for our preference update event
-   wxTheApp->Disconnect(EVT_METER_PREFERENCES_CHANGED,
-                        wxCommandEventHandler(MeterPanel::OnMeterPrefsUpdated),
-                        NULL,
-                        this);
-}
-
 void MeterPanel::UpdatePrefs()
 {
    mDBRange = gPrefs->Read(ENV_DB_KEY, ENV_DB_RANGE);

src/widgets/Meter.h

@@ -114,8 +114,6 @@ class MeterPanel final : public wxPanelWrapper
          Style style = HorizontalStereo,
          float fDecayRate = 60.0f);
 
-   ~MeterPanel();
-
    bool AcceptsFocus() const override { return s_AcceptsFocus; }
    bool AcceptsFocusFromKeyboard() const override { return true; }
 

src/widgets/PopupMenuTable.cpp

@@ -13,6 +13,8 @@ Paul Licameli split from TrackPanel.cpp
 
 PopupMenuTable::Menu::~Menu()
 {
+   // Event connections between the parent window and the singleton table
+   // object must be broken when this menu is destroyed.
    Disconnect();
 }
 

src/widgets/Ruler.cpp

@@ -2031,11 +2031,6 @@ AdornedRulerPanel::~AdornedRulerPanel()
 {
    if(HasCapture())
       ReleaseMouse();
-
-   wxTheApp->Disconnect(EVT_AUDIOIO_CAPTURE,
-                        wxCommandEventHandler(AdornedRulerPanel::OnCapture),
-                        NULL,
-                        this);
 }
 
 #if 1

src/widgets/wxPanelWrapper.h

@@ -27,11 +27,6 @@ public:
    {
       this->Bind(wxEVT_CHAR_HOOK, wxTabTraversalWrapperCharHook);
    }
-
-   ~wxTabTraversalWrapper()
-   {
-      this->Unbind(wxEVT_CHAR_HOOK, wxTabTraversalWrapperCharHook);
-   }
 };
 
 class AUDACITY_DLL_API wxPanelWrapper : public wxTabTraversalWrapper<wxPanel>