Simplify the FN macros in src/menus/*.cpp...

... Eliminate repetitious passing of the finder function into each of the
calls to Command and CommandGroup.

lib-src/mod-null/ModNullCallback.cpp

@@ -113,7 +113,7 @@ void ModNullCallback::OnFuncSecond(const CommandContext &)
 }
 ModNullCallback * pModNullCallback=NULL;
 
-#define ModNullFN(X) ident, static_cast<CommandFunctorPointer>(&ModNullCallback:: X)
+#define ModNullFN(X) static_cast<CommandFunctorPointer>((&ModNullCallback:: X))
 
 extern "C" {
 
@@ -163,12 +163,12 @@ int ModuleDispatch(ModuleDispatchTypes type)
          c->AddItem( 
             _T("A New Command"), // internal name
             XO("1st Experimental Command..."), //displayed name
-            ModNullFN( OnFuncFirst ),
+            ident, ModNullFN( OnFuncFirst ),
             AudioIONotBusyFlag );
          c->AddItem( 
             _T("Another New Command"),
             XO("2nd Experimental Command"),
-            ModNullFN( OnFuncSecond ),
+            ident, ModNullFN( OnFuncSecond ),
             AudioIONotBusyFlag );
          c->ClearCurrentMenu();
    }

src/Menus.cpp

@@ -134,10 +134,10 @@ SeparatorItem::~SeparatorItem() {}
 
 CommandItem::CommandItem(const CommandID &name_,
          const TranslatableString &label_in_,
-         CommandHandlerFinder finder_,
          CommandFunctorPointer callback_,
          CommandFlag flags_,
-         const CommandManager::Options &options_)
+         const CommandManager::Options &options_,
+         CommandHandlerFinder finder_)
 : name{ name_ }, label_in{ label_in_ }
 , finder{ finder_ }, callback{ callback_ }
 , flags{ flags_ }, options{ options_ }
@@ -146,10 +146,10 @@ CommandItem::~CommandItem() {}
 
 CommandGroupItem::CommandGroupItem(const wxString &name_,
          std::initializer_list< ComponentInterfaceSymbol > items_,
-         CommandHandlerFinder finder_,
          CommandFunctorPointer callback_,
          CommandFlag flags_,
-         bool isEffect_)
+         bool isEffect_,
+         CommandHandlerFinder finder_)
 : name{ name_ }, items{ items_ }
 , finder{ finder_ }, callback{ callback_ }
 , flags{ flags_ }, isEffect{ isEffect_ }
@@ -158,6 +158,15 @@ CommandGroupItem::~CommandGroupItem() {}
 
 SpecialItem::~SpecialItem() {}
 
+CommandHandlerFinder FinderScope::sFinder =
+   [](AudacityProject &project) -> CommandHandlerObject & {
+      // If this default finder function is reached, then FinderScope should
+      // have been used somewhere, or an explicit CommandHandlerFinder passed
+      // to menu item constructors
+      wxASSERT( false );
+      return project;
+   };
+
 }
 
 namespace {

src/commands/CommandManager.h

@@ -490,13 +490,57 @@ namespace MenuTable {
       ~SeparatorItem() override;
    };
 
+   // usage:
+   //   auto scope = FinderScope( findCommandHandler );
+   //   return Items( ... );
+   //
+   // or:
+   //   return FinderScope( findCommandHandler )
+   //      .Eval( Items( ... ) );
+   //
+   // where findCommandHandler names a function.
+   // This is used before a sequence of many calls to Command() and
+   // CommandGroup(), so that the finder argument need not be specified
+   // in each call.
+   class FinderScope : ValueRestorer< CommandHandlerFinder >
+   {
+      static CommandHandlerFinder sFinder;
+
+   public:
+      static CommandHandlerFinder DefaultFinder() { return sFinder; }
+
+      explicit
+      FinderScope( CommandHandlerFinder finder )
+         : ValueRestorer( sFinder, finder )
+      {}
+
+      // See usage comment above about this pass-through function
+      template< typename Value > Value&& Eval( Value &&value ) const
+         { return std::forward<Value>(value); }
+   };
+
    struct CommandItem final : BaseItem {
       CommandItem(const CommandID &name_,
                const TranslatableString &label_in_,
-               CommandHandlerFinder finder_,
                CommandFunctorPointer callback_,
                CommandFlag flags_,
-               const CommandManager::Options &options_);
+               const CommandManager::Options &options_,
+               CommandHandlerFinder finder_);
+
+      // Takes a pointer to member function directly, and delegates to the
+      // previous constructor; useful within the lifetime of a FinderScope
+      template< typename Handler >
+      CommandItem(const CommandID &name_,
+               const TranslatableString &label_in_,
+               void (Handler::*pmf)(const CommandContext&),
+               CommandFlag flags_,
+               const CommandManager::Options &options_,
+               CommandHandlerFinder finder = FinderScope::DefaultFinder())
+         : CommandItem(name_, label_in_,
+            static_cast<CommandFunctorPointer>(pmf),
+            flags_, options_, finder)
+      {}
+
       ~CommandItem() override;
 
       const CommandID name;
@@ -510,10 +554,25 @@ namespace MenuTable {
    struct CommandGroupItem final : BaseItem {
       CommandGroupItem(const wxString &name_,
                std::initializer_list< ComponentInterfaceSymbol > items_,
-               CommandHandlerFinder finder_,
                CommandFunctorPointer callback_,
                CommandFlag flags_,
-               bool isEffect_);
+               bool isEffect_,
+               CommandHandlerFinder finder_);
+
+      // Takes a pointer to member function directly, and delegates to the
+      // previous constructor; useful within the lifetime of a FinderScope
+      template< typename Handler >
+      CommandGroupItem(const wxString &name_,
+               std::initializer_list< ComponentInterfaceSymbol > items_,
+               void (Handler::*pmf)(const CommandContext&),
+               CommandFlag flags_,
+               bool isEffect_,
+               CommandHandlerFinder finder = FinderScope::DefaultFinder())
+         : CommandGroupItem(name_, items_,
+            static_cast<CommandFunctorPointer>(pmf),
+            flags_, isEffect_, finder)
+      {}
+
       ~CommandGroupItem() override;
 
       const wxString name;
@@ -588,25 +647,29 @@ namespace MenuTable {
    inline std::unique_ptr<SeparatorItem> Separator()
       { return std::make_unique<SeparatorItem>(); }
 
+   template< typename Handler >
    inline std::unique_ptr<CommandItem> Command(
       const CommandID &name,
       const TranslatableString &label_in,
-      CommandHandlerFinder finder, CommandFunctorPointer callback,
+      void (Handler::*pmf)(const CommandContext&),
-      CommandFlag flags, const CommandManager::Options &options = {})
+      CommandFlag flags, const CommandManager::Options &options = {},
+      CommandHandlerFinder finder = FinderScope::DefaultFinder())
    {
       return std::make_unique<CommandItem>(
-         name, label_in, finder, callback, flags, options
+         name, label_in, pmf, flags, options, finder
       );
    }
 
+   template< typename Handler >
    inline std::unique_ptr<CommandGroupItem> CommandGroup(
       const wxString &name,
       std::initializer_list< ComponentInterfaceSymbol > items,
-      CommandHandlerFinder finder, CommandFunctorPointer callback,
+      void (Handler::*pmf)(const CommandContext&),
-      CommandFlag flags, bool isEffect = false)
+      CommandFlag flags, bool isEffect = false,
+      CommandHandlerFinder finder = FinderScope::DefaultFinder())
    {
       return std::make_unique<CommandGroupItem>(
-         name, items, finder, callback, flags, isEffect
+         name, items, pmf, flags, isEffect, finder
       );
    }
 

src/menus/ClipMenus.cpp

@@ -821,15 +821,15 @@ static CommandHandlerObject &findCommandHandler(AudacityProject &) {
 
 // Menu definitions
 
-#define FN(X) findCommandHandler, \
+#define FN(X) (& ClipActions::Handler :: X)
-   static_cast<CommandFunctorPointer>(& ClipActions::Handler :: X)
 
 MenuTable::BaseItemPtr ClipSelectMenu( AudacityProject& )
 {
    using namespace MenuTable;
    using Options = CommandManager::Options;
 
-   return Menu( XO("Clip B&oundaries"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("Clip B&oundaries"),
       Command( wxT("SelPrevClipBoundaryToCursor"),
          XXO("Pre&vious Clip Boundary to Cursor"),
          FN(OnSelectPrevClipBoundaryToCursor),
@@ -844,7 +844,7 @@ MenuTable::BaseItemPtr ClipSelectMenu( AudacityProject& )
       Command( wxT("SelNextClip"), XXO("N&ext Clip"), FN(OnSelectNextClip),
          WaveTracksExistFlag,
          Options{ wxT("Alt+."), XO("Select Next Clip") } )
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ClipCursorItems( AudacityProject & )
@@ -852,7 +852,8 @@ MenuTable::BaseItemPtr ClipCursorItems( AudacityProject & )
    using namespace MenuTable;
    using Options = CommandManager::Options;
 
-   return Items(
+   return FinderScope( findCommandHandler ).Eval(
+   Items(
       Command( wxT("CursPrevClipBoundary"), XXO("Pre&vious Clip Boundary"),
          FN(OnCursorPrevClipBoundary),
          WaveTracksExistFlag,
@@ -861,19 +862,20 @@ MenuTable::BaseItemPtr ClipCursorItems( AudacityProject & )
          FN(OnCursorNextClipBoundary),
          WaveTracksExistFlag,
          Options{}.LongName( XO("Cursor to Next Clip Boundary") ) )
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraClipCursorItems( AudacityProject & )
 {
    using namespace MenuTable;
 
-   return Items(
+   return FinderScope( findCommandHandler ).Eval(
+   Items(
       Command( wxT("ClipLeft"), XXO("Clip L&eft"), FN(OnClipLeft),
          TracksExistFlag | TrackPanelHasFocus, wxT("\twantKeyup") ),
       Command( wxT("ClipRight"), XXO("Clip Rig&ht"), FN(OnClipRight),
          TracksExistFlag | TrackPanelHasFocus, wxT("\twantKeyup") )
-   );
+   ) );
 }
 
 #undef FN

src/menus/EditMenus.cpp

@@ -995,8 +995,7 @@ static CommandHandlerObject &findCommandHandler(AudacityProject &) {
 
 // Menu definitions
 
-#define FN(X) findCommandHandler, \
+#define FN(X) (& EditActions::Handler :: X)
-   static_cast<CommandFunctorPointer>(& EditActions::Handler :: X)
 
 MenuTable::BaseItemPtr LabelEditMenus( AudacityProject &project );
 
@@ -1052,7 +1051,8 @@ MenuTable::BaseItemPtr EditMenu( AudacityProject & )
 #endif
    ;
 
-   return Menu( XO("&Edit"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&Edit"),
       Command( wxT("Undo"), XXO("&Undo"), FN(OnUndo),
          AudioIONotBusyFlag | UndoAvailableFlag, wxT("Ctrl+Z") ),
 
@@ -1145,7 +1145,7 @@ MenuTable::BaseItemPtr EditMenu( AudacityProject & )
 
       Command( wxT("Preferences"), XXO("Pre&ferences..."), FN(OnPreferences),
          AudioIONotBusyFlag, prefKey )
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraEditMenu( AudacityProject & )
@@ -1154,14 +1154,16 @@ MenuTable::BaseItemPtr ExtraEditMenu( AudacityProject & )
    using Options = CommandManager::Options;
    static const auto flags =
       AudioIONotBusyFlag | TracksSelectedFlag | TimeSelectedFlag;
-   return Menu( XO("&Edit"),
+
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&Edit"),
       Command( wxT("DeleteKey"), XXO("&Delete Key"), FN(OnDelete),
          (flags | NoAutoSelect),
          wxT("Backspace") ),
       Command( wxT("DeleteKey2"), XXO("Delete Key&2"), FN(OnDelete),
          (flags | NoAutoSelect),
          wxT("Delete") )
-   );
+   ) );
 }
 
 auto canSelectAll = [](const AudacityProject &project){

src/menus/ExtraMenus.cpp

@@ -134,8 +134,7 @@ static CommandHandlerObject &findCommandHandler(AudacityProject &) {
 
 // Menu definitions
 
-#define FN(X) findCommandHandler, \
+#define FN(X) (& ExtraActions::Handler :: X)
-   static_cast<CommandFunctorPointer>(& ExtraActions::Handler :: X)
 
 // Imported menu item definitions
 
@@ -193,7 +192,9 @@ MenuTable::BaseItemPtr ExtraMenu( AudacityProject & )
 MenuTable::BaseItemPtr ExtraMixerMenu( AudacityProject & )
 {
    using namespace MenuTable;
-   return Menu( XO("Mi&xer"),
+
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("Mi&xer"),
       Command( wxT("OutputGain"), XXO("Ad&just Playback Volume..."),
          FN(OnOutputGain), AlwaysEnabledFlag ),
       Command( wxT("OutputGainInc"), XXO("&Increase Playback Volume"),
@@ -206,13 +207,15 @@ MenuTable::BaseItemPtr ExtraMixerMenu( AudacityProject & )
          FN(OnInputGainInc), AlwaysEnabledFlag ),
       Command( wxT("InputGainDec"), XXO("D&ecrease Recording Volume"),
          FN(OnInputGainDec), AlwaysEnabledFlag )
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraDeviceMenu( AudacityProject & )
 {
    using namespace MenuTable;
-   return Menu( XO("De&vice"),
+
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("De&vice"),
       Command( wxT("InputDevice"), XXO("Change &Recording Device..."),
          FN(OnInputDevice),
          AudioIONotBusyFlag, wxT("Shift+I") ),
@@ -224,7 +227,7 @@ MenuTable::BaseItemPtr ExtraDeviceMenu( AudacityProject & )
       Command( wxT("InputChannels"), XXO("Change Recording Cha&nnels..."),
          FN(OnInputChannels),
          AudioIONotBusyFlag, wxT("Shift+N") )
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraMiscItems( AudacityProject &project )
@@ -241,7 +244,9 @@ MenuTable::BaseItemPtr ExtraMiscItems( AudacityProject &project )
    ;
 
    // Not a menu.
-   return Items(
+
+   return FinderScope( findCommandHandler ).Eval(
+   Items(
       // Accel key is not bindable.
       Command( wxT("FullScreenOnOff"), XXO("&Full Screen (on/off)"),
          FN(OnFullScreen),
@@ -250,7 +255,7 @@ MenuTable::BaseItemPtr ExtraMiscItems( AudacityProject &project )
             GetProjectFrame( project ).wxTopLevelWindow::IsFullScreen() ) ),
 
       ExtraWindowItems
-   );
+   ) );
 }
 
 #undef FN

src/menus/FileMenus.cpp

@@ -549,15 +549,15 @@ static CommandHandlerObject &findCommandHandler(AudacityProject &) {
 
 // Menu definitions
 
-#define FN(X) findCommandHandler, \
+#define FN(X) (& FileActions::Handler :: X)
-   static_cast<CommandFunctorPointer>(& FileActions::Handler :: X)
 
 MenuTable::BaseItemPtr FileMenu( AudacityProject& )
 {
    using namespace MenuTable;
    using Options = CommandManager::Options;
 
-   return Menu( XO("&File"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&File"),
       /*i18n-hint: "New" is an action (verb) to create a NEW project*/
       Command( wxT("New"), XXO("&New"), FN(OnNew),
          AudioIONotBusyFlag, wxT("Ctrl+N") ),
@@ -698,7 +698,7 @@ MenuTable::BaseItemPtr FileMenu( AudacityProject& )
       /* i18n-hint: (verb) It's item on a menu. */
       Command( wxT("Exit"), XXO("E&xit"), FN(OnExit),
          AlwaysEnabledFlag, wxT("Ctrl+Q") )
-   );
+   ) );
 }
 
 #undef FN

src/menus/HelpMenus.cpp

@@ -418,8 +418,7 @@ static CommandHandlerObject &findCommandHandler(AudacityProject &) {
 
 // Menu definitions
 
-#define FN(X) findCommandHandler, \
+#define FN(X) (& HelpActions::Handler :: X)
-   static_cast<CommandFunctorPointer>(& HelpActions::Handler :: X)
 
 MenuTable::BaseItemPtr HelpMenu( AudacityProject & )
 {
@@ -429,7 +428,8 @@ MenuTable::BaseItemPtr HelpMenu( AudacityProject & )
 
    using namespace MenuTable;
 
-   return Menu( XO("&Help"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&Help"),
       // QuickFix menu item not in Audacity 2.3.1 whilst we discuss further.
 #ifdef EXPERIMENTAL_DA
       // DA: Has QuickFix menu item.
@@ -480,7 +480,7 @@ MenuTable::BaseItemPtr HelpMenu( AudacityProject & )
 #endif
       Command( wxT("About"), XXO("&About Audacity..."), FN(OnAbout),
          AlwaysEnabledFlag )
-   );
+   ) );
 }
 
 #undef FN

src/menus/LabelMenus.cpp

@@ -559,8 +559,7 @@ static CommandHandlerObject &findCommandHandler(AudacityProject &) {
 
 // Menu definitions
 
-#define FN(X) findCommandHandler, \
+#define FN(X) (& LabelEditActions::Handler :: X)
-   static_cast<CommandFunctorPointer>(& LabelEditActions::Handler :: X)
 
 MenuTable::BaseItemPtr LabelEditMenus( AudacityProject & )
 {
@@ -575,7 +574,9 @@ MenuTable::BaseItemPtr LabelEditMenus( AudacityProject & )
 
    // Returns TWO menus.
    
-   return Items(
+
+   return FinderScope( findCommandHandler ).Eval(
+   Items(
 
    Menu( XO("&Labels"),
       Command( wxT("EditLabels"), XXO("&Edit Labels..."), FN(OnEditLabels),
@@ -653,7 +654,7 @@ MenuTable::BaseItemPtr LabelEditMenus( AudacityProject & )
          wxT("Alt+Shift+J") )
    ) // second menu
 
-   ); // two menus
+   ) ); // two menus
 }
 
 #undef FN

src/menus/NavigationMenus.cpp

@@ -553,22 +553,23 @@ static CommandHandlerObject &findCommandHandler(AudacityProject &project) {
 
 // Menu definitions
 
-#define FN(X) findCommandHandler, \
+#define FN(X) (& NavigationActions::Handler :: X)
-   static_cast<CommandFunctorPointer>(& NavigationActions::Handler :: X)
 
 MenuTable::BaseItemPtr ExtraGlobalCommands( AudacityProject & )
 {
    // Ceci n'est pas un menu
    using namespace MenuTable;
    using Options = CommandManager::Options;
-   return Items(
+
+   return FinderScope( findCommandHandler ).Eval(
+   Items(
       Command( wxT("PrevWindow"), XXO("Move Backward Through Active Windows"),
          FN(OnPrevWindow), AlwaysEnabledFlag,
          Options{ wxT("Alt+Shift+F6") }.IsGlobal() ),
       Command( wxT("NextWindow"), XXO("Move Forward Through Active Windows"),
          FN(OnNextWindow), AlwaysEnabledFlag,
          Options{ wxT("Alt+F6") }.IsGlobal() )
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraFocusMenu( AudacityProject & )
@@ -576,7 +577,8 @@ MenuTable::BaseItemPtr ExtraFocusMenu( AudacityProject & )
    using namespace MenuTable;
    static const auto FocusedTracksFlags = TracksExistFlag | TrackPanelHasFocus;
 
-   return Menu( XO("F&ocus"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("F&ocus"),
       Command( wxT("PrevFrame"),
          XXO("Move &Backward from Toolbars to Tracks"), FN(OnPrevFrame),
          AlwaysEnabledFlag, wxT("Ctrl+Shift+F6") ),
@@ -599,7 +601,7 @@ MenuTable::BaseItemPtr ExtraFocusMenu( AudacityProject & )
          FocusedTracksFlags, wxT("Return") ),
       Command( wxT("ToggleAlt"), XXO("Toggle Focuse&d Track"), FN(OnToggle),
          FocusedTracksFlags, wxT("NUMPAD_ENTER") )
-   );
+   ) );
 }
 
 #undef FN

src/menus/PluginMenus.cpp

@@ -585,8 +585,7 @@ static CommandHandlerObject &findCommandHandler(AudacityProject &) {
 
 // Menu definitions? ...
 
-#define FN(X) findCommandHandler, \
+#define FN(X) (& PluginActions::Handler :: X)
-   static_cast<CommandFunctorPointer>(& PluginActions::Handler :: X)
 
 // ... buf first some more helper definitions, which use FN
 namespace {
@@ -632,6 +631,8 @@ void AddEffectMenuItemGroup(
    }
 
    using namespace MenuTable;
+   // This finder scope may be redundant, but harmless
+   auto scope = FinderScope( findCommandHandler );
    auto pTable = &table;
    BaseItemPtrs temp1;
 
@@ -721,6 +722,8 @@ MenuTable::BaseItemPtrs PopulateMacrosMenu( CommandFlag flags  )
    auto names = MacroCommands::GetNames(); // these names come from filenames
    int i;
 
+   // This finder scope may be redundant, but harmless
+   auto scope = MenuTable::FinderScope( findCommandHandler );
    for (i = 0; i < (int)names.size(); i++) {
       auto MacroID = ApplyMacroDialog::MacroIdOfName( names[i] );
       result.push_back( MenuTable::Command( MacroID,
@@ -744,7 +747,8 @@ MenuTable::BaseItemPtr GenerateMenu( AudacityProject & )
    // All of this is a bit hacky until we can get more things connected into
    // the plugin manager...sorry! :-(
 
-   return Menu( XO("&Generate"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&Generate"),
 #ifdef EXPERIMENTAL_EFFECT_MANAGEMENT
       Command( wxT("ManageGenerators"), XXO("Add / Remove Plug-ins..."),
          FN(OnManageGenerators), AudioIONotBusyFlag ),
@@ -757,7 +761,7 @@ MenuTable::BaseItemPtr GenerateMenu( AudacityProject & )
          EffectTypeGenerate,
          AudioIONotBusyFlag,
          AudioIONotBusyFlag) )
-   );
+   ) );
 }
 
 const ReservedCommandFlag
@@ -781,7 +785,8 @@ MenuTable::BaseItemPtr EffectMenu( AudacityProject &project )
    else
       buildMenuLabel = XO("Repeat Last Effect");
 
-   return Menu( XO("Effe&ct"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("Effe&ct"),
 #ifdef EXPERIMENTAL_EFFECT_MANAGEMENT
       Command( wxT("ManageEffects"), XXO("Add / Remove Plug-ins..."),
          FN(OnManageEffects), AudioIONotBusyFlag ),
@@ -801,7 +806,7 @@ MenuTable::BaseItemPtr EffectMenu( AudacityProject &project )
          EffectTypeProcess,
          AudioIONotBusyFlag | TimeSelectedFlag | WaveTracksSelectedFlag,
          IsRealtimeNotActiveFlag ) )
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr AnalyzeMenu( AudacityProject & )
@@ -810,7 +815,8 @@ MenuTable::BaseItemPtr AnalyzeMenu( AudacityProject & )
    // All of this is a bit hacky until we can get more things connected into
    // the plugin manager...sorry! :-(
 
-   return Menu( XO("&Analyze"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&Analyze"),
 #ifdef EXPERIMENTAL_EFFECT_MANAGEMENT
       Command( wxT("ManageAnalyzers"), XXO("Add / Remove Plug-ins..."),
          FN(OnManageAnalyzers), AudioIONotBusyFlag ),
@@ -829,7 +835,7 @@ MenuTable::BaseItemPtr AnalyzeMenu( AudacityProject & )
          EffectTypeAnalyze,
          AudioIONotBusyFlag | TimeSelectedFlag | WaveTracksSelectedFlag,
          IsRealtimeNotActiveFlag ) )
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ToolsMenu( AudacityProject & )
@@ -838,7 +844,8 @@ MenuTable::BaseItemPtr ToolsMenu( AudacityProject & )
    using Options = CommandManager::Options;
    auto gAudioIO = AudioIO::Get();
 
-   return Menu( XO("T&ools"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("T&ools"),
 
 #ifdef EXPERIMENTAL_EFFECT_MANAGEMENT
       Command( wxT("ManageTools"), XXO("Add / Remove Plug-ins..."),
@@ -899,7 +906,7 @@ MenuTable::BaseItemPtr ToolsMenu( AudacityProject & )
          AudioIONotBusyFlag,
          Options{}.CheckState( gAudioIO->mDetectUpstreamDropouts ) )
 #endif
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraScriptablesIMenu( AudacityProject & )
@@ -907,8 +914,10 @@ MenuTable::BaseItemPtr ExtraScriptablesIMenu( AudacityProject & )
    using namespace MenuTable;
 
    // These are the more useful to VI user Scriptables.
+
+   return FinderScope( findCommandHandler ).Eval(
    // i18n-hint: Scriptables are commands normally used from Python, Perl etc.
-   return Menu( XO("Script&ables I"),
+   Menu( XO("Script&ables I"),
       // Note that the PLUGIN_SYMBOL must have a space between words, 
       // whereas the short-form used here must not.
       // (So if you did write "CompareAudio" for the PLUGIN_SYMBOL name, then
@@ -945,7 +954,7 @@ MenuTable::BaseItemPtr ExtraScriptablesIMenu( AudacityProject & )
          AudioIONotBusyFlag ),
       Command( wxT("SetProject"), XXO("Set Project..."), FN(OnAudacityCommand),
          AudioIONotBusyFlag )
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraScriptablesIIMenu( AudacityProject & )
@@ -953,7 +962,8 @@ MenuTable::BaseItemPtr ExtraScriptablesIIMenu( AudacityProject & )
    using namespace MenuTable;
 
    // Less useful to VI users.
-   return Menu( XO("Scripta&bles II"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("Scripta&bles II"),
       Command( wxT("Select"), XXO("Select..."), FN(OnAudacityCommand),
          AudioIONotBusyFlag ),
       Command( wxT("SetTrack"), XXO("Set Track..."), FN(OnAudacityCommand),
@@ -983,7 +993,7 @@ MenuTable::BaseItemPtr ExtraScriptablesIIMenu( AudacityProject & )
       Command( wxT("Screenshot"), XXO("Screenshot (short format)..."),
          FN(OnAudacityCommand),
          AudioIONotBusyFlag )
-   );
+   ) );
 }
 
 #undef FN

src/menus/SelectMenus.cpp

@@ -1026,8 +1026,7 @@ static CommandHandlerObject &findCommandHandler(AudacityProject &project) {
 
 // Menu definitions
 
-#define FN(X) findCommandHandler, \
+#define FN(X) (& SelectActions::Handler :: X)
-   static_cast<CommandFunctorPointer>(& SelectActions::Handler :: X)
 
 MenuTable::BaseItemPtr ClipSelectMenu( AudacityProject& );
 
@@ -1036,8 +1035,9 @@ MenuTable::BaseItemPtr SelectMenu( AudacityProject& )
    using namespace MenuTable;
    using Options = CommandManager::Options;
 
+   return FinderScope( findCommandHandler ).Eval(
    /* i18n-hint: (verb) It's an item on a menu. */
-   return Menu( XO("&Select"),
+   Menu( XO("&Select"),
       Command( wxT("SelectAll"), XXO("&All"), FN(OnSelectAll),
          TracksExistFlag,
          Options{ wxT("Ctrl+A"), XO("Select All") } ),
@@ -1135,13 +1135,15 @@ MenuTable::BaseItemPtr SelectMenu( AudacityProject& )
       Command( wxT("ZeroCross"), XXO("At &Zero Crossings"),
          FN(OnZeroCrossing), TracksSelectedFlag,
          Options{ wxT("Z"), XO("Select Zero Crossing") } )
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraSelectionMenu( AudacityProject & )
 {
    using namespace MenuTable;
-   return Menu( XO("&Selection"),
+
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&Selection"),
       Command( wxT("SnapToOff"), XXO("Snap-To &Off"), FN(OnSnapToOff),
          AlwaysEnabledFlag ),
       Command( wxT("SnapToNearest"), XXO("Snap-To &Nearest"),
@@ -1174,7 +1176,7 @@ MenuTable::BaseItemPtr ExtraSelectionMenu( AudacityProject & )
          FN(OnSelContractRight),
          TracksExistFlag | TrackPanelHasFocus,
          wxT("Ctrl+Shift+Left\twantKeyup") )
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ClipCursorItems( AudacityProject & );
@@ -1190,7 +1192,8 @@ MenuTable::BaseItemPtr CursorMenu( AudacityProject & )
    // GA: 'Skip to' moves the viewpoint to center of the track and preserves the
    // selection. 'Cursor to' does neither. 'Center at' might describe it better
    // than 'Skip'.
-   return Menu( XO("&Cursor to"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&Cursor to"),
       Command( wxT("CursSelStart"), XXO("Selection Star&t"),
          FN(OnCursorSelStart),
          TimeSelectedFlag,
@@ -1218,7 +1221,7 @@ MenuTable::BaseItemPtr CursorMenu( AudacityProject & )
       Command( wxT("CursProjectEnd"), XXO("Project E&nd"), FN(OnSkipEnd),
          CanStopFlags,
          Options{ wxT("End"), XO("Cursor to Project End") } )
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraClipCursorItems( AudacityProject & );
@@ -1227,7 +1230,8 @@ MenuTable::BaseItemPtr ExtraCursorMenu( AudacityProject & )
 {
    using namespace MenuTable;
 
-   return Menu( XO("&Cursor"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&Cursor"),
       Command( wxT("CursorLeft"), XXO("Cursor &Left"), FN(OnCursorLeft),
          TracksExistFlag | TrackPanelHasFocus,
          wxT("Left\twantKeyup\tallowDup") ),
@@ -1248,13 +1252,15 @@ MenuTable::BaseItemPtr ExtraCursorMenu( AudacityProject & )
          TracksExistFlag | TrackPanelHasFocus, wxT("Shift+.") ),
 
       ExtraClipCursorItems
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraSeekMenu( AudacityProject & )
 {
    using namespace MenuTable;
-   return Menu( XO("See&k"),
+
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("See&k"),
       Command( wxT("SeekLeftShort"), XXO("Short Seek &Left During Playback"),
          FN(OnSeekLeftShort), AudioIOBusyFlag, wxT("Left\tallowDup") ),
       Command( wxT("SeekRightShort"),
@@ -1264,7 +1270,7 @@ MenuTable::BaseItemPtr ExtraSeekMenu( AudacityProject & )
          FN(OnSeekLeftLong), AudioIOBusyFlag, wxT("Shift+Left\tallowDup") ),
       Command( wxT("SeekRightLong"), XXO("Long Seek Rig&ht During Playback"),
          FN(OnSeekRightLong), AudioIOBusyFlag, wxT("Shift+Right\tallowDup") )
-   );
+   ) );
 }
 
 #undef FN

src/menus/ToolbarMenus.cpp

@@ -251,8 +251,7 @@ static CommandHandlerObject &findCommandHandler(AudacityProject &) {
 
 // Menu definitions
 
-#define FN(X) findCommandHandler, \
+#define FN(X) (& ToolbarActions::Handler :: X)
-   static_cast<CommandFunctorPointer>(& ToolbarActions::Handler :: X)
 
 MenuTable::BaseItemPtr ToolbarsMenu( AudacityProject& )
 {
@@ -261,7 +260,8 @@ MenuTable::BaseItemPtr ToolbarsMenu( AudacityProject& )
 
    static const auto checkOff = Options{}.CheckState( false );
 
-   return Menu( XO("&Toolbars"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&Toolbars"),
       /* i18n-hint: (verb)*/
       Command( wxT("ResetToolbars"), XXO("Reset Toolb&ars"),
          FN(OnResetToolBars), AlwaysEnabledFlag ),
@@ -330,13 +330,15 @@ MenuTable::BaseItemPtr ToolbarsMenu( AudacityProject& )
          XXO("Spe&ctral Selection Toolbar"),
          FN(OnShowSpectralSelectionToolBar), AlwaysEnabledFlag, checkOff )
 #endif
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraToolsMenu( AudacityProject & )
 {
    using namespace MenuTable;
-   return Menu( XO("T&ools"),
+
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("T&ools"),
       Command( wxT("SelectTool"), XXO("&Selection Tool"), FN(OnSelectTool),
          AlwaysEnabledFlag, wxT("F1") ),
       Command( wxT("EnvelopeTool"), XXO("&Envelope Tool"),
@@ -353,7 +355,7 @@ MenuTable::BaseItemPtr ExtraToolsMenu( AudacityProject & )
          AlwaysEnabledFlag, wxT("A") ),
       Command( wxT("NextTool"), XXO("&Next Tool"), FN(OnNextTool),
          AlwaysEnabledFlag, wxT("D") )
-   );
+   ) );
 }
 
 #undef FN

src/menus/TrackMenus.cpp

@@ -1274,8 +1274,7 @@ static CommandHandlerObject &findCommandHandler(AudacityProject &) {
 
 // Menu definitions
 
-#define FN(X) findCommandHandler, \
+#define FN(X) (& TrackActions::Handler :: X)
-   static_cast<CommandFunctorPointer>(& TrackActions::Handler :: X)
 
 MenuTable::BaseItemPtr TracksMenu( AudacityProject & )
 {
@@ -1283,7 +1282,8 @@ MenuTable::BaseItemPtr TracksMenu( AudacityProject & )
    using namespace MenuTable;
    using Options = CommandManager::Options;
 
-   return Menu( XO("&Tracks"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&Tracks"),
       Menu( XO("Add &New"),
          Command( wxT("NewMonoTrack"), XXO("&Mono Track"), FN(OnNewWaveTrack),
             AudioIONotBusyFlag, wxT("Ctrl+Shift+N") ),
@@ -1300,6 +1300,7 @@ MenuTable::BaseItemPtr TracksMenu( AudacityProject & )
       Separator(),
 
       Menu( XO("Mi&x"),
+         // Delayed evaluation
          // Stereo to Mono is an oddball command that is also subject to control
          // by the plug-in manager, as if an effect.  Decide whether to show or
          // hide it.
@@ -1311,7 +1312,7 @@ MenuTable::BaseItemPtr TracksMenu( AudacityProject & )
                return Command( wxT("Stereo to Mono"),
                   XXO("Mix Stereo Down to &Mono"), FN(OnStereoToMono),
                   AudioIONotBusyFlag | StereoRequiredFlag |
-                     WaveTracksSelectedFlag );
+                     WaveTracksSelectedFlag, Options{}, findCommandHandler );
             else
                return {};
          },
@@ -1427,14 +1428,15 @@ MenuTable::BaseItemPtr TracksMenu( AudacityProject & )
          Options{}.CheckState( gPrefs->Read(wxT("/GUI/SyncLockTracks"), 0L) ) )
 
 #endif
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraTrackMenu( AudacityProject & )
 {
    using namespace MenuTable;
 
-   return Menu( XO("&Track"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&Track"),
       Command( wxT("TrackPan"), XXO("Change P&an on Focused Track..."),
          FN(OnTrackPan),
          TrackPanelHasFocus | TracksExistFlag, wxT("Shift+P") ),
@@ -1478,7 +1480,7 @@ MenuTable::BaseItemPtr ExtraTrackMenu( AudacityProject & )
       Command( wxT("TrackMoveBottom"), XXO("Move Focused Track to &Bottom"),
          FN(OnTrackMoveBottom),
          AudioIONotBusyFlag | TrackPanelHasFocus | TracksExistFlag )
-   );
+   ) );
 }
 
 #undef FN

src/menus/TransportMenus.cpp

@@ -966,8 +966,7 @@ static CommandHandlerObject &findCommandHandler(AudacityProject &) {
 
 // Menu definitions
 
-#define FN(X) findCommandHandler, \
+#define FN(X) (& TransportActions::Handler :: X)
-   static_cast<CommandFunctorPointer>(& TransportActions::Handler :: X)
 
 MenuTable::BaseItemPtr CursorMenu( AudacityProject& );
 
@@ -981,9 +980,10 @@ MenuTable::BaseItemPtr TransportMenu( AudacityProject &project )
 
    static const auto CanStopFlags = AudioIONotBusyFlag | CanStopAudioStreamFlag;
 
+   return FinderScope( findCommandHandler ).Eval(
    /* i18n-hint: 'Transport' is the name given to the set of controls that
       play, record, pause etc. */
-   return Menu( XO("Tra&nsport"),
+   Menu( XO("Tra&nsport"),
       Menu( XO("Pl&aying"),
          /* i18n-hint: (verb) Start or Stop audio playback*/
          Command( wxT("PlayStop"), XXO("Pl&ay/Stop"), FN(OnPlayStop),
@@ -1085,13 +1085,15 @@ MenuTable::BaseItemPtr TransportMenu( AudacityProject &project )
             AudioIONotBusyFlag | CanStopAudioStreamFlag, checkOff )
 #endif
       )
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraTransportMenu( AudacityProject & )
 {
    using namespace MenuTable;
-   return Menu( XO("T&ransport"),
+
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("T&ransport"),
       // PlayStop is already in the menus.
       /* i18n-hint: (verb) Start playing audio*/
       Command( wxT("Play"), XXO("Pl&ay"), FN(OnPlayStop),
@@ -1133,13 +1135,15 @@ MenuTable::BaseItemPtr ExtraTransportMenu( AudacityProject & )
       Command(wxT("KeyboardScrubForwards"), XXO("Scrub For&wards"),
          FN(OnKeyboardScrubForwards),
          CaptureNotBusyFlag | CanStopAudioStreamFlag, wxT("I\twantKeyup"))
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraPlayAtSpeedMenu( AudacityProject & )
 {
    using namespace MenuTable;
-   return Menu( XO("&Play-at-Speed"),
+
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&Play-at-Speed"),
       /* i18n-hint: 'Normal Play-at-Speed' doesn't loop or cut preview. */
       Command( wxT("PlayAtSpeed"), XXO("Normal Pl&ay-at-Speed"),
          FN(OnPlayAtSpeed), CaptureNotBusyFlag ),
@@ -1163,7 +1167,7 @@ MenuTable::BaseItemPtr ExtraPlayAtSpeedMenu( AudacityProject & )
       Command( wxT("MoveToNextLabel"), XXO("Move to &Next Label"),
          FN(OnMoveToNextLabel),
          CaptureNotBusyFlag | TrackPanelHasFocus, wxT("Alt+Right") )
-   );
+   ) );
 }
 
 #undef FN

src/menus/ViewMenus.cpp

@@ -430,8 +430,7 @@ static CommandHandlerObject &findCommandHandler(AudacityProject &project) {
 
 // Menu definitions
 
-#define FN(X) findCommandHandler, \
+#define FN(X) (& ViewActions::Handler :: X)
-   static_cast<CommandFunctorPointer>(& ViewActions::Handler :: X)
 
 MenuTable::BaseItemPtr ToolbarsMenu( AudacityProject& );
 
@@ -442,7 +441,8 @@ MenuTable::BaseItemPtr ViewMenu( AudacityProject& )
 
    static const auto checkOff = Options{}.CheckState( false );
 
-   return Menu( XO("&View"),
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&View"),
       Menu( XO("&Zoom"),
          Command( wxT("ZoomIn"), XXO("Zoom &In"), FN(OnZoomIn),
             ZoomInAvailableFlag, wxT("Ctrl+1") ),
@@ -547,7 +547,7 @@ MenuTable::BaseItemPtr ViewMenu( AudacityProject& )
       Command( wxT("ShowEffectsRack"), XXO("Show Effects Rack"),
          FN(OnShowEffectsRack), AlwaysEnabledFlag, checkOff )
 #endif
-   );
+   ) );
 }
 
 #undef FN

src/menus/WindowMenus.cpp

@@ -116,8 +116,7 @@ static CommandHandlerObject &findCommandHandler(AudacityProject &) {
 
 // Menu definitions
 
-#define FN(X) findCommandHandler, \
+#define FN(X) (& WindowActions::Handler :: X)
-   static_cast<CommandFunctorPointer>(& WindowActions::Handler :: X)
 
 MenuTable::BaseItemPtr WindowMenu( AudacityProject & )
 {
@@ -125,7 +124,9 @@ MenuTable::BaseItemPtr WindowMenu( AudacityProject & )
       // poor imitation of the Mac Windows Menu
       //////////////////////////////////////////////////////////////////////////
    using namespace MenuTable;
-   return Menu( XO("&Window"),
+
+   return FinderScope( findCommandHandler ).Eval(
+   Menu( XO("&Window"),
       /* i18n-hint: Standard Macintosh Window menu item:  Make (the current
        * window) shrink to an icon on the dock */
       Command( wxT("MacMinimize"), XXO("&Minimize"), FN(OnMacMinimize),
@@ -141,20 +142,21 @@ MenuTable::BaseItemPtr WindowMenu( AudacityProject & )
        * windows un-hidden */
       Command( wxT("MacBringAllToFront"), XXO("&Bring All to Front"),
          FN(OnMacBringAllToFront), AlwaysEnabledFlag )
-   );
+   ) );
 }
 
 MenuTable::BaseItemPtr ExtraWindowItems( AudacityProject & )
 {
    using namespace MenuTable;
 
-   return Items(
+   return FinderScope( findCommandHandler ).Eval(
+   Items(
       /* i18n-hint: Shrink all project windows to icons on the Macintosh
          tooldock */
       Command( wxT("MacMinimizeAll"), XXO("Minimize All Projects"),
          FN(OnMacMinimizeAll),
          AlwaysEnabledFlag, wxT("Ctrl+Alt+M") )
-   );
+   ) );
 }
 
 #undef FN

src/tracks/ui/Scrubbing.cpp

@@ -1121,18 +1121,18 @@ bool Scrubber::CanScrub() const
       HasWaveDataPred( *mProject );
 }
 
-// To supply the "finder" argument
-static CommandHandlerObject &findme(AudacityProject &project)
-{ return Scrubber::Get( project ); }
-
 MenuTable::BaseItemPtr Scrubber::Menu()
 {
    using Options = CommandManager::Options;
 
+   auto scope = MenuTable::FinderScope(
+      [](AudacityProject &project) -> CommandHandlerObject&
+         { return Scrubber::Get( project ); } );
+
    MenuTable::BaseItemPtrs ptrs;
    for (const auto &item : menuItems) {
       ptrs.push_back( MenuTable::Command( item.name, item.label,
-          findme, static_cast<CommandFunctorPointer>(item.memFn),
+          item.memFn,
           item.flags,
           item.StatusTest
              ? // a checkmark item