Manage Commands and CommandOutputTarget objects with smart pointers

src/Project.cpp

@@ -4632,13 +4632,13 @@ void AudacityProject::TP_DisplayStatusMessage(const wxString &msg)
 // (more overhead, but can be used from a non-GUI thread)
 void AudacityProject::SafeDisplayStatusMessage(const wxChar *msg)
 {
-   CommandOutputTarget *target
-      = new CommandOutputTarget(TargetFactory::ProgressDefault(),
+   auto target
+      = std::make_unique<CommandOutputTarget>(TargetFactory::ProgressDefault(),
                                 new StatusBarTarget(*mStatusBar),
                                 TargetFactory::MessageDefault());
    CommandType *type = CommandDirectory::Get()->LookUp(wxT("Message"));
    wxASSERT_MSG(type != NULL, wxT("Message command not found!"));
-   Command *statusCmd = type->Create(target);
+   CommandHolder statusCmd = type->Create(std::move(target));
    statusCmd->SetParameter(wxT("MessageString"), msg);
    ScriptCommandRelay::PostCommand(this, statusCmd);
 

src/Screenshot.cpp

@@ -97,7 +97,7 @@ class ScreenFrame final : public wxFrame
    void OnCaptureFirstTrack(wxCommandEvent & event);
    void OnCaptureSecondTrack(wxCommandEvent & event);
 
-   ScreenshotCommand *CreateCommand();
+   std::unique_ptr<ScreenshotCommand> CreateCommand();
 
    wxCheckBox *mDelayCheckBox;
    wxTextCtrl *mDirectoryTextBox;
@@ -105,7 +105,7 @@ class ScreenFrame final : public wxFrame
    wxToggleButton *mWhite;
    wxStatusBar *mStatus;
 
-   ScreenshotCommand *mCommand;
+   std::unique_ptr<ScreenshotCommand> mCommand;
    CommandExecutionContext mContext;
 
    DECLARE_EVENT_TABLE()
@@ -253,16 +253,16 @@ BEGIN_EVENT_TABLE(ScreenFrame, wxFrame)
 END_EVENT_TABLE();
 
 // Must not be called before CreateStatusBar!
-ScreenshotCommand *ScreenFrame::CreateCommand()
+std::unique_ptr<ScreenshotCommand> ScreenFrame::CreateCommand()
 {
    wxASSERT(mStatus != NULL);
-   CommandOutputTarget *output =
-      new CommandOutputTarget(new NullProgressTarget(),
+   auto output =
+      std::make_unique<CommandOutputTarget>(new NullProgressTarget(),
                               new StatusBarTarget(*mStatus),
                               new MessageBoxTarget());
    CommandType *type = CommandDirectory::Get()->LookUp(wxT("Screenshot"));
    wxASSERT_MSG(type != NULL, wxT("Screenshot command doesn't exist!"));
-   return new ScreenshotCommand(*type, output, this);
+   return std::make_unique<ScreenshotCommand>(*type, std::move(output), this);
 }
 
 ScreenFrame::ScreenFrame(wxWindow * parent, wxWindowID id)
@@ -293,7 +293,6 @@ ScreenFrame::ScreenFrame(wxWindow * parent, wxWindowID id)
 
 ScreenFrame::~ScreenFrame()
 {
-   delete mCommand;
 }
 
 void ScreenFrame::Populate()

src/commands/AppCommandEvent.cpp

@@ -28,13 +28,14 @@ DEFINE_EVENT_TYPE(wxEVT_APP_COMMAND_RECEIVED)
 IMPLEMENT_DYNAMIC_CLASS(AppCommandEvent, wxEvent)
 
 AppCommandEvent::AppCommandEvent(wxEventType commandType, int id)
-: wxCommandEvent(commandType, id), mCommand(NULL)
+: wxCommandEvent(commandType, id)
 { }
 
 // Copy constructor
-AppCommandEvent::AppCommandEvent(const AppCommandEvent &event) : wxCommandEvent(event)
+AppCommandEvent::AppCommandEvent(const AppCommandEvent &event)
+   : wxCommandEvent(event)
+   , mCommand(event.mCommand)
 {
-   this->mCommand = event.mCommand;
 }
 
 AppCommandEvent::~AppCommandEvent()
@@ -48,17 +49,13 @@ wxEvent *AppCommandEvent::Clone() const
 }
 
 /// Store a pointer to a command object
-void AppCommandEvent::SetCommand(Command *cmd)
+void AppCommandEvent::SetCommand(const CommandHolder &cmd)
 {
-   wxASSERT(NULL == mCommand);
+   wxASSERT(!mCommand);
    mCommand = cmd;
 }
 
-// When the command pointer is retrieved, the caller is responsible for
-// deletion.
-Command *AppCommandEvent::GetCommand()
+CommandHolder AppCommandEvent::GetCommand()
 {
-   Command *tmp = mCommand;
-   mCommand     = NULL;
-   return tmp;
+   return mCommand;
 }

src/commands/AppCommandEvent.h

@@ -18,15 +18,17 @@
 
 #include <wx/event.h>
 #include "../Audacity.h"
+#include "../MemoryX.h"
 
 DECLARE_EXPORTED_EVENT_TYPE(AUDACITY_DLL_API, wxEVT_APP_COMMAND_RECEIVED, -1);
 
 class Command;
+using CommandHolder = std::shared_ptr<Command>;
 
 class AppCommandEvent final : public wxCommandEvent
 {
 private:
-   Command *mCommand;
+   CommandHolder mCommand;
 
 public:
    AppCommandEvent(wxEventType commandType = wxEVT_APP_COMMAND_RECEIVED, int id = 0);
@@ -35,8 +37,8 @@ public:
    ~AppCommandEvent();
 
    wxEvent *Clone() const override;
-   void SetCommand(Command *cmd);
-   Command *GetCommand();
+   void SetCommand(const CommandHolder &cmd);
+   CommandHolder GetCommand();
 
 private:
    DECLARE_DYNAMIC_CLASS(AppCommandEvent)

src/commands/BatchEvalCommand.cpp

@@ -30,9 +30,9 @@ void BatchEvalCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("ChainName"), wxT(""), chainValidator);
 }
 
-Command *BatchEvalCommandType::Create(CommandOutputTarget *target)
+CommandHolder BatchEvalCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new BatchEvalCommand(*this, target);
+   return std::make_shared<BatchEvalCommand>(*this, std::move(target));
 }
 
 bool BatchEvalCommand::Apply(CommandExecutionContext WXUNUSED(context))

src/commands/BatchEvalCommand.h

@@ -31,15 +31,15 @@ class BatchEvalCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class BatchEvalCommand final : public CommandImplementation
 {
 public:
    BatchEvalCommand(CommandType &type,
-                    CommandOutputTarget *target)
-      : CommandImplementation(type, target)
+                    std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target))
    { }
 
    virtual ~BatchEvalCommand();

src/commands/Command.cpp

@@ -51,7 +51,6 @@ void DecoratedCommand::Error(const wxString &message)
 
 DecoratedCommand::~DecoratedCommand()
 {
-   delete mCommand;
 }
 
 wxString DecoratedCommand::GetName()
@@ -80,7 +79,8 @@ bool ApplyAndSendResponse::Apply(CommandExecutionContext context)
    if (result)
    {
       response += wxT("OK");
-   } else
+   }
+   else
    {
       response += wxT("Failed!");
    }
@@ -89,17 +89,16 @@ bool ApplyAndSendResponse::Apply(CommandExecutionContext context)
 }
 
 CommandImplementation::CommandImplementation(CommandType &type,
-      CommandOutputTarget *output)
+      std::unique_ptr<CommandOutputTarget> &&output)
 : mType(type),
    mParams(type.GetSignature().GetDefaults()),
-   mOutput(output)
+   mOutput(std::move(output))
 {
-   wxASSERT(output != NULL);
+   wxASSERT(mOutput);
 }
 
 CommandImplementation::~CommandImplementation()
 {
-   delete mOutput;
 }
 
 void CommandImplementation::TypeCheck(const wxString &typeName,

src/commands/Command.h

@@ -70,17 +70,19 @@ public:
    virtual bool Apply(CommandExecutionContext context) = 0;
 };
 
+using CommandHolder = std::shared_ptr<Command>;
+
 // Command which wraps another command
 class DecoratedCommand /* not final */ : public Command
 {
 protected:
-   Command *mCommand;
+   CommandHolder mCommand;
 public:
    void Progress(double completed) override;
    void Status(const wxString &message) override;
    void Error(const wxString &message) override;
 
-   DecoratedCommand(Command *cmd)
+   DecoratedCommand(const CommandHolder &cmd)
       : mCommand(cmd)
    {
       wxASSERT(cmd != NULL);
@@ -96,7 +98,7 @@ public:
 class ApplyAndSendResponse final : public DecoratedCommand
 {
 public:
-   ApplyAndSendResponse(Command *cmd)
+   ApplyAndSendResponse(const CommandHolder &cmd)
       : DecoratedCommand(cmd)
    { }
 
@@ -114,7 +116,7 @@ private:
    bool Valid(const wxString &paramName, const wxVariant &paramValue);
 
 protected:
-   CommandOutputTarget *mOutput;
+   std::unique_ptr<CommandOutputTarget> mOutput;
 
    // Convenience methods for allowing subclasses to access parameters
    void TypeCheck(const wxString &typeName,
@@ -135,7 +137,7 @@ public:
    /// Constructor should not be called directly; only by a factory which
    /// ensures name and params are set appropriately for the command.
    CommandImplementation(CommandType &type,
-                         CommandOutputTarget *output);
+                         std::unique_ptr<CommandOutputTarget> &&output);
 
    virtual ~CommandImplementation();
 

src/commands/CommandBuilder.cpp

@@ -30,20 +30,19 @@ system by constructing BatchCommandEval objects.
 #include "ScriptCommandRelay.h"
 
 CommandBuilder::CommandBuilder(const wxString &cmdString)
-   : mValid(false), mCommand(NULL)
+   : mValid(false)
 {
    BuildCommand(cmdString);
 }
 
 CommandBuilder::CommandBuilder(const wxString &cmdName, const wxString &params)
-   : mValid(false), mCommand(NULL)
+   : mValid(false)
 {
    BuildCommand(cmdName, params);
 }
 
 CommandBuilder::~CommandBuilder()
 {
-   Cleanup();
 }
 
 bool CommandBuilder::WasValid()
@@ -56,22 +55,13 @@ const wxString &CommandBuilder::GetErrorMessage()
    return mError;
 }
 
-Command *CommandBuilder::GetCommand()
+CommandHolder CommandBuilder::GetCommand()
 {
    wxASSERT(mValid);
-   wxASSERT(NULL != mCommand);
-   Command *tmp = mCommand;
-   mCommand = NULL;
-   return tmp;
-}
-
-void CommandBuilder::Cleanup()
-{
-   if (mCommand != NULL)
-   {
-      delete mCommand;
-      mCommand = NULL;
-   }
+   wxASSERT(mCommand);
+   auto result = mCommand;
+   mCommand.reset();
+   return result;
 }
 
 void CommandBuilder::Failure(const wxString &msg)
@@ -80,7 +70,7 @@ void CommandBuilder::Failure(const wxString &msg)
    mValid = false;
 }
 
-void CommandBuilder::Success(Command *cmd)
+void CommandBuilder::Success(const CommandHolder &cmd)
 {
    mCommand = cmd;
    mValid = true;
@@ -92,8 +82,8 @@ void CommandBuilder::BuildCommand(const wxString &cmdName,
    // Stage 1: create a Command object of the right type
 
    CommandMessageTarget *scriptOutput = ScriptCommandRelay::GetResponseTarget();
-   CommandOutputTarget *output
-      = new CommandOutputTarget(new NullProgressTarget(),
+   auto output
+      = std::make_unique<CommandOutputTarget>(new NullProgressTarget(),
                                 scriptOutput,
                                 scriptOutput);
 
@@ -104,15 +94,15 @@ void CommandBuilder::BuildCommand(const wxString &cmdName,
       // Fall back to hoping the Batch Command system can handle it
       CommandType *type = CommandDirectory::Get()->LookUp(wxT("BatchCommand"));
       wxASSERT(type != NULL);
-      mCommand = type->Create(output);
+      mCommand = type->Create(std::move(output));
       mCommand->SetParameter(wxT("CommandName"), cmdName);
       mCommand->SetParameter(wxT("ParamString"), cmdParamsArg);
-      Success(new ApplyAndSendResponse(mCommand));
+      Success(std::make_shared<ApplyAndSendResponse>(mCommand));
       return;
    }
 
    CommandSignature &signature = factory->GetSignature();
-   mCommand = factory->Create(output);
+   mCommand = factory->Create(std::move(output));
 
    // Stage 2: set the parameters
 
@@ -165,7 +155,7 @@ void CommandBuilder::BuildCommand(const wxString &cmdName,
       cmdParams = cmdParams.Mid(splitAt);
    }
 
-   Success(new ApplyAndSendResponse(mCommand));
+   Success(std::make_shared<ApplyAndSendResponse>(mCommand));
 }
 
 void CommandBuilder::BuildCommand(const wxString &cmdStringArg)

src/commands/CommandBuilder.h

@@ -17,6 +17,7 @@
 #define __COMMANDBUILDER__
 
 class Command;
+using CommandHolder = std::shared_ptr<Command>;
 class wxString;
 
 // CommandBuilder has the task of validating and interpreting a command string.
@@ -26,11 +27,11 @@ class CommandBuilder
 {
    private:
       bool mValid;
-      Command *mCommand;
+      CommandHolder mCommand;
       wxString mError;
 
       void Failure(const wxString &msg = wxEmptyString);
-      void Success(Command *cmd);
+      void Success(const CommandHolder &cmd);
       void BuildCommand(const wxString &cmdName, const wxString &cmdParams);
       void BuildCommand(const wxString &cmdString);
    public:
@@ -39,8 +40,7 @@ class CommandBuilder
                      const wxString &cmdParams);
       ~CommandBuilder();
       bool WasValid();
-      Command *GetCommand();
-      void Cleanup();
+      CommandHolder GetCommand();
       const wxString &GetErrorMessage();
 };
 #endif /* End of include guard: __COMMANDBUILDER__ */

src/commands/CommandHandler.cpp

@@ -41,7 +41,7 @@ void CommandHandler::SetProject(AudacityProject *)
 void CommandHandler::OnReceiveCommand(AppCommandEvent &event)
 {
    // First retrieve the actual command from the event 'envelope'.
-   Command *cmd = event.GetCommand();
+   CommandHolder cmd = event.GetCommand();
 
    // JKC: In case the user changed the project, let us track that.
    // This saves us the embarrassment (crash) of a NEW project
@@ -53,9 +53,6 @@ void CommandHandler::OnReceiveCommand(AppCommandEvent &event)
    // different project.
    cmd->Apply(*mCurrentContext);
 
-   // Done with the command so DELETE it.
-   delete cmd;
-
    // Redraw the project
    mCurrentContext->GetProject()->RedrawProject();
 }

src/commands/CommandType.h

@@ -17,8 +17,10 @@
 #define __COMMANDTYPE__
 
 #include "CommandMisc.h"
+#include "../MemoryX.h"
 
 class Command;
+using CommandHolder = std::shared_ptr<Command>;
 class CommandOutputTarget;
 class CommandSignature;
 class wxString;
@@ -47,7 +49,7 @@ public:
    virtual void BuildSignature(CommandSignature &signature) = 0;
 
    // Create a command instance with the specified output target
-   virtual Command *Create(CommandOutputTarget *target) = 0;
+   virtual CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) = 0;
 };
 
 #endif /* End of include guard: __COMMANDTYPE__ */

src/commands/CompareAudioCommand.cpp

@@ -33,9 +33,9 @@ void CompareAudioCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("Threshold"), 0.0, thresholdValidator);
 }
 
-Command *CompareAudioCommandType::Create(CommandOutputTarget *target)
+CommandHolder CompareAudioCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new CompareAudioCommand(*this, target);
+   return std::make_shared<CompareAudioCommand>(*this, std::move(target));
 }
 
 // Update member variables with project selection data (and validate)

src/commands/CompareAudioCommand.h

@@ -27,7 +27,7 @@ class CompareAudioCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class CompareAudioCommand final : public CommandImplementation
@@ -44,8 +44,8 @@ protected:
    double CompareSample(double value1, double value2) /* not override */;
 
 public:
-   CompareAudioCommand(CommandType &type, CommandOutputTarget *target)
-      : CommandImplementation(type, target)
+   CompareAudioCommand(CommandType &type, std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target))
    { }
    bool Apply(CommandExecutionContext context) override;
 };

src/commands/ExecMenuCommand.cpp

@@ -28,9 +28,9 @@ void ExecMenuCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("CommandName"), wxT(""), menuCommandValidator);
 }
 
-Command *ExecMenuCommandType::Create(CommandOutputTarget *target)
+CommandHolder ExecMenuCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new ExecMenuCommand(*this, target);
+   return std::make_shared<ExecMenuCommand>(*this, std::move(target));
 }
 
 bool ExecMenuCommand::Apply(CommandExecutionContext context)

src/commands/ExecMenuCommand.h

@@ -28,15 +28,15 @@ class ExecMenuCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class ExecMenuCommand final : public CommandImplementation
 {
 public:
    ExecMenuCommand(CommandType &type,
-                   CommandOutputTarget *target)
-      : CommandImplementation(type, target)
+                   std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target))
    { }
    virtual ~ExecMenuCommand() { }
    bool Apply(CommandExecutionContext context) override;

src/commands/GetAllMenuCommands.cpp

@@ -28,9 +28,9 @@ void GetAllMenuCommandsType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("ShowStatus"), 0, showStatusValidator);
 }
 
-Command *GetAllMenuCommandsType::Create(CommandOutputTarget *target)
+CommandHolder GetAllMenuCommandsType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new GetAllMenuCommands(*this, target);
+   return std::make_shared<GetAllMenuCommands>(*this, std::move(target));
 }
 
 bool GetAllMenuCommands::Apply(CommandExecutionContext context)

src/commands/GetAllMenuCommands.h

@@ -28,15 +28,15 @@ class GetAllMenuCommandsType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class GetAllMenuCommands final : public CommandImplementation
 {
 public:
    GetAllMenuCommands(CommandType &type,
-                      CommandOutputTarget *target)
-      : CommandImplementation(type, target)
+                      std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target))
    { }
 
    virtual ~GetAllMenuCommands()

src/commands/GetProjectInfoCommand.cpp

@@ -39,9 +39,9 @@ void GetProjectInfoCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("Type"), wxT("Name"), infoTypeValidator);
 }
 
-Command *GetProjectInfoCommandType::Create(CommandOutputTarget *target)
+CommandHolder GetProjectInfoCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new GetProjectInfoCommand(*this, target);
+   return std::make_shared<GetProjectInfoCommand>(*this, std::move(target));
 }
 
 

src/commands/GetProjectInfoCommand.h

@@ -24,15 +24,15 @@ class GetProjectInfoCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 
 class GetProjectInfoCommand final : public CommandImplementation
 {
 public:
-   GetProjectInfoCommand(CommandType &type, CommandOutputTarget *target)
-      : CommandImplementation(type, target)
+   GetProjectInfoCommand(CommandType &type, std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target))
    { }
    virtual ~GetProjectInfoCommand()
    { }

src/commands/GetTrackInfoCommand.cpp

@@ -46,9 +46,9 @@ void GetTrackInfoCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("Type"), wxT("Name"), infoTypeValidator);
 }
 
-Command *GetTrackInfoCommandType::Create(CommandOutputTarget *target)
+CommandHolder GetTrackInfoCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new GetTrackInfoCommand(*this, target);
+   return std::make_shared<GetTrackInfoCommand>(*this, std::move(target));
 }
 
 

src/commands/GetTrackInfoCommand.h

@@ -24,14 +24,14 @@ class GetTrackInfoCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class GetTrackInfoCommand final : public CommandImplementation
 {
 public:
-   GetTrackInfoCommand(CommandType &type, CommandOutputTarget *target)
-      : CommandImplementation(type, target)
+   GetTrackInfoCommand(CommandType &type, std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target))
    { }
    virtual ~GetTrackInfoCommand()
    { }

src/commands/HelpCommand.cpp

@@ -28,9 +28,9 @@ void HelpCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("CommandName"), wxT(""), commandNameValidator);
 }
 
-Command *HelpCommandType::Create(CommandOutputTarget *target)
+CommandHolder HelpCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new HelpCommand(*this, target);
+   return std::make_shared<HelpCommand>(*this, std::move(target));
 }
 
 bool HelpCommand::Apply(CommandExecutionContext WXUNUSED(context))

src/commands/HelpCommand.h

@@ -27,14 +27,14 @@ class HelpCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class HelpCommand final : public CommandImplementation
 {
 public:
-   HelpCommand(HelpCommandType &type, CommandOutputTarget *target)
-      : CommandImplementation(type, target) { }
+   HelpCommand(HelpCommandType &type, std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target)) { }
    bool Apply(CommandExecutionContext context) override;
 };
 

src/commands/ImportExportCommands.cpp

@@ -31,9 +31,9 @@ void ImportCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("Filename"), wxT(""), filenameValidator);
 }
 
-Command *ImportCommandType::Create(CommandOutputTarget *target)
+CommandHolder ImportCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new ImportCommand(*this, target);
+   return std::make_shared<ImportCommand>(*this, std::move(target));
 }
 
 bool ImportCommand::Apply(CommandExecutionContext context)
@@ -66,9 +66,9 @@ void ExportCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("Channels"), 1, channelsValidator);
 }
 
-Command *ExportCommandType::Create(CommandOutputTarget *target)
+CommandHolder ExportCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new ExportCommand(*this, target);
+   return std::make_shared<ExportCommand>(*this, std::move(target));
 }
 
 bool ExportCommand::Apply(CommandExecutionContext context)

src/commands/ImportExportCommands.h

@@ -27,15 +27,15 @@ class ImportCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class ImportCommand final : public CommandImplementation
 {
 public:
    ImportCommand(CommandType &type,
-                    CommandOutputTarget *target)
-      : CommandImplementation(type, target)
+                    std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target))
    { }
 
    virtual ~ImportCommand();
@@ -49,15 +49,15 @@ class ExportCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class ExportCommand final : public CommandImplementation
 {
 public:
    ExportCommand(CommandType &type,
-                    CommandOutputTarget *target)
-      : CommandImplementation(type, target)
+                    std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target))
    { }
 
    virtual ~ExportCommand();

src/commands/MessageCommand.cpp

@@ -27,9 +27,9 @@ void MessageCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("MessageString"), wxT(""), stringValidator);
 }
 
-Command *MessageCommandType::Create(CommandOutputTarget *target)
+CommandHolder MessageCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new MessageCommand(*this, target);
+   return std::make_shared<MessageCommand>(*this, std::move(target));
 }
 
 bool MessageCommand::Apply(CommandExecutionContext WXUNUSED(context))

src/commands/MessageCommand.h

@@ -29,15 +29,15 @@ class MessageCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class MessageCommand final : public CommandImplementation
 {
 public:
    MessageCommand(CommandType &type,
-                  CommandOutputTarget *target)
-      : CommandImplementation(type, target) {}
+                  std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target)) {}
    bool Apply(CommandExecutionContext context) override;
 };
 

src/commands/OpenSaveCommands.cpp

@@ -32,9 +32,9 @@ void OpenProjectCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("Filename"), wxT(""), filenameValidator);
 }
 
-Command *OpenProjectCommandType::Create(CommandOutputTarget *target)
+CommandHolder OpenProjectCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new OpenProjectCommand(*this, target);
+   return std::make_shared<OpenProjectCommand>(*this, std::move(target));
 }
 
 bool OpenProjectCommand::Apply(CommandExecutionContext context)
@@ -80,9 +80,9 @@ void SaveProjectCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("Filename"), wxT(""), filenameValidator);
 }
 
-Command *SaveProjectCommandType::Create(CommandOutputTarget *target)
+CommandHolder SaveProjectCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new SaveProjectCommand(*this, target);
+   return std::make_shared<SaveProjectCommand>(*this, std::move(target));
 }
 
 bool SaveProjectCommand::Apply(CommandExecutionContext context)

src/commands/OpenSaveCommands.h

@@ -27,15 +27,15 @@ class OpenProjectCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class OpenProjectCommand final : public CommandImplementation
 {
 public:
    OpenProjectCommand(CommandType &type,
-                    CommandOutputTarget *target)
-      : CommandImplementation(type, target)
+                    std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target))
    { }
 
    virtual ~OpenProjectCommand();
@@ -49,15 +49,15 @@ class SaveProjectCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class SaveProjectCommand final : public CommandImplementation
 {
 public:
    SaveProjectCommand(CommandType &type,
-                    CommandOutputTarget *target)
-      : CommandImplementation(type, target)
+                    std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target))
    { }
 
    virtual ~SaveProjectCommand();

src/commands/PreferenceCommands.cpp

@@ -30,9 +30,9 @@ void GetPreferenceCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("PrefName"), wxT(""), prefNameValidator);
 }
 
-Command *GetPreferenceCommandType::Create(CommandOutputTarget *target)
+CommandHolder GetPreferenceCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new GetPreferenceCommand(*this, target);
+   return std::make_shared<GetPreferenceCommand>(*this, std::move(target));
 }
 
 bool GetPreferenceCommand::Apply(CommandExecutionContext WXUNUSED(context))
@@ -65,9 +65,9 @@ void SetPreferenceCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("PrefValue"), wxT(""), prefValueValidator);
 }
 
-Command *SetPreferenceCommandType::Create(CommandOutputTarget *target)
+CommandHolder SetPreferenceCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new SetPreferenceCommand(*this, target);
+   return std::make_shared<SetPreferenceCommand>(*this, std::move(target));
 }
 
 bool SetPreferenceCommand::Apply(CommandExecutionContext WXUNUSED(context))

src/commands/PreferenceCommands.h

@@ -30,15 +30,15 @@ class GetPreferenceCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class GetPreferenceCommand final : public CommandImplementation
 {
 public:
    GetPreferenceCommand(CommandType &type,
-                    CommandOutputTarget *target)
-      : CommandImplementation(type, target)
+                    std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target))
    { }
 
    virtual ~GetPreferenceCommand();
@@ -52,15 +52,15 @@ class SetPreferenceCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class SetPreferenceCommand final : public CommandImplementation
 {
 public:
    SetPreferenceCommand(CommandType &type,
-                    CommandOutputTarget *target)
-      : CommandImplementation(type, target)
+                    std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target))
    { }
 
    virtual ~SetPreferenceCommand();

src/commands/ScreenshotCommand.cpp

@@ -306,9 +306,9 @@ void ScreenshotCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("FilePath"), wxT(""), filePathValidator);
 }
 
-Command *ScreenshotCommandType::Create(CommandOutputTarget *target)
+CommandHolder ScreenshotCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new ScreenshotCommand(*this, target);
+   return std::make_shared<ScreenshotCommand>(*this, std::move(target));
 }
 
 wxString ScreenshotCommand::MakeFileName(const wxString &path, const wxString &basename)

src/commands/ScreenshotCommand.h

@@ -28,7 +28,7 @@ class ScreenshotCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class ScreenshotCommand final : public CommandImplementation
@@ -53,9 +53,9 @@ private:
 public:
    wxTopLevelWindow *GetFrontWindow(AudacityProject *project);
    ScreenshotCommand(CommandType &type,
-                     CommandOutputTarget *output,
+                     std::unique_ptr<CommandOutputTarget> &&output,
                      wxWindow *ignore = NULL)
-      : CommandImplementation(type, output),
+      : CommandImplementation(type, std::move(output)),
         mIgnore(ignore),
         mBackground(false)
    { }

src/commands/ScriptCommandRelay.cpp

@@ -51,7 +51,7 @@ void ScriptCommandRelay::Run()
 }
 
 /// Send a command to a project, to be applied in that context.
-void ScriptCommandRelay::PostCommand(AudacityProject *project, Command *cmd)
+void ScriptCommandRelay::PostCommand(AudacityProject *project, const CommandHolder &cmd)
 {
    wxASSERT(project != NULL);
    wxASSERT(cmd != NULL);
@@ -66,20 +66,22 @@ void ScriptCommandRelay::PostCommand(AudacityProject *project, Command *cmd)
 /// the GUI at a time causes problems with wxwidgets.
 int ExecCommand(wxString *pIn, wxString *pOut)
 {
-   CommandBuilder builder(*pIn);
-   if (builder.WasValid())
    {
-      AudacityProject *project = GetActiveProject();
-      project->SafeDisplayStatusMessage(wxT("Received script command"));
-      Command *cmd = builder.GetCommand();
-      ScriptCommandRelay::PostCommand(project, cmd);
+      CommandBuilder builder(*pIn);
+      if (builder.WasValid())
+      {
+         AudacityProject *project = GetActiveProject();
+         project->SafeDisplayStatusMessage(wxT("Received script command"));
+         CommandHolder cmd = builder.GetCommand();
+         ScriptCommandRelay::PostCommand(project, cmd);
 
-      *pOut = wxEmptyString;
-   } else
-   {
-      *pOut = wxT("Syntax error!\n");
-      *pOut += builder.GetErrorMessage() + wxT("\n");
-      builder.Cleanup();
+         *pOut = wxEmptyString;
+      }
+      else
+      {
+         *pOut = wxT("Syntax error!\n");
+         *pOut += builder.GetErrorMessage() + wxT("\n");
+      }
    }
 
    // Wait until all responses from the command have been received.

src/commands/ScriptCommandRelay.h

@@ -17,6 +17,7 @@
 #define __SCRIPTCOMMANDRELAY__
 
 #include "../Audacity.h"
+#include "../MemoryX.h"
 
 class CommandHandler;
 class ResponseQueue;
@@ -24,6 +25,7 @@ class Response;
 class ResponseQueueTarget;
 class AudacityProject;
 class Command;
+using CommandHolder = std::shared_ptr<Command>;
 class wxString;
 
 typedef int (*tpExecScriptServerFunc)( wxString * pIn, wxString * pOut);
@@ -47,7 +49,7 @@ class ScriptCommandRelay
       static void SetCommandHandler(CommandHandler &ch);
 
       static void Run();
-      static void PostCommand(AudacityProject *project, Command *cmd);
+      static void PostCommand(AudacityProject *project, const CommandHolder &cmd);
       static void SendResponse(const wxString &response);
       static Response ReceiveResponse();
       static ResponseQueueTarget *GetResponseTarget();

src/commands/SelectCommand.cpp

@@ -49,9 +49,9 @@ void SelectCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("TrackName"), 0, trackNameValidator);
 }
 
-Command *SelectCommandType::Create(CommandOutputTarget *target)
+CommandHolder SelectCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new SelectCommand(*this, target);
+   return std::make_shared<SelectCommand>(*this, std::move(target));
 }
 
 bool SelectCommand::Apply(CommandExecutionContext context)

src/commands/SelectCommand.h

@@ -24,14 +24,14 @@ class SelectCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class SelectCommand final : public CommandImplementation
 {
 public:
-   SelectCommand(SelectCommandType &type, CommandOutputTarget *target)
-      : CommandImplementation(type, target) { }
+   SelectCommand(SelectCommandType &type, std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target)) { }
    bool Apply(CommandExecutionContext context) override;
 };
 

src/commands/SetProjectInfoCommand.cpp

@@ -41,9 +41,9 @@ void SetProjectInfoCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT(kSetOfTracksStr), wxT("x"), TracksSetValidator);
 }
 
-Command *SetProjectInfoCommandType::Create(CommandOutputTarget *target)
+CommandHolder SetProjectInfoCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new SetProjectInfoCommand(*this, target);
+   return std::make_shared<SetProjectInfoCommand>(*this, std::move(target));
 }
 
 

src/commands/SetProjectInfoCommand.h

@@ -28,15 +28,15 @@ class SetProjectInfoCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 
 class SetProjectInfoCommand final : public CommandImplementation
 {
 public:
-   SetProjectInfoCommand(CommandType &type, CommandOutputTarget *target)
-      : CommandImplementation(type, target)
+   SetProjectInfoCommand(CommandType &type, std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target))
    { }
    virtual ~SetProjectInfoCommand()
    { }

src/commands/SetTrackInfoCommand.cpp

@@ -37,9 +37,9 @@ void SetTrackInfoCommandType::BuildSignature(CommandSignature &signature)
    signature.AddParameter(wxT("Name"), wxT("Unnamed"), nameValidator);
 }
 
-Command *SetTrackInfoCommandType::Create(CommandOutputTarget *target)
+CommandHolder SetTrackInfoCommandType::Create(std::unique_ptr<CommandOutputTarget> &&target)
 {
-   return new SetTrackInfoCommand(*this, target);
+   return std::make_shared<SetTrackInfoCommand>(*this, std::move(target));
 }
 
 bool SetTrackInfoCommand::Apply(CommandExecutionContext context)

src/commands/SetTrackInfoCommand.h

@@ -24,14 +24,14 @@ class SetTrackInfoCommandType final : public CommandType
 public:
    wxString BuildName() override;
    void BuildSignature(CommandSignature &signature) override;
-   Command *Create(CommandOutputTarget *target) override;
+   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
 };
 
 class SetTrackInfoCommand final : public CommandImplementation
 {
 public:
-   SetTrackInfoCommand(CommandType &type, CommandOutputTarget *target)
-      : CommandImplementation(type, target)
+   SetTrackInfoCommand(CommandType &type, std::unique_ptr<CommandOutputTarget> &&target)
+      : CommandImplementation(type, std::move(target))
    { }
    virtual ~SetTrackInfoCommand()
    { }