Eliminate some more news and deletes, with the help of class Maybe...

... which can stack-allocate an object conditionally.

(Name inspired by Haskell.)

src/Audacity.h

@@ -242,4 +242,118 @@ namespace std {
 }
 #endif
 
+/*
+* template class Maybe<X>
+* Can be used for monomorphic objects that are stack-allocable, but only conditionally constructed.
+* You might also use it as a member.
+* Initialize with create(), then use like a smart pointer,
+* with *, ->, get(), reset(), or in if()
+*/
+
+template<typename X>
+class Maybe {
+public:
+
+   // Construct as NULL
+   Maybe() {}
+
+   // Supply the copy and move, so you might use this as a class member too
+   Maybe(const Maybe &that)
+   {
+      if (that.get())
+         create(*that);
+   }
+
+   Maybe& operator= (const Maybe &that)
+   {
+      if (this != &that) {
+         if (that.get())
+            create(*that);
+         else
+            reset();
+      }
+      return *this;
+   }
+
+   Maybe(Maybe &&that)
+   {
+      if (that.get())
+         create(::std::move(*that));
+   }
+
+   Maybe& operator= (Maybe &&that)
+   {
+      if (this != &that) {
+         if (that.get())
+            create(::std::move(*that));
+         else
+            reset();
+      }
+      return *this;
+   }
+
+   // Make an object in the buffer, passing constructor arguments,
+   // but destroying any previous object first
+   // Note that if constructor throws, we remain in a consistent
+   // NULL state -- giving exception safety but only weakly
+   // (previous value was lost if present)
+   template<typename... Args>
+   void create(Args... args)
+   {
+      // Lose any old value
+      reset();
+      // Create new value
+      pp = safenew(address()) X( std::forward<Args>(args)... );
+   }
+
+   // Destroy any object that was built in it
+   ~Maybe()
+   {
+      reset();
+   }
+
+   // Pointer-like operators
+
+   // Dereference, with the usual bad consequences if NULL
+   X &operator* () const
+   {
+      return *pp;
+   }
+
+   X *operator-> () const
+   {
+      return pp;
+   }
+
+   X* get() const
+   {
+      return pp;
+   }
+
+   void reset()
+   {
+      if (pp)
+         pp->~X(), pp = nullptr;
+   }
+
+   // So you can say if(ptr)
+   explicit operator bool() const
+   {
+      return pp != nullptr;
+   }
+
+private:
+   X* address()
+   {
+      return reinterpret_cast<X*>(&storage);
+   }
+
+   // Data
+   typename ::std::aligned_storage<
+      sizeof(X)
+      // , alignof(X) // Not here yet in all compilers
+   >::type storage{};
+   X* pp{ nullptr };
+};
+
 #endif // __AUDACITY_H__

src/AudacityApp.cpp

@@ -317,7 +317,7 @@ void QuitAudacity(bool bForce)
    AudacityProject::DeleteAllProjectsDeleteLock();
 
    //remove our logger
-   delete wxLog::SetActiveTarget(NULL);
+   std::unique_ptr<wxLog>{ wxLog::SetActiveTarget(NULL) }; // DELETE
 
    if (bForce)
    {
@@ -1147,7 +1147,7 @@ bool AudacityApp::OnInit()
    // Ensure we have an event loop during initialization
    wxEventLoopGuarantor eventLoop;
 
-   delete wxLog::SetActiveTarget(new AudacityLogger);
+   std::unique_ptr < wxLog > { wxLog::SetActiveTarget(new AudacityLogger) }; // DELETE
 
    mLocale = NULL;
 

src/AudioIO.cpp

@@ -1343,72 +1343,67 @@ bool AudioIO::StartPortAudioStream(double sampleRate,
    mNumPlaybackChannels = numPlaybackChannels;
    mNumCaptureChannels = numCaptureChannels;
 
-   PaStreamParameters *playbackParameters = NULL;
+   bool usePlayback = false, useCapture = false;
-   PaStreamParameters *captureParameters = NULL;
+   PaStreamParameters playbackParameters{};
+   PaStreamParameters captureParameters{};
 
    double latencyDuration = DEFAULT_LATENCY_DURATION;
    gPrefs->Read(wxT("/AudioIO/LatencyDuration"), &latencyDuration);
 
    if( numPlaybackChannels > 0)
    {
-      playbackParameters = new PaStreamParameters;
+      usePlayback = true;
+
       // this sets the device index to whatever is "right" based on preferences,
       // then defaults
-      playbackParameters->device = getPlayDevIndex();
+      playbackParameters.device = getPlayDevIndex();
 
       const PaDeviceInfo *playbackDeviceInfo;
-      playbackDeviceInfo = Pa_GetDeviceInfo( playbackParameters->device );
+      playbackDeviceInfo = Pa_GetDeviceInfo( playbackParameters.device );
 
       if( playbackDeviceInfo == NULL )
-      {
-         delete playbackParameters;
          return false;
-      }
 
       // regardless of source formats, we always mix to float
-      playbackParameters->sampleFormat = paFloat32;
+      playbackParameters.sampleFormat = paFloat32;
-      playbackParameters->hostApiSpecificStreamInfo = NULL;
+      playbackParameters.hostApiSpecificStreamInfo = NULL;
-      playbackParameters->channelCount = mNumPlaybackChannels;
+      playbackParameters.channelCount = mNumPlaybackChannels;
 
       if (mSoftwarePlaythrough)
-         playbackParameters->suggestedLatency =
+         playbackParameters.suggestedLatency =
             playbackDeviceInfo->defaultLowOutputLatency;
       else
-         playbackParameters->suggestedLatency = latencyDuration/1000.0;
+         playbackParameters.suggestedLatency = latencyDuration/1000.0;
 
       mOutputMeter = mOwningProject->GetPlaybackMeter();
    }
 
    if( numCaptureChannels > 0)
    {
+      useCapture = true;
       mCaptureFormat = captureFormat;
 
-      captureParameters = new PaStreamParameters;
       const PaDeviceInfo *captureDeviceInfo;
       // retrieve the index of the device set in the prefs, or a sensible
       // default if it isn't set/valid
-      captureParameters->device = getRecordDevIndex();
+      captureParameters.device = getRecordDevIndex();
 
-      captureDeviceInfo = Pa_GetDeviceInfo( captureParameters->device );
+      captureDeviceInfo = Pa_GetDeviceInfo( captureParameters.device );
 
       if( captureDeviceInfo == NULL )
-      {
-         delete captureParameters;
-         delete playbackParameters;
          return false;
-      }
 
-      captureParameters->sampleFormat =
+      captureParameters.sampleFormat =
          AudacityToPortAudioSampleFormat(mCaptureFormat);
 
-      captureParameters->hostApiSpecificStreamInfo = NULL;
+      captureParameters.hostApiSpecificStreamInfo = NULL;
-      captureParameters->channelCount = mNumCaptureChannels;
+      captureParameters.channelCount = mNumCaptureChannels;
 
       if (mSoftwarePlaythrough)
-         captureParameters->suggestedLatency =
+         captureParameters.suggestedLatency =
             captureDeviceInfo->defaultHighInputLatency;
       else
-         captureParameters->suggestedLatency = latencyDuration/1000.0;
+         captureParameters.suggestedLatency = latencyDuration/1000.0;
 
       mInputMeter = mOwningProject->GetCaptureMeter();
    }
@@ -1429,7 +1424,8 @@ bool AudioIO::StartPortAudioStream(double sampleRate,
 #endif
 #endif
    mLastPaError = Pa_OpenStream( &mPortStreamV19,
-                                 captureParameters, playbackParameters,
+                                 useCapture ? &captureParameters : NULL,
+                                 usePlayback ? &playbackParameters : NULL,
                                  mRate, paFramesPerBufferUnspecified,
                                  paNoFlag,
                                  audacityAudioCallback, NULL );
@@ -1457,10 +1453,6 @@ bool AudioIO::StartPortAudioStream(double sampleRate,
    }
 #endif
 
-   // these may be null, but deleting a null pointer should never crash.
-   delete captureParameters;
-   delete playbackParameters;
-
    return (mLastPaError == paNoError);
 }
 

src/BlockFile.cpp

@@ -597,25 +597,27 @@ AliasBlockFile::~AliasBlockFile()
 bool AliasBlockFile::ReadSummary(void *data)
 {
    wxFFile summaryFile(mFileName.GetFullPath(), wxT("rb"));
-   wxLogNull *silence=0;
-   if(mSilentLog)silence= new wxLogNull();
 
-   if( !summaryFile.IsOpened() ){
+   {
+      Maybe<wxLogNull> silence{};
+      if (mSilentLog)
+         silence.create();
 
-      // NEW model; we need to return valid data
+      if (!summaryFile.IsOpened()){
-      memset(data,0,(size_t)mSummaryInfo.totalSummaryBytes);
-      if(silence) delete silence;
 
-      // we silence the logging for this operation in this object
+         // NEW model; we need to return valid data
-      // after first occurrence of error; it's already reported and
+         memset(data, 0, (size_t)mSummaryInfo.totalSummaryBytes);
-      // spewing at the user will complicate the user's ability to
-      // deal
-      mSilentLog=TRUE;
-      return true;
 
-   }else mSilentLog=FALSE; // worked properly, any future error is NEW
+         // we silence the logging for this operation in this object
+         // after first occurrence of error; it's already reported and
+         // spewing at the user will complicate the user's ability to
+         // deal
+         mSilentLog = TRUE;
+         return true;
 
-   if(silence) delete silence;
+      }
+      else mSilentLog = FALSE; // worked properly, any future error is NEW
+   }
 
    int read = summaryFile.Read(data, (size_t)mSummaryInfo.totalSummaryBytes);
 

src/DirManager.cpp

@@ -197,7 +197,6 @@ static int RecursivelyEnumerate(wxString dirPath,
    return count;
 }
 
-
 static int RecursivelyEnumerateWithProgress(wxString dirPath,
                                              wxArrayString& filePathArray, // output: all files in dirPath tree
                                              wxString dirspec,
@@ -205,19 +204,16 @@ static int RecursivelyEnumerateWithProgress(wxString dirPath,
                                              int progress_count,
                                              const wxChar* message)
 {
-   ProgressDialog *progress = NULL;
+   Maybe<ProgressDialog> progress{};
 
    if (message)
-      progress = new ProgressDialog(_("Progress"), message);
+      progress.create( _("Progress"), message );
 
    int count = RecursivelyEnumerate(
                   dirPath, filePathArray, dirspec,
                   bFiles, bDirs,
                   progress_count, 0,
-                  progress);
+                  progress.get());
-
-   if (progress)
-      delete progress;
 
    return count;
 }
@@ -291,10 +287,10 @@ static void RecursivelyRemove(wxArrayString& filePathArray, int count,
                               bool bFiles, bool bDirs,
                               const wxChar* message = NULL)
 {
-   ProgressDialog *progress = NULL;
+   Maybe<ProgressDialog> progress{};
 
    if (message)
-      progress = new ProgressDialog(_("Progress"), message);
+      progress.create( _("Progress"), message );
 
    for (int i = 0; i < count; i++) {
       const wxChar *file = filePathArray[i].c_str();
@@ -305,9 +301,6 @@ static void RecursivelyRemove(wxArrayString& filePathArray, int count,
       if (progress)
          progress->Update(i, count);
    }
-
-   if (progress)
-      delete progress;
 }
 
 

src/blockfile/LegacyBlockFile.cpp

@@ -69,26 +69,28 @@ void ComputeLegacySummaryInfo(wxFileName fileName,
    SampleBuffer data(info->frames64K * fields,
       info->format);
 
-   wxLogNull *silence=0;
-   wxFFile summaryFile(fileName.GetFullPath(), wxT("rb"));
    int read;
-   if(Silent)silence= new wxLogNull();
+   {
+      Maybe<wxLogNull> silence{};
+      wxFFile summaryFile(fileName.GetFullPath(), wxT("rb"));
+      if (Silent)
+         silence.create();
 
-   if( !summaryFile.IsOpened() ) {
+      if (!summaryFile.IsOpened()) {
-      wxLogWarning(wxT("Unable to access summary file %s; substituting silence for remainder of session"),
+         wxLogWarning(wxT("Unable to access summary file %s; substituting silence for remainder of session"),
-                   fileName.GetFullPath().c_str());
+            fileName.GetFullPath().c_str());
 
-      read=info->frames64K * info->bytesPerFrame;
+         read = info->frames64K * info->bytesPerFrame;
-      memset(data.ptr(), 0, read);
+         memset(data.ptr(), 0, read);
-   }else{
+      }
-      summaryFile.Seek(info->offset64K);
+      else{
-      read = summaryFile.Read(data.ptr(),
+         summaryFile.Seek(info->offset64K);
-                              info->frames64K *
+         read = summaryFile.Read(data.ptr(),
-                              info->bytesPerFrame);
+            info->frames64K *
+            info->bytesPerFrame);
+      }
    }
 
-   if(silence) delete silence;
-
    int count = read / info->bytesPerFrame;
 
    CopySamples(data.ptr(), info->format,
@@ -151,22 +153,23 @@ LegacyBlockFile::~LegacyBlockFile()
 bool LegacyBlockFile::ReadSummary(void *data)
 {
    wxFFile summaryFile(mFileName.GetFullPath(), wxT("rb"));
-   wxLogNull *silence=0;
+   int read;
-   if(mSilentLog)silence= new wxLogNull();
+   {
+      Maybe<wxLogNull> silence{};
+      if (mSilentLog)
+         silence.create();
 
-   if( !summaryFile.IsOpened() ){
+      if (!summaryFile.IsOpened()){
 
-      memset(data,0,(size_t)mSummaryInfo.totalSummaryBytes);
+         memset(data, 0, (size_t)mSummaryInfo.totalSummaryBytes);
 
-      if(silence) delete silence;
+         mSilentLog = TRUE;
-      mSilentLog=TRUE;
 
-      return true;
+         return true;
+      }
+
+      read = summaryFile.Read(data, (size_t)mSummaryInfo.totalSummaryBytes);
    }
-
-   int read = summaryFile.Read(data, (size_t)mSummaryInfo.totalSummaryBytes);
-
-   if(silence) delete silence;
    mSilentLog=FALSE;
 
    return (read == mSummaryInfo.totalSummaryBytes);
@@ -215,19 +218,20 @@ int LegacyBlockFile::ReadData(samplePtr data, sampleFormat format,
       sf = sf_open_fd(f.fd(), SFM_READ, &info, FALSE);
    }
 
-   wxLogNull *silence=0;
+   {
-   if(mSilentLog)silence= new wxLogNull();
+      Maybe<wxLogNull> silence{};
+      if (mSilentLog)
+         silence.create();
 
-   if (!sf){
+      if (!sf){
 
-      memset(data,0,SAMPLE_SIZE(format)*len);
+         memset(data, 0, SAMPLE_SIZE(format)*len);
 
-      if(silence) delete silence;
+         mSilentLog = TRUE;
-      mSilentLog=TRUE;
 
-      return len;
+         return len;
+      }
    }
-   if(silence) delete silence;
    mSilentLog=FALSE;
 
    sf_count_t seekstart = start +

src/blockfile/PCMAliasBlockFile.cpp

@@ -80,37 +80,37 @@ int PCMAliasBlockFile::ReadData(samplePtr data, sampleFormat format,
       return len;
    }
 
-   wxLogNull *silence=0;
-   if(mSilentAliasLog)silence= new wxLogNull();
-
-   memset(&info, 0, sizeof(info));
-
    wxFile f;   // will be closed when it goes out of scope
    SNDFILE *sf = NULL;
+   {
+      Maybe<wxLogNull> silence{};
+      if (mSilentAliasLog)
+         silence.create();
 
-   if (f.Exists(mAliasedFileName.GetFullPath())) { // Don't use Open if file does not exits
+      memset(&info, 0, sizeof(info));
-      if (f.Open(mAliasedFileName.GetFullPath())) {
+
-         // Even though there is an sf_open() that takes a filename, use the one that
+      if (f.Exists(mAliasedFileName.GetFullPath())) { // Don't use Open if file does not exits
-         // takes a file descriptor since wxWidgets can open a file with a Unicode name and
+         if (f.Open(mAliasedFileName.GetFullPath())) {
-         // libsndfile can't (under Windows).
+            // Even though there is an sf_open() that takes a filename, use the one that
-         ODManager::LockLibSndFileMutex();
+            // takes a file descriptor since wxWidgets can open a file with a Unicode name and
-         sf = sf_open_fd(f.fd(), SFM_READ, &info, FALSE);
+            // libsndfile can't (under Windows).
-         ODManager::UnlockLibSndFileMutex();
+            ODManager::LockLibSndFileMutex();
+            sf = sf_open_fd(f.fd(), SFM_READ, &info, FALSE);
+            ODManager::UnlockLibSndFileMutex();
+         }
+      }
+
+      if (!sf){
+         memset(data, 0, SAMPLE_SIZE(format)*len);
+         silence.reset();
+         mSilentAliasLog = TRUE;
+
+         // Set a marker to display an error message for the silence
+         if (!wxGetApp().ShouldShowMissingAliasedFileWarning())
+            wxGetApp().MarkAliasedFilesMissingWarning(this);
+         return len;
       }
    }
-
-   if (!sf){
-      memset(data,0,SAMPLE_SIZE(format)*len);
-      if(silence) delete silence;
-      mSilentAliasLog=TRUE;
-
-      // Set a marker to display an error message for the silence
-      if (!wxGetApp().ShouldShowMissingAliasedFileWarning())
-         wxGetApp().MarkAliasedFilesMissingWarning(this);
-      return len;
-   }
-
-   if(silence) delete silence;
    mSilentAliasLog=FALSE;
 
    ODManager::LockLibSndFileMutex();

src/blockfile/SimpleBlockFile.cpp

@@ -345,21 +345,21 @@ bool SimpleBlockFile::ReadSummary(void *data)
 
       wxFFile file(mFileName.GetFullPath(), wxT("rb"));
 
-      wxLogNull *silence=0;
+      {
-      if(mSilentLog)silence= new wxLogNull();
+         Maybe<wxLogNull> silence{};
+         if (mSilentLog)
+            silence.create();
 
-      if(!file.IsOpened() ){
+         if (!file.IsOpened()){
 
-         memset(data,0,(size_t)mSummaryInfo.totalSummaryBytes);
+            memset(data, 0, (size_t)mSummaryInfo.totalSummaryBytes);
 
-         if(silence) delete silence;
+            mSilentLog = TRUE;
-         mSilentLog=TRUE;
 
-         return true;
+            return true;
 
+         }
       }
-
-      if(silence) delete silence;
       mSilentLog=FALSE;
 
       // The offset is just past the au header
@@ -400,31 +400,31 @@ int SimpleBlockFile::ReadData(samplePtr data, sampleFormat format,
       //wxLogDebug("SimpleBlockFile::ReadData(): Reading data from disk.");
 
       SF_INFO info;
-      wxLogNull *silence=0;
-      if(mSilentLog)silence= new wxLogNull();
-
-      memset(&info, 0, sizeof(info));
-
       wxFile f;   // will be closed when it goes out of scope
       SNDFILE *sf = NULL;
+      {
+         Maybe<wxLogNull> silence{};
+         if (mSilentLog)
+            silence.create();
 
-      if (f.Open(mFileName.GetFullPath())) {
+         memset(&info, 0, sizeof(info));
-         // Even though there is an sf_open() that takes a filename, use the one that
+
-         // takes a file descriptor since wxWidgets can open a file with a Unicode name and
+         if (f.Open(mFileName.GetFullPath())) {
-         // libsndfile can't (under Windows).
+            // Even though there is an sf_open() that takes a filename, use the one that
-         sf = sf_open_fd(f.fd(), SFM_READ, &info, FALSE);
+            // takes a file descriptor since wxWidgets can open a file with a Unicode name and
+            // libsndfile can't (under Windows).
+            sf = sf_open_fd(f.fd(), SFM_READ, &info, FALSE);
+         }
+
+         if (!sf) {
+
+            memset(data, 0, SAMPLE_SIZE(format)*len);
+
+            mSilentLog = TRUE;
+
+            return len;
+         }
       }
-
-      if (!sf) {
-
-         memset(data,0,SAMPLE_SIZE(format)*len);
-
-         if(silence) delete silence;
-         mSilentLog=TRUE;
-
-         return len;
-      }
-      if(silence) delete silence;
       mSilentLog=FALSE;
 
       sf_seek(sf, start, SEEK_SET);

src/effects/VST/VSTEffect.cpp

@@ -456,7 +456,7 @@ bool VSTEffectsModule::RegisterPlugin(PluginManagerInterface & pm, const wxStrin
    wxString effectIDs = wxT("0;");
    wxStringTokenizer effectTzr(effectIDs, wxT(";"));
 
-   wxProgressDialog *progress = NULL;
+   Maybe<wxProgressDialog> progress{};
    size_t idCnt = 0;
    size_t idNdx = 0;
 
@@ -517,16 +517,16 @@ bool VSTEffectsModule::RegisterPlugin(PluginManagerInterface & pm, const wxStrin
                idCnt = effectTzr.CountTokens();
                if (idCnt > 3)
                {
-                  progress = new wxProgressDialog(_("Scanning Shell VST"),
+                  progress.create( _("Scanning Shell VST"),
-                                                  wxString::Format(_("Registering %d of %d: %-64.64s"), 0, idCnt, proc.GetName().c_str()),
+                        wxString::Format(_("Registering %d of %d: %-64.64s"), 0, idCnt, proc.GetName().c_str()),
-                                                  idCnt,
+                        static_cast<int>(idCnt),
-                                                  NULL,
+                        nullptr,
-                                                  wxPD_APP_MODAL |
+                        wxPD_APP_MODAL |
-                                                  wxPD_AUTO_HIDE |
+                           wxPD_AUTO_HIDE |
-                                                  wxPD_CAN_ABORT |
+                           wxPD_CAN_ABORT |
-                                                  wxPD_ELAPSED_TIME |
+                           wxPD_ELAPSED_TIME |
-                                                  wxPD_ESTIMATED_TIME |
+                           wxPD_ESTIMATED_TIME |
-                                                  wxPD_REMAINING_TIME);
+                           wxPD_REMAINING_TIME );
                   progress->Show();
                }
             break;
@@ -611,11 +611,6 @@ bool VSTEffectsModule::RegisterPlugin(PluginManagerInterface & pm, const wxStrin
       }
    }
 
-   if (progress)
-   {
-      delete progress;
-   }
-
    return valid;
 }
 

src/import/ImportMP3.cpp

@@ -213,7 +213,7 @@ int MP3ImportFileHandle::Import(TrackFactory *trackFactory, Track ***outTracks,
 
    mPrivateData.file        = mFile;
    mPrivateData.inputBuffer = new unsigned char [INPUT_BUFFER_SIZE];
-   mPrivateData.progress    = mProgress;
+   mPrivateData.progress    = mProgress.get();
    mPrivateData.channels    = NULL;
    mPrivateData.updateResult= eProgressSuccess;
    mPrivateData.id3checked  = false;

src/import/ImportPlugin.h

@@ -119,17 +119,12 @@ class ImportFileHandle /* not final */
 public:
    ImportFileHandle(const wxString & filename)
    :  mFilename(filename),
-   mProgress(NULL)
+   mProgress{}
    {
    }
 
    virtual ~ImportFileHandle()
    {
-      if (mProgress != NULL)
-      {
-         delete mProgress;
-         mProgress = NULL;
-      }
    }
 
    // The importer should call this to create the progress dialog and
@@ -140,8 +135,7 @@ public:
       wxString title;
 
       title.Printf(_("Importing %s"), GetFileDescription().c_str());
-      mProgress = new ProgressDialog(title,
+      mProgress.create(title, f.GetFullName());
-                                     f.GetFullName());
    }
 
    // This is similar to GetImporterDescription, but if possible the
@@ -170,7 +164,7 @@ public:
 
 protected:
    wxString mFilename;
-   ProgressDialog *mProgress;
+   Maybe<ProgressDialog> mProgress;
 };