Hide two-phase construction of AudacityFileConfig in factory function

src/AudacityApp.cpp

@@ -189,11 +189,10 @@ void PopulatePreferences()
    {
       const wxString fullPath{fn.GetFullPath()};
 
-      AudacityFileConfig ini(wxEmptyString,
-                     wxEmptyString,
-                     fullPath,
-                     wxEmptyString,
-                     wxCONFIG_USE_LOCAL_FILE);
+      auto pIni =
+         AudacityFileConfig::Create({}, {}, fullPath, {},
+            wxCONFIG_USE_LOCAL_FILE);
+      auto &ini = *pIni;
 
       wxString lang;
       if (ini.Read(wxT("/FromInno/Language"), &lang))
@@ -1249,7 +1248,7 @@ bool AudacityApp::OnInit()
    {
       wxFileName configFileName(FileNames::DataDir(), wxT("audacity.cfg"));
       auto appName = wxTheApp->GetAppName();
-      InitPreferences( std::make_unique<AudacityFileConfig>(
+      InitPreferences( AudacityFileConfig::Create(
          appName, wxEmptyString,
          configFileName.GetFullPath(),
          wxEmptyString, wxCONFIG_USE_LOCAL_FILE) );

src/AudacityFileConfig.cpp

@@ -8,6 +8,35 @@ Paul Licameli split from Prefs.cpp
 
 **********************************************************************/
 
+#include "Audacity.h"
 #include "AudacityFileConfig.h"
 
+AudacityFileConfig::AudacityFileConfig(
+   const wxString& appName,
+   const wxString& vendorName,
+   const wxString& localFilename,
+   const wxString& globalFilename,
+   long style,
+   const wxMBConv& conv
+)
+: FileConfig{ appName, vendorName, localFilename, globalFilename, style, conv }
+{}
+
 AudacityFileConfig::~AudacityFileConfig() = default;
+
+std::unique_ptr<AudacityFileConfig> AudacityFileConfig::Create(
+   const wxString& appName,
+   const wxString& vendorName,
+   const wxString& localFilename,
+   const wxString& globalFilename,
+   long style,
+   const wxMBConv& conv
+)
+{
+   // Private ctor means make_unique can't compile, so this verbosity:
+   auto result = std::unique_ptr<AudacityFileConfig>{
+      safenew AudacityFileConfig{
+         appName, vendorName, localFilename, globalFilename, style, conv } };
+   result->Init();
+   return result;
+}

src/AudacityFileConfig.h

@@ -12,14 +12,34 @@ Paul Licameli split from Prefs.h
 #ifndef __AUDACITY_FILE_CONFIG__
 #define __AUDACITY_FILE_CONFIG__
 
+#include <memory>
 #include "widgets/FileConfig.h" // to inherit
 
-/// \brief Our own specialisation of FileConfig.  It is essentially a renaming.
+/// \brief Our own specialisation of FileConfig.
 class AUDACITY_DLL_API AudacityFileConfig final : public FileConfig
 {
 public:
-   using FileConfig::FileConfig;
+   //! Require a call to this factory, to guarantee proper two-phase initialization
+   static std::unique_ptr<AudacityFileConfig> Create(
+      const wxString& appName = {},
+      const wxString& vendorName = {},
+      const wxString& localFilename = {},
+      const wxString& globalFilename = {},
+      long style = wxCONFIG_USE_LOCAL_FILE | wxCONFIG_USE_GLOBAL_FILE,
+      const wxMBConv& conv = wxConvAuto()
+   );
 
    ~AudacityFileConfig() override;
+
+private:
+   //! Disallow direct constructor call, because a two-phase initialization is required
+   AudacityFileConfig(
+      const wxString& appName,
+      const wxString& vendorName,
+      const wxString& localFilename,
+      const wxString& globalFilename,
+      long style,
+      const wxMBConv& conv
+   );
 };
 #endif

src/PluginManager.cpp

@@ -1930,8 +1930,9 @@ bool PluginManager::DropFile(const wxString &fileName)
 void PluginManager::Load()
 {
    // Create/Open the registry
-   AudacityFileConfig registry(
+   auto pRegistry = AudacityFileConfig::Create(
       {}, {}, FileNames::PluginRegistry());
+   auto &registry = *pRegistry;
 
    // If this group doesn't exist then we have something that's not a registry.
    // We should probably warn the user, but it's pretty unlikely that this will happen.
@@ -2272,8 +2273,9 @@ void PluginManager::LoadGroup(FileConfig *pRegistry, PluginType type)
 void PluginManager::Save()
 {
    // Create/Open the registry
-   AudacityFileConfig registry(
+   auto pRegistry = AudacityFileConfig::Create(
       {}, {}, FileNames::PluginRegistry());
+   auto &registry = *pRegistry;
 
    // Clear it out
    registry.DeleteAll();
@@ -2780,7 +2782,8 @@ FileConfig *PluginManager::GetSettings()
 {
    if (!mSettings)
    {
-      mSettings = std::make_unique<AudacityFileConfig>(wxEmptyString, wxEmptyString, FileNames::PluginSettings());
+      mSettings =
+         AudacityFileConfig::Create({}, {}, FileNames::PluginSettings());
 
       // Check for a settings version that we can understand
       if (mSettings->HasEntry(SETVERKEY))

src/widgets/FileConfig.cpp

@@ -45,6 +45,10 @@ FileConfig::FileConfig(const wxString& appName,
 :  wxFileConfig(appName, vendorName, localFilename, globalFilename, style, conv),
    mConfigPath(localFilename),
    mDirty(false)
+{
+}
+
+void FileConfig::Init()
 {
    // Prevent wxFileConfig from attempting a Flush() during object deletion. This happens
    // because we don't use the wxFileConfig::Flush() method and so the wxFileConfig dirty

src/widgets/FileConfig.h

@@ -25,6 +25,7 @@ public:
               const wxString& globalFilename = wxEmptyString,
               long style = wxCONFIG_USE_LOCAL_FILE | wxCONFIG_USE_GLOBAL_FILE,
               const wxMBConv& conv = wxConvAuto());
+   void Init();
    virtual ~FileConfig();
 
    virtual bool Flush(bool bCurrentOnly = false) wxOVERRIDE;