Define Setting classes, bundling config path with settings value...

... the intention being, that no string literal for a path, or its default value, shall ever occur twice in the code, relying on long-distance coincidence of literal values. Instead, a named Setting object is constructed once, then read and written. For now, the Tie... functions in ShuttleGuiBase will take references to implicitly constructed temporary Setting objects. But all should later be made static objects, and the constructors made explicit.
TYoung86 · May 17, 2021 · 5fef82d · 5fef82d
1 parent b6c7b74
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Showing 9 changed files with 240 additions and 52 deletions.
diff --git a/src/Prefs.cpp b/src/Prefs.cpp
@@ -280,7 +280,7 @@ bool ChoiceSetting::Write( const wxString &value )
 }
 
 EnumSettingBase::EnumSettingBase(
-   const wxString &key,
+   const SettingBase &key,
    EnumValueSymbols symbols,
    long defaultSymbol,
 
@@ -398,3 +398,23 @@ void PreferenceInitializer::ReinitializeAll()
    for ( auto pInitializer : allInitializers() )
       (*pInitializer)();
 }
+
+wxConfigBase *SettingBase::GetConfig() const
+{
+   return gPrefs;
+}
+
+bool SettingBase::Delete()
+{
+   auto config = GetConfig();
+   return config && config->DeleteEntry( GetPath() );
+}
+
+bool BoolSetting::Toggle()
+{
+   bool value = Read();
+   if ( Write( !value ) )
+      return !value;
+   else
+      return value;
+}
diff --git a/src/Prefs.h b/src/Prefs.h
@@ -36,6 +36,8 @@
 // the second part (after the r) indicates the number of times the prefs have been reset within the same version
 #define AUDACITY_PREFS_VERSION_STRING "1.1.1r1"
 
+#include <functional>
+
 #include "../include/audacity/ComponentInterface.h"
 #include "MemoryX.h" // for wxArrayStringEx
 #include "widgets/FileConfig.h"
@@ -55,6 +57,168 @@ extern int gMenusDirty;
 struct ByColumns_t{};
 extern ByColumns_t ByColumns;
 
+//! Base class for settings objects.  It holds a configuration key path.
+/* The constructors are non-explicit for convenience */
+class AUDACITY_DLL_API SettingBase
+{
+public:
+   SettingBase( const char *path ) : mPath{ path } {}
+   SettingBase( const wxChar *path ) : mPath{ path } {}
+   SettingBase( const wxString &path ) : mPath{ path } {}
+
+   wxConfigBase *GetConfig() const;
+
+   const wxString &GetPath() const { return mPath; }
+
+   //! Delete the key if present, and return true iff it was.
+   bool Delete();
+
+protected:
+   SettingBase( const SettingBase& ) = default;
+   const RegistryPath mPath;
+};
+
+//! Class template adds an in-memory cache of a value to SettingBase.
+template< typename T >
+class CachingSettingBase : public SettingBase
+{
+public:
+   explicit CachingSettingBase( const SettingBase &path )
+      : SettingBase{ path } {}
+protected:
+   CachingSettingBase( const CachingSettingBase & ) = default;
+   mutable T mCurrentValue{};
+   mutable bool mValid{false};
+};
+
+//! Class template adds default value, read, and write methods to CachingSetingBase
+template< typename T >
+class Setting : public CachingSettingBase< T >
+{
+public:
+   using CachingSettingBase< T >::CachingSettingBase;
+
+   using DefaultValueFunction = std::function< T() >;
+
+   //! Usual overload supplies a default value
+   Setting( const SettingBase &path, const T &defaultValue )
+      : CachingSettingBase< T >{ path }
+      , mDefaultValue{ defaultValue }
+   {}
+
+   //! This overload causes recomputation of the default each time it is needed
+   Setting( const SettingBase &path, DefaultValueFunction function )
+      : CachingSettingBase< T >{ path }
+      , mFunction{ function }
+   {}
+
+
+   const T& GetDefault() const
+   {
+      if ( mFunction )
+         mDefaultValue = mFunction();
+      return mDefaultValue;
+   }
+
+   //! overload of Read returning a success flag
+   /*! The cache is unchanged if that is false */
+   bool Read( T *pVar ) const
+   {
+      if ( pVar && this->mValid ) {
+         *pVar = this->mCurrentValue;
+         return true;
+      }
+      const auto config = this->GetConfig();
+      if ( pVar && config ) {
+         if ((this->mValid = config->Read( this->mPath, &this->mCurrentValue )))
+            *pVar = this->mCurrentValue;
+         return this->mValid;
+      }
+      return (this->mValid = false);
+   }
+
+   //! overload of Read, always returning a value
+   /*! The value is the default stored in this in case the key is known to be absent from the config;
+    but it returns type T's default value if there was failure to read the config */
+   T Read() const
+   {
+      return ReadWithDefault( GetDefault() );
+   }
+
+   //! new direct use is discouraged but it may be needed in legacy code
+   /*! Use the given default in case the preference is not defined, which may not be the
+    default-default stored in this object. */
+   T ReadWithDefault( const T &defaultValue ) const
+   {
+      const auto config = this->GetConfig();
+      return config
+         ? ( this->mValid = true, this->mCurrentValue =
+               config->ReadObject( this->mPath, defaultValue ) )
+         : T{};
+   }
+
+   //! Write value to config and return true if successful
+   bool Write( const T &value )
+   {
+      const auto config = this->GetConfig();
+      if ( config ) {
+         this->mCurrentValue = value;
+         return DoWrite();
+      }
+      return false;
+   }
+
+   //! Reset to the default value
+   bool Reset()
+   {
+      return Write( GetDefault() );
+   }
+
+protected:
+   //! Write cached value to config and return true if successful
+   /*! (But the config object is not flushed) */
+   bool DoWrite( )
+   {
+      const auto config = this->GetConfig();
+      return this->mValid =
+         config ? config->Write( this->mPath, this->mCurrentValue ) : false;
+   }
+
+   mutable T mDefaultValue{};
+   const DefaultValueFunction mFunction;
+};
+
+//! This specialization of Setting for bool adds a Toggle method to negate the saved value
+class BoolSetting final : public Setting< bool >
+{
+public:
+   using Setting::Setting;
+
+   //! Write the negation of the previous value, and then return the current value.
+   bool Toggle();
+};
+
+//! Specialization of Setting for int
+class IntSetting final : public Setting< int >
+{
+public:
+   using Setting::Setting;
+};
+
+//! Specialization of Setting for double
+class DoubleSetting final : public Setting< double >
+{
+public:
+   using Setting::Setting;
+};
+
+//! Specialization of Setting for strings
+class StringSetting final : public Setting< wxString >
+{
+public:
+   using Setting::Setting;
+};
+
 /// A table of EnumValueSymbol that you can access by "row" with
 /// operator [] but also allowing access to the "columns" of internal or
 /// translated strings, and also allowing convenient column-wise construction
@@ -90,11 +254,11 @@ class AUDACITY_DLL_API ChoiceSetting
 {
 public:
    ChoiceSetting(
-      const wxString &key,
+      const SettingBase &key,
       EnumValueSymbols symbols,
       long defaultSymbol = -1
    )
-      : mKey{ key }
+      : mKey{ key.GetPath() }
 
       , mSymbols{ std::move( symbols ) }
 
@@ -140,7 +304,7 @@ class AUDACITY_DLL_API EnumSettingBase : public ChoiceSetting
 {
 public:
    EnumSettingBase(
-      const wxString &key,
+      const SettingBase &key,
       EnumValueSymbols symbols,
       long defaultSymbol,
 
@@ -175,7 +339,7 @@ class EnumSetting : public EnumSettingBase
 public:
 
    EnumSetting(
-      const wxString &key,
+      const SettingBase &key,
       EnumValueSymbols symbols,
       long defaultSymbol,
 

diff --git a/src/ShuttleGui.cpp b/src/ShuttleGui.cpp
@@ -1815,7 +1815,7 @@ bool ShuttleGuiBase::DoStep( int iStep )
 /// between gui and stack variable and stack variable and shuttle.
 wxCheckBox * ShuttleGuiBase::TieCheckBox(
    const TranslatableString &Prompt,
-   const SettingSpec< bool > &Setting)
+   const BoolSetting &Setting)
 {
    wxCheckBox * pCheck=NULL;
 
@@ -1832,7 +1832,7 @@ wxCheckBox * ShuttleGuiBase::TieCheckBox(
 /// between gui and stack variable and stack variable and shuttle.
 wxCheckBox * ShuttleGuiBase::TieCheckBoxOnRight(
    const TranslatableString &Prompt,
-   const SettingSpec< bool > &Setting)
+   const BoolSetting & Setting)
 {
    wxCheckBox * pCheck=NULL;
 
@@ -1849,7 +1849,7 @@ wxCheckBox * ShuttleGuiBase::TieCheckBoxOnRight(
 /// between gui and stack variable and stack variable and shuttle.
 wxSlider * ShuttleGuiBase::TieSlider(
    const TranslatableString &Prompt,
-   const SettingSpec< int > &Setting,
+   const IntSetting & Setting,
    const int max,
    const int min)
 {
@@ -1868,7 +1868,7 @@ wxSlider * ShuttleGuiBase::TieSlider(
 /// between gui and stack variable and stack variable and shuttle.
 wxSpinCtrl * ShuttleGuiBase::TieSpinCtrl(
    const TranslatableString &Prompt,
-   const SettingSpec< int > &Setting,
+   const IntSetting &Setting,
    const int max,
    const int min)
 {
@@ -1887,7 +1887,7 @@ wxSpinCtrl * ShuttleGuiBase::TieSpinCtrl(
 /// between gui and stack variable and stack variable and shuttle.
 wxTextCtrl * ShuttleGuiBase::TieTextBox(
    const TranslatableString & Prompt,
-   const SettingSpec< wxString > &Setting,
+   const StringSetting & Setting,
    const int nChars)
 {
    wxTextCtrl * pText=(wxTextCtrl*)NULL;
@@ -1905,7 +1905,7 @@ wxTextCtrl * ShuttleGuiBase::TieTextBox(
 /// This one does it for double values...
 wxTextCtrl * ShuttleGuiBase::TieIntegerTextBox(
    const TranslatableString & Prompt,
-   const SettingSpec< int > &Setting,
+   const IntSetting &Setting,
    const int nChars)
 {
    wxTextCtrl * pText=(wxTextCtrl*)NULL;
@@ -1923,7 +1923,7 @@ wxTextCtrl * ShuttleGuiBase::TieIntegerTextBox(
 /// This one does it for double values...
 wxTextCtrl * ShuttleGuiBase::TieNumericTextBox(
    const TranslatableString & Prompt,
-   const SettingSpec< double > &Setting,
+   const DoubleSetting & Setting,
    const int nChars)
 {
    wxTextCtrl * pText=(wxTextCtrl*)NULL;
@@ -1984,7 +1984,7 @@ wxChoice *ShuttleGuiBase::TieChoice(
 ///                             if null, then use 0, 1, 2, ...
 wxChoice * ShuttleGuiBase::TieNumberAsChoice(
    const TranslatableString &Prompt,
-   const SettingSpec< int > &Setting,
+   const IntSetting & Setting,
    const TranslatableStrings & Choices,
    const std::vector<int> * pInternalChoices,
    int iNoMatchSelector)

diff --git a/src/ShuttleGui.h b/src/ShuttleGui.h
@@ -22,6 +22,7 @@
 #include "MemoryX.h"
 #include <wx/listbase.h> // for wxLIST_FORMAT_LEFT
 
+#include "Prefs.h"
 #include "WrappedType.h"
 
 class ChoiceSetting;
@@ -103,20 +104,6 @@ using wxStaticBoxWrapper = wxStaticBox;
 using wxSliderWrapper = wxSlider;
 #endif
 
-template< typename T > class SettingSpec {
-public:
-   SettingSpec( const RegistryPath &path, const T &defaultValue = {} )
-      : mPath{ path }, mDefaultValue{ defaultValue }
-   {}
-
-   const RegistryPath &GetPath() const { return mPath; }
-   const T &GetDefault() const { return mDefaultValue; }
-
-private:
-   RegistryPath mPath;
-   T mDefaultValue;
-};
-
 namespace DialogDefinition {
 
 struct Item {
@@ -450,10 +437,10 @@ class AUDACITY_DLL_API ShuttleGuiBase /* not final */
 // so it doesn't need an argument that is writeable.
    virtual wxCheckBox * TieCheckBox(
       const TranslatableString &Prompt,
-      const SettingSpec< bool > &Setting);
+      const BoolSetting &Setting);
    virtual wxCheckBox * TieCheckBoxOnRight(
       const TranslatableString &Prompt,
-      const SettingSpec< bool > &Setting);
+      const BoolSetting &Setting);
 
    virtual wxChoice *TieChoice(
       const TranslatableString &Prompt,
@@ -466,31 +453,31 @@ class AUDACITY_DLL_API ShuttleGuiBase /* not final */
    // emitting scripting information about Preferences.
    virtual wxChoice * TieNumberAsChoice(
       const TranslatableString &Prompt,
-      const SettingSpec< int > &Setting,
+      const IntSetting &Setting,
       const TranslatableStrings & Choices,
       const std::vector<int> * pInternalChoices = nullptr,
       int iNoMatchSelector = 0 );
 
    virtual wxTextCtrl * TieTextBox(
       const TranslatableString &Prompt,
-      const SettingSpec< wxString > &Setting,
+      const StringSetting &Setting,
       const int nChars);
    virtual wxTextCtrl * TieIntegerTextBox(
       const TranslatableString & Prompt,
-      const SettingSpec< int > &Setting,
+      const IntSetting &Setting,
       const int nChars);
    virtual wxTextCtrl * TieNumericTextBox(
       const TranslatableString & Prompt,
-      const SettingSpec< double > &Setting,
+      const DoubleSetting &Setting,
       const int nChars);
    virtual wxSlider * TieSlider(
       const TranslatableString & Prompt,
-      const SettingSpec< int > &Setting,
+      const IntSetting &Setting,
       const int max,
       const int min = 0);
    virtual wxSpinCtrl * TieSpinCtrl(
       const TranslatableString &Prompt,
-      const SettingSpec< int > &Setting,
+      const IntSetting &Setting,
       const int max,
       const int min);
 //-- End of variants.