libdeng2: Utility for the pimpl idiom

The DENG2_PIMPL macro makes it somewhat easier to define a private implementation struct that contains a reference to the public instance.
skyjake · Feb 7, 2013 · 3534776 · 3534776
1 parent 3972ce0
commit 3534776
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Showing 8 changed files with 59 additions and 41 deletions.
diff --git a/doomsday/libdeng2/include/de/libdeng2.h b/doomsday/libdeng2/include/de/libdeng2.h
@@ -205,9 +205,35 @@
 #define DENG2_FOR_EACH_CONST_REVERSE(IterClass, Var, ContainerRef) \
     for(IterClass::const_reverse_iterator Var = (ContainerRef).rbegin(); Var != (ContainerRef).rend(); ++Var)
 
-#if defined(__cplusplus) && !defined(DENG2_C_API_ONLY)
+/**
+ * Macro for starting the definition of a private implementation struct. Example:
+ * <pre>
+ *    DENG2_PIMPL(MyClass)
+ *    {
+ *        Instance(Public &inst) : Private(inst) {
+ *            // constructor
+ *        }
+ *        // private data and methods
+ *    };
+ * </pre>
+ */
+#define DENG2_PIMPL(ClassName) \
+    typedef ClassName Public; \
+    struct ClassName::Instance : public de::Private<ClassName>
+
+#if defined __cplusplus
 namespace de {
 
+/**
+ * Utility template for defining private implementation data (pimpl idiom). Use
+ * this in source files, not in headers.
+ */
+template <typename Type>
+struct Private {
+    Type &self;
+    Private(Type &i) : self(i) {}
+};
+
 template <typename FromType, typename ToType>
 inline ToType function_cast(FromType ptr)
 {
@@ -223,6 +249,12 @@ inline ToType function_cast(FromType ptr)
     return forcedCast.target;
 }
 
+} // namespace de
+#endif // __cplusplus
+
+#if defined __cplusplus && !defined DENG2_C_API_ONLY
+namespace de {
+
 /**
  * All serialization in all contexts use a common protocol version number.
  * Whenever anything changes in serialization, the protocol version needs to be

diff --git a/doomsday/libdeng2/src/core/app.cpp b/doomsday/libdeng2/src/core/app.cpp
@@ -41,10 +41,8 @@ namespace de {
 
 static App *singletonApp;
 
-struct App::Instance : DENG2_OBSERVES(Record, Deletion)
+DENG2_PIMPL(App), DENG2_OBSERVES(Record, Deletion)
 {
-    App &app;
-
     CommandLine cmdLine;
 
     LogBuffer logBuffer;
@@ -83,8 +81,8 @@ struct App::Instance : DENG2_OBSERVES(Record, Deletion)
 
     void (*terminateFunc)(char const *);
 
-    Instance(App &a, QStringList args)
-        : app(a), cmdLine(args), persistentData(0), config(0), terminateFunc(0)
+    Instance(Public &a, QStringList args)
+        : Private(a), cmdLine(args), persistentData(0), config(0), terminateFunc(0)
     {
         singletonApp = &a;
 
@@ -126,10 +124,10 @@ struct App::Instance : DENG2_OBSERVES(Record, Deletion)
         binFolder.attach(new DirectoryFeed(appDir));
         if(allowPlugins)
         {
-            binFolder.attach(new DirectoryFeed(app.nativePluginBinaryPath()));
+            binFolder.attach(new DirectoryFeed(self.nativePluginBinaryPath()));
         }
-        fs.makeFolder("/data").attach(new DirectoryFeed(app.nativeBasePath()));
-        fs.makeFolder("/modules").attach(new DirectoryFeed(app.nativeBasePath() / "modules"));
+        fs.makeFolder("/data").attach(new DirectoryFeed(self.nativeBasePath()));
+        fs.makeFolder("/modules").attach(new DirectoryFeed(self.nativeBasePath() / "modules"));
 
 #elif WIN32
         if(allowPlugins)
@@ -150,7 +148,7 @@ struct App::Instance : DENG2_OBSERVES(Record, Deletion)
 #endif
 
         // User's home folder.
-        fs.makeFolder("/home").attach(new DirectoryFeed(app.nativeHomePath(),
+        fs.makeFolder("/home").attach(new DirectoryFeed(self.nativeHomePath(),
             DirectoryFeed::AllowWrite | DirectoryFeed::CreateIfMissing));
 
         // Populate the file system.

diff --git a/doomsday/libdeng2/src/core/commandline.cpp b/doomsday/libdeng2/src/core/commandline.cpp
@@ -43,7 +43,7 @@ static char *duplicateStringAsUtf8(QString const &s)
     return copy;
 }
 
-struct CommandLine::Instance
+DENG2_PIMPL(CommandLine)
 {
     QDir initialDir;
 
@@ -57,7 +57,7 @@ struct CommandLine::Instance
     typedef std::map<std::string, ArgumentStrings> Aliases;
     Aliases aliases;
 
-    Instance()
+    Instance(Public &i) : Private(i)
     {
         initialDir = QDir::current();
     }
@@ -122,15 +122,11 @@ struct CommandLine::Instance
     }
 };
 
-CommandLine::CommandLine()
-{
-    d = new Instance;
-}
+CommandLine::CommandLine() : d(new Instance(*this))
+{}
 
-CommandLine::CommandLine(QStringList const &args)
+CommandLine::CommandLine(QStringList const &args) : d(new Instance(*this))
 {
-    d = new Instance;
-
     for(int i = 0; i < args.size(); ++i)
     {
         if(args.at(i)[0] == '@')
@@ -145,10 +141,8 @@ CommandLine::CommandLine(QStringList const &args)
     }
 }
 
-CommandLine::CommandLine(CommandLine const &other)
+CommandLine::CommandLine(CommandLine const &other) : d(new Instance(*this))
 {
-    d = new Instance;
-
     DENG2_FOR_EACH_CONST(Instance::Arguments, i, other.d->arguments)
     {
         d->appendArg(*i);

diff --git a/doomsday/libshell/src/choicewidget.cpp b/doomsday/libshell/src/choicewidget.cpp
@@ -23,15 +23,14 @@
 namespace de {
 namespace shell {
 
-struct ChoiceWidget::Instance
+DENG2_PIMPL(ChoiceWidget)
 {
-    ChoiceWidget &self;
     Items items;
     int selection;
     MenuWidget *menu;
     String prompt;
 
-    Instance(ChoiceWidget &inst) : self(inst), selection(0)
+    Instance(Public &i) : Private(i), selection(0)
     {}
 
     void updateMenu()

diff --git a/doomsday/libshell/src/commandlinewidget.cpp b/doomsday/libshell/src/commandlinewidget.cpp
@@ -24,10 +24,8 @@
 namespace de {
 namespace shell {
 
-struct CommandLineWidget::Instance
+DENG2_PIMPL(CommandLineWidget)
 {
-    CommandLineWidget &self;
-
     /**
      * Line of text with a cursor.
      */
@@ -44,7 +42,7 @@ struct CommandLineWidget::Instance
     QList<Command> history;
     int historyPos;
 
-    Instance(CommandLineWidget &cli) : self(cli), historyPos(0)
+    Instance(Public &i) : Private(i), historyPos(0)
     {
         history.append(Command());
     }

diff --git a/doomsday/libshell/src/lineeditwidget.cpp b/doomsday/libshell/src/lineeditwidget.cpp
@@ -28,9 +28,8 @@
 namespace de {
 namespace shell {
 
-struct LineEditWidget::Instance
+DENG2_PIMPL(LineEditWidget)
 {
-    LineEditWidget &self;
     ConstantRule *height;
     bool signalOnEnter;
     String prompt;
@@ -56,8 +55,8 @@ struct LineEditWidget::Instance
     // Word wrapping.
     LineWrapping wraps;
 
-    Instance(LineEditWidget &cli)
-        : self(cli),
+    Instance(Public &i)
+        : Private(i),
           signalOnEnter(true),
           cursor(0)
     {

diff --git a/doomsday/libshell/src/link.cpp b/doomsday/libshell/src/link.cpp
@@ -27,9 +27,8 @@
 namespace de {
 namespace shell {
 
-struct Link::Instance
+DENG2_PIMPL(Link)
 {
-    Link &self;
     String tryingToConnectToHost;
     Time startedTryingAt;
     TimeDelta timeout;
@@ -39,8 +38,8 @@ struct Link::Instance
     Status status;
     Time connectedAt;
 
-    Instance(Link &i)
-        : self(i),
+    Instance(Public &i)
+        : Private(i),
           socket(0),
           status(Disconnected),
           connectedAt(Time::invalidTime()) {}

diff --git a/doomsday/libshell/src/menuwidget.cpp b/doomsday/libshell/src/menuwidget.cpp
@@ -24,9 +24,8 @@
 namespace de {
 namespace shell {
 
-struct MenuWidget::Instance
+DENG2_PIMPL(MenuWidget)
 {
-    MenuWidget &self;
     ConstantRule *width;
     ConstantRule *height;
     TextCanvas::Char::Attribs borderAttr;
@@ -50,8 +49,8 @@ struct MenuWidget::Instance
     QList<Item> items;
     int cursor;
 
-    Instance(MenuWidget &inst)
-        : self(inst),
+    Instance(Public &i)
+        : Private(i),
           borderAttr(TextCanvas::Char::Reverse),
           backgroundAttr(TextCanvas::Char::Reverse),
           borderStyle(LineBorder),