Fix Preferences Buttons

src/preferences/dlgpreferencepage.h

@@ -1,41 +1,39 @@
-#ifndef DLGPREFERENCEPAGE_H
-#define DLGPREFERENCEPAGE_H
+#pragma once
 
 #include <QWidget>
 
-// API that all preference pages should implement.
+/// Interface that all preference pages have to implement.
 class DlgPreferencePage : public QWidget {
     Q_OBJECT
   public:
     DlgPreferencePage(QWidget* pParent);
     virtual ~DlgPreferencePage();
 
   public slots:
-    // Called when the preference dialog is shown to the user (not necessarily
-    // when this PreferencePage is shown to the user). At this point, the
-    // PreferencePage should update all of its setting to the latest values.
-    virtual void slotUpdate() {}
-
-    // Called when the user clicks the global "Apply" button. The preference
-    // dialog should make all of the current setting of the UI widgets active.
-    virtual void slotApply() {}
-
-    // Called when the user clicks the global "Cancel" button. The preference
-    // dialog should revert all of the changes the user made since the last
-    // slotUpdate.
-    virtual void slotCancel() {}
-
-    // Called when the user clicks the global "Reset to Defaults" button. The
-    // preference dialog should revert settings to their default values.
-    virtual void slotResetToDefaults() {}
-
-    // Called when the preferences dialog is shown to the user (not necessarily
-    // when this PreferencePage is shown to the user).
+    /// Called when the preference dialog is shown to the user (not necessarily
+    /// when this PreferencePage is shown to the user). At this point, the
+    /// PreferencePage should update all of its setting to the latest values.
+    virtual void slotUpdate() = 0;
+
+    /// Called when the user clicks the global "Apply" button. The preference
+    /// dialog should make all of the current setting of the UI widgets active.
+    virtual void slotApply() = 0;
+
+    /// Called when the user clicks the global "Cancel" button. The preference
+    /// dialog should revert all of the changes the user made since the last
+    /// slotUpdate. The default implementation just class slotUpdate.
+    virtual void slotCancel() {
+        slotUpdate();
+    }
+
+    /// Called when the user clicks the global "Reset to Defaults" button. The
+    /// preference dialog should revert settings to their default values.
+    virtual void slotResetToDefaults() = 0;
+
+    /// Called when the preferences dialog is shown to the user (not necessarily
+    /// when this PreferencePage is shown to the user).
     virtual void slotShow() {}
 
-    // Called when the preferences dialog is hidden from the user.
+    /// Called when the preferences dialog is hidden from the user.
     virtual void slotHide() {}
 };
-
-
-#endif /* DLGPREFERENCEPAGE_H */