diff options
author | Stephen Kelly <stephen.kelly@kdab.com> | 2012-03-02 14:48:09 +0100 |
---|---|---|
committer | Qt by Nokia <qt-info@nokia.com> | 2012-03-06 13:37:17 +0100 |
commit | eb24dfcccb304c84a147f0eafd3b3fc3df3ef4f3 (patch) | |
tree | 24f6ed9f377f52a69006488ba24af4762581105b /src/corelib/kernel | |
parent | 9a5c728e4664cdd22ab999a9c7c15b7ed4965ce1 (diff) |
Add template specialization of QMetaType for QObject derived pointers.
This makes it possible to do things like
QVariant::fromValue(new SomeObject);
without first using Q_DECLARE_METATYPE(Something*)
This functionality was originally part of
http://codereview.qt-project.org/#change,11710 but was rejected
because the functionality was based on specialization of
QVariant::fromValue which could be dangerous.
This new implementation doesn't have such danger.
Change-Id: I83fe941b6984be54469bc6b9191f6eacaceaa036
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@nokia.com>
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Diffstat (limited to 'src/corelib/kernel')
-rw-r--r-- | src/corelib/kernel/qmetatype.h | 75 |
1 files changed, 51 insertions, 24 deletions
diff --git a/src/corelib/kernel/qmetatype.h b/src/corelib/kernel/qmetatype.h index f969875455..06ada136a6 100644 --- a/src/corelib/kernel/qmetatype.h +++ b/src/corelib/kernel/qmetatype.h @@ -364,33 +364,11 @@ void qMetaTypeLoadHelper(QDataStream &stream, void *t) template <> inline void qMetaTypeLoadHelper<void>(QDataStream &, void *) {} #endif // QT_NO_DATASTREAM -template <typename T> -struct QMetaTypeId -{ - enum { Defined = 0 }; -}; - -template <typename T> -struct QMetaTypeId2 -{ - enum { Defined = QMetaTypeId<T>::Defined }; - static inline int qt_metatype_id() { return QMetaTypeId<T>::qt_metatype_id(); } -}; - class QObject; class QWidget; -namespace QtPrivate { - template <typename T, bool Defined = QMetaTypeId2<T>::Defined> - struct QMetaTypeIdHelper { - static inline int qt_metatype_id() - { return QMetaTypeId2<T>::qt_metatype_id(); } - }; - template <typename T> struct QMetaTypeIdHelper<T, false> { - static inline int qt_metatype_id() - { return -1; } - }; - +namespace QtPrivate +{ template<typename T> struct IsPointerToTypeDerivedFromQObject { @@ -427,6 +405,38 @@ namespace QtPrivate { Q_STATIC_ASSERT_X(sizeof(T), "Type argument of Q_DECLARE_METATYPE(T*) must be fully defined"); enum { Value = sizeof(checkType(static_cast<T*>(0))) == sizeof(yes_type) }; }; +} + +template <typename T, bool = QtPrivate::IsPointerToTypeDerivedFromQObject<T>::Value> +struct QMetaTypeIdQObject +{ + enum { + Defined = 0 + }; +}; + +template <typename T> +struct QMetaTypeId : public QMetaTypeIdQObject<T> +{ +}; + +template <typename T> +struct QMetaTypeId2 +{ + enum { Defined = QMetaTypeId<T>::Defined }; + static inline int qt_metatype_id() { return QMetaTypeId<T>::qt_metatype_id(); } +}; + +namespace QtPrivate { + template <typename T, bool Defined = QMetaTypeId2<T>::Defined> + struct QMetaTypeIdHelper { + static inline int qt_metatype_id() + { return QMetaTypeId2<T>::qt_metatype_id(); } + }; + template <typename T> struct QMetaTypeIdHelper<T, false> { + static inline int qt_metatype_id() + { return -1; } + }; // Function pointers don't derive from QObject template <class Result> struct IsPointerToTypeDerivedFromQObject<Result(*)()> { enum { Value = false }; }; @@ -501,6 +511,23 @@ inline int qRegisterMetaType( #endif } +template <typename T> +struct QMetaTypeIdQObject<T*, /* isPointerToTypeDerivedFromQObject */ true> +{ + enum { + Defined = 1 + }; + + static int qt_metatype_id() + { + static QBasicAtomicInt metatype_id = Q_BASIC_ATOMIC_INITIALIZER(0); + if (!metatype_id.load()) + metatype_id.storeRelease(qRegisterMetaType<T*>(QByteArray(T::staticMetaObject.className() + QByteArrayLiteral("*")).constData(), + reinterpret_cast<T**>(quintptr(-1)))); + return metatype_id.loadAcquire(); + } +}; + #ifndef QT_NO_DATASTREAM template <typename T> inline int qRegisterMetaTypeStreamOperators() |