QMetaProperty Class
The QMetaProperty class provides meta-data about a property. More...
| Header: | #include <QMetaProperty> |
| CMake: | find_package(Qt6 REQUIRED COMPONENTS Core)target_link_libraries(mytarget PRIVATE Qt6::Core) |
| qmake: | QT += core |
Public Functions
(since 6.0) QUntypedBindable | bindable(QObject *object) const |
| QMetaEnum | enumerator() const |
| bool | hasNotifySignal() const |
(since 6.0) bool | isBindable() const |
| bool | isConstant() const |
| bool | isDesignable() const |
| bool | isEnumType() const |
| bool | isFinal() const |
| bool | isFlagType() const |
| bool | isReadable() const |
| bool | isRequired() const |
| bool | isResettable() const |
| bool | isScriptable() const |
| bool | isStored() const |
| bool | isUser() const |
| bool | isValid() const |
| bool | isWritable() const |
(since 6.0) QMetaType | metaType() const |
| const char * | name() const |
| QMetaMethod | notifySignal() const |
| int | notifySignalIndex() const |
| int | propertyIndex() const |
| QVariant | read(const QObject *object) const |
| QVariant | readOnGadget(const void *gadget) const |
| int | relativePropertyIndex() const |
| bool | reset(QObject *object) const |
| bool | resetOnGadget(void *gadget) const |
| int | revision() const |
(since 6.0) int | typeId() const |
| const char * | typeName() const |
| int | userType() const |
| bool | write(QObject *object, const QVariant &value) const |
(since 6.6) bool | write(QObject *object, QVariant &&v) const |
| bool | writeOnGadget(void *gadget, const QVariant &value) const |
(since 6.6) bool | writeOnGadget(void *gadget, QVariant &&value) const |
Detailed Description
Property meta-data is obtained from an object's meta-object. See QMetaObject::property() and QMetaObject::propertyCount() for details.
Property Meta-Data
A property has a name() and a type(), as well as various attributes that specify its behavior: isReadable(), isWritable(), isDesignable(), isScriptable(), revision(), and isStored().
If the property is an enumeration, isEnumType() returns true; if the property is an enumeration that is also a flag (i.e. its values can be combined using the OR operator), isEnumType() and isFlagType() both return true. The enumerator for these types is available from enumerator().
The property's values are set and retrieved with read(), write(), and reset(); they can also be changed through QObject's set and get functions. See QObject::setProperty() and QObject::property() for details.
Copying and Assignment
QMetaProperty objects can be copied by value. However, each copy will refer to the same underlying property meta-data.
See also QMetaObject, QMetaEnum, QMetaMethod, and Qt's Property System.
Member Function Documentation
[since 6.0] QUntypedBindable QMetaProperty::bindable(QObject *object) const
Returns the bindable interface for the property on a given object.
If the property doesn't support bindings, the returned interface will be invalid.
This function was introduced in Qt 6.0.
See also QObjectBindableProperty, QProperty, and isBindable().
QMetaEnum QMetaProperty::enumerator() const
Returns the enumerator if this property's type is an enumerator type; otherwise the returned value is undefined.
See also isEnumType() and isFlagType().
bool QMetaProperty::hasNotifySignal() const
Returns true if this property has a corresponding change notify signal; otherwise returns false.
See also notifySignal().
[since 6.0] bool QMetaProperty::isBindable() const
Returns true if the Q_PROPERTY() exposes binding functionality; otherwise returns false.
This implies that you can create bindings that use this property as a dependency or install QPropertyObserver objects on this property. Unless the property is readonly, you can also set a binding on this property.
This function was introduced in Qt 6.0.
See also QProperty, isWritable(), and bindable().
bool QMetaProperty::isConstant() const
Returns true if the property is constant; otherwise returns false.
A property is constant if the Q_PROPERTY()'s CONSTANT attribute is set.
bool QMetaProperty::isDesignable() const
Returns false if the Q_PROPERTY()'s DESIGNABLE attribute is false; otherwise returns true.
See also isScriptable() and isStored().
bool QMetaProperty::isEnumType() const
Returns true if the property's type is an enumeration value; otherwise returns false.
See also enumerator() and isFlagType().
bool QMetaProperty::isFinal() const
Returns true if the property is final; otherwise returns false.
A property is final if the Q_PROPERTY()'s FINAL attribute is set.
bool QMetaProperty::isFlagType() const
Returns true if the property's type is an enumeration value that is used as a flag; otherwise returns false.
Flags can be combined using the OR operator. A flag type is implicitly also an enum type.
See also isEnumType(), enumerator(), and QMetaEnum::isFlag().
bool QMetaProperty::isReadable() const
Returns true if this property is readable; otherwise returns false.
See also isWritable(), read(), and isValid().
bool QMetaProperty::isRequired() const
Returns true if the property is required; otherwise returns false.
A property is final if the Q_PROPERTY()'s REQUIRED attribute is set.
bool QMetaProperty::isResettable() const
Returns true if this property can be reset to a default value; otherwise returns false.
See also reset().
bool QMetaProperty::isScriptable() const
Returns false if the Q_PROPERTY()'s SCRIPTABLE attribute is false; otherwise returns true.
See also isDesignable() and isStored().
bool QMetaProperty::isStored() const
Returns true if the property is stored; otherwise returns false.
The function returns false if the Q_PROPERTY()'s STORED attribute is false; otherwise returns true.
See also isDesignable() and isScriptable().
bool QMetaProperty::isUser() const
Returns false if the Q_PROPERTY()'s USER attribute is false. Otherwise it returns true, indicating the property is designated as the USER property, i.e., the one that the user can edit or that is significant in some other way.
See also QMetaObject::userProperty(), isDesignable(), and isScriptable().
bool QMetaProperty::isValid() const
Returns true if this property is valid (readable); otherwise returns false.
See also isReadable().
bool QMetaProperty::isWritable() const
Returns true if this property is writable; otherwise returns false.
See also isReadable() and write().
[since 6.0] QMetaType QMetaProperty::metaType() const
Returns this property's QMetaType.
This function was introduced in Qt 6.0.
See also QMetaType.
const char *QMetaProperty::name() const
Returns this property's name.
See also type() and typeName().
QMetaMethod QMetaProperty::notifySignal() const
Returns the QMetaMethod instance of the property change notifying signal if one was specified, otherwise returns an invalid QMetaMethod.
See also hasNotifySignal().
int QMetaProperty::notifySignalIndex() const
Returns the index of the property change notifying signal if one was specified, otherwise returns -1.
See also hasNotifySignal().
int QMetaProperty::propertyIndex() const
Returns this property's index.
QVariant QMetaProperty::read(const QObject *object) const
Reads the property's value from the given object. Returns the value if it was able to read it; otherwise returns an invalid variant.
See also write(), reset(), and isReadable().
QVariant QMetaProperty::readOnGadget(const void *gadget) const
Reads the property's value from the given gadget. Returns the value if it was able to read it; otherwise returns an invalid variant.
This function should only be used if this is a property of a Q_GADGET
int QMetaProperty::relativePropertyIndex() const
Returns this property's index relative within the enclosing meta object.
bool QMetaProperty::reset(QObject *object) const
Resets the property for the given object with a reset method. Returns true if the reset worked; otherwise returns false.
Reset methods are optional; only a few properties support them.
bool QMetaProperty::resetOnGadget(void *gadget) const
Resets the property for the given gadget with a reset method. Returns true if the reset worked; otherwise returns false.
Reset methods are optional; only a few properties support them.
This function should only be used if this is a property of a Q_GADGET
int QMetaProperty::revision() const
Returns the property revision if one was specified by Q_REVISION, otherwise returns 0. Since Qt 6.0, non-zero values are encoded and can be decoded using QTypeRevision::fromEncodedVersion().
[since 6.0] int QMetaProperty::typeId() const
Returns the storage type of the property. This is the same as metaType().id().
This function was introduced in Qt 6.0.
See also QMetaType, typeName(), and metaType().
const char *QMetaProperty::typeName() const
Returns the name of this property's type.
int QMetaProperty::userType() const
Returns this property's user type. The return value is one of the values that are registered with QMetaType.
This is equivalent to metaType().id()
See also type(), QMetaType, typeName(), and metaType().
bool QMetaProperty::write(QObject *object, const QVariant &value) const
Writes value as the property's value to the given object. Returns true if the write succeeded; otherwise returns false.
If value is not of the same type as the property, a conversion is attempted. An empty QVariant() is equivalent to a call to reset() if this property is resettable, or setting a default-constructed object otherwise.
Note: This function internally makes a copy of value. Prefer to use the rvalue overload when possible.
See also read(), reset(), and isWritable().
[since 6.6] bool QMetaProperty::write(QObject *object, QVariant &&v) const
This is an overloaded function.
This function was introduced in Qt 6.6.
bool QMetaProperty::writeOnGadget(void *gadget, const QVariant &value) const
Writes value as the property's value to the given gadget. Returns true if the write succeeded; otherwise returns false.
This function should only be used if this is a property of a Q_GADGET
[since 6.6] bool QMetaProperty::writeOnGadget(void *gadget, QVariant &&value) const
This is an overloaded function.
This function was introduced in Qt 6.6.