QScriptClass Class

The QScriptClass class provides an interface for defining custom behavior of (a class of) Qt Script objects. 更多...

头：	#include <QScriptClass>
qmake:	QT += script
Since:	Qt 4.4

该类在 Qt 4.4 引入。

• 所有成员列表，包括继承成员

公共类型

enum	Extension { Callable, HasInstance }
enum	QueryFlag { HandlesReadAccess, HandlesWriteAccess }
flags	QueryFlags

公共函数

	QScriptClass (QScriptEngine * engine )
virtual	~QScriptClass ()
QScriptEngine *	engine () const
virtual QVariant	extension (QScriptClass::Extension extension , const QVariant & argument = QVariant())
virtual QString	name () const
virtual QScriptClassPropertyIterator *	newIterator (const QScriptValue & object )
virtual QScriptValue	property (const QScriptValue & object , const QScriptString & name , uint id )
virtual QScriptValue::PropertyFlags	propertyFlags (const QScriptValue & object , const QScriptString & name , uint id )
virtual QScriptValue	prototype () const
virtual QScriptClass::QueryFlags	queryProperty (const QScriptValue & object , const QScriptString & name , QScriptClass::QueryFlags flags , uint * id )
virtual void	setProperty (QScriptValue & object , const QScriptString & name , uint id , const QScriptValue & value )
virtual bool	supportsExtension (QScriptClass::Extension extension ) const

详细描述

The QScriptClass class defines an interface for handling various aspects of interaction with the Qt Script objects associated with the class. Such objects are created by calling QScriptEngine::newObject (), passing a pointer to the QScriptClass as argument.

By subclassing QScriptClass, you can define precisely how access to properties of the objects that use your class is handled. This enables a fully dynamic handling of properties, e.g. it's more powerful than QScriptEngine::newQObject (). For example, you can use QScriptClass to implement array-type objects (i.e. objects that handle the length property, and properties whose names are valid array indexes, in a special way), or to implement a "live" (runtime-defined) proxy to an underlying object.

If you just need to handle access to a set of properties that are known at the time an object is created (i.e. "semi-statically"), you might consider using QScriptValue::setProperty () to define getter/setter functions for the relevant properties, rather than subclassing QScriptClass.

重实现 queryProperty () to specify which properties are handled in a custom way by your script class (i.e. should be delegated to the QScriptClass), and which properties should be handled just like normal Qt Script object properties.

重实现 property () 和 setProperty () to perform the actual access (read or write) to the properties that your class handles. Additionally, you can reimplement propertyFlags () to specify custom flags for your properties.

重实现 newIterator () to provide an iterator for objects of your custom class. This is only necessary if objects of your class can have custom properties that you want to be reported when an object is used together with the QScriptValueIterator class, or when an object is used in a for-in enumeration statement in a script.

When implementing custom classes of objects, you typically use QScriptValue::setData () to store instance-specific data as part of object initialization; the data won't be accessible from scripts directly, but you can access it in e.g. your reimplementations of property () 和 setProperty () (by calling QScriptValue::data ()) to perform custom processing.

重实现 prototype () to provide a custom prototype object for your script class.

重实现 supportsExtension () 和 extension () if your custom script class supports one or more of the extensions specified by the Extension enum.

另请参阅 QScriptClassPropertyIterator , QScriptEngine::newObject ()，和 Defining Custom Script Classes with QScriptClass .

成员类型文档编制

enum QScriptClass:: Extension

This enum specifies the possible extensions to a QScriptClass .

常量	值	描述
QScriptClass::Callable	0	Instances of this class can be called as functions.
QScriptClass::HasInstance	1	Instances of this class implement [[HasInstance]].

另请参阅 extension ().

enum QScriptClass:: QueryFlag
flags QScriptClass:: QueryFlags

This enum describes flags that are used to query a QScriptClass regarding how access to a property should be handled.

常量	值	描述
QScriptClass::HandlesReadAccess	0x01	The QScriptClass handles read access to this property.
QScriptClass::HandlesWriteAccess	0x02	The QScriptClass handles write access to this property.

The QueryFlags type is a typedef for QFlags <QueryFlag>. It stores an OR combination of QueryFlag values.

另请参阅 queryProperty ().

成员函数文档编制

QScriptClass:: QScriptClass ( QScriptEngine * engine )

Constructs a QScriptClass object to be used in the given engine .

The engine does not take ownership of the QScriptClass object.

[虚拟] QScriptClass:: ~QScriptClass ()

销毁 QScriptClass 对象。

若 QScriptClass object is deleted before the associated engine (), any Qt Script objects using the QScriptClass will be "demoted" to normal Qt Script objects.

QScriptEngine *QScriptClass:: engine () const

Returns the engine that this QScriptClass is associated with.

[虚拟] QVariant QScriptClass:: extension ( QScriptClass::Extension extension , const QVariant & argument = QVariant())

This virtual function can be reimplemented in a QScriptClass subclass to provide support for extensions. The optional argument can be provided as input to the extension ; the result must be returned in the form of a QVariant 。可以调用 supportsExtension () to check if an extension is supported by the QScriptClass . By default, no extensions are supported, and this function returns an invalid QVariant .

If you implement the Callable extension, Qt Script will call this function when an instance of your class is called as a function (e.g. from a script or using QScriptValue::call ())。 argument will contain a pointer to the QScriptContext that represents the function call, and you should return a QVariant that holds the result of the function call. In the following example the sum of the arguments to the script function are added up and returned:

if (extension == Callable) {
    QScriptContext *context = qvariant_cast<QScriptContext*>(argument);
    QScriptEngine *engine = context->engine();
    double sum = 0;
    for (int i = 0; i < context->argumentCount(); ++i)
        sum += context->argument(i).toNumber();
    return sum;
}
					

If you implement the HasInstance extension, Qt Script will call this function as part of evaluating the instanceof operator, as described in ECMA-262 Section 11.8.6. The argument is a QScriptValueList containing two items: The first item is the object that HasInstance is being applied to (an instance of your class), and the second item can be any value. extension() should return true if the value delegates behavior to the object, false otherwise.

另请参阅 supportsExtension ().

[虚拟] QString QScriptClass:: name () const

Returns the name of the script class.

Qt Script uses this name to generate a default string representation of objects in case you do not provide a toString function.

The default implementation returns a null string.

[虚拟] QScriptClassPropertyIterator *QScriptClass:: newIterator (const QScriptValue & object )

Returns an iterator for traversing custom properties of the given object .

The default implementation returns 0, meaning that there are no custom properties to traverse.

Reimplement this function if objects of your script class can have one or more custom properties (e.g. those reported to be handled by queryProperty ()) that you want to appear when an object's properties are enumerated (e.g. by a for-in statement in a script).

Qt Script takes ownership of the new iterator object.

另请参阅 QScriptValueIterator .

[虚拟] QScriptValue QScriptClass:: property (const QScriptValue & object , const QScriptString & name , uint id )

Returns the value of the property with the given name 为给定 object .

The id argument is only useful if you assigned a value to it in queryProperty ().

The default implementation does nothing and returns an invalid QScriptValue .

另请参阅 setProperty () 和 propertyFlags ().

[虚拟] QScriptValue::PropertyFlags QScriptClass:: propertyFlags (const QScriptValue & object , const QScriptString & name , uint id )

Returns the flags of the property with the given name 为给定 object .

The id argument is only useful if you assigned a value to it in queryProperty ().

The default implementation returns 0.

另请参阅 property ().

[虚拟] QScriptValue QScriptClass:: prototype () const

Returns the object to be used as the prototype of new instances of this class (created with QScriptEngine::newObject ()).

The default implementation returns an invalid QScriptValue , meaning that the standard Object prototype will be used. Reimplement this function to provide your own custom prototype.

Typically you initialize your prototype object in the constructor of your class, then return it in this function.

See the "Making Use of Prototype-Based Inheritance" section in the Qt Script documentation for more information on how prototypes are used.

[虚拟] QScriptClass::QueryFlags QScriptClass:: queryProperty (const QScriptValue & object , const QScriptString & name , QScriptClass::QueryFlags flags , uint * id )

Queries this script class for how access to the property with the given name 为给定 object should be handled. The given flags specify the aspects of interest. This function should return a subset of flags to indicate which aspects of property access should be further handled by the script class.

For example, if the flags contain HandlesReadAccess , and you would like your class to handle the reading of the property (through the property () function), the returned flags should include HandlesReadAccess . If the returned flags do not contain HandlesReadAccess , the property will be handled as a normal script object property.

You can optionally use the id argument to store a value that will subsequently be passed on to functions such as property () 和 setProperty ().

The default implementation of this function returns 0.

Note: This function is only called if the given property isn't already a normal property of the object. For example, say you advertise that you want to handle read access to property foo , but not write access; if foo is then assigned a value, it will become a normal script object property, and subsequently you will no longer be queried regarding read access to foo .

另请参阅 property ().

[虚拟] void QScriptClass:: setProperty ( QScriptValue & object , const QScriptString & name , uint id , const QScriptValue & value )

Sets the property with the given name 为给定 object 到给定 value .

The id argument is only useful if you assigned a value to it in queryProperty ().

默认实现什么都不做。

An invalid value represents a request to remove the property.

另请参阅 property ().

[虚拟] bool QScriptClass:: supportsExtension ( QScriptClass::Extension extension ) const

返回 true 若 QScriptClass supports the given extension ; otherwise, false is returned. By default, no extensions are supported.

Reimplement this function to indicate which extensions your custom class supports.

另请参阅 extension ().

内容

• 公共类型

• 公共函数

• 详细描述