JSClassDefinition

#include <JavaScriptCore/JSObjectRef.h>

Overview

This structure contains properties and callbacks that define a type of object. All fields other than the version field are optional. Any pointer may be NULL.

• version The version number of this structure. The current version is 0.
• attributes A logically ORed set of JSClassAttributes to give to the class.
• className A null-terminated UTF8 string containing the class's name.
• parentClass A JSClass to set as the class's parent class. Pass NULL use the default object class.
• staticValues A JSStaticValue array containing the class's statically declared value properties. Pass NULL to specify no statically declared value properties. The array must be terminated by a JSStaticValue whose name field is NULL.
• staticFunctions A JSStaticFunction array containing the class's statically declared function properties. Pass NULL to specify no statically declared function properties. The array must be terminated by a JSStaticFunction whose name field is NULL.
• initialize The callback invoked when an object is first created. Use this callback to initialize the object.
• finalize The callback invoked when an object is finalized (prepared for garbage collection). Use this callback to release resources allocated for the object, and perform other cleanup.
• hasProperty The callback invoked when determining whether an object has a property. If this field is NULL, getProperty is called instead. The hasProperty callback enables optimization in cases where only a property's existence needs to be known, not its value, and computing its value is expensive.
• getProperty The callback invoked when getting a property's value.
• setProperty The callback invoked when setting a property's value.
• deleteProperty The callback invoked when deleting a property.
• getPropertyNames The callback invoked when collecting the names of an object's properties.
• callAsFunction The callback invoked when an object is called as a function.
• hasInstance The callback invoked when an object is used as the target of an 'instanceof' expression.
• callAsConstructor The callback invoked when an object is used as a constructor in a 'new' expression.
• convertToType The callback invoked when converting an object to a particular JavaScript type.

  Note

  The staticValues and staticFunctions arrays are the simplest and most efficient means for vending custom properties. Statically declared properties autmatically service requests like getProperty, setProperty, and getPropertyNames. Property access callbacks are required only to implement unusual properties, like array indexes, whose names are not known at compile-time.

  If you named your getter function "GetX" and your setter function "SetX", you would declare a JSStaticValue array containing "X" like this:

  JSStaticValue StaticValueArray[] = { { "X", GetX, SetX, kJSPropertyAttributeNone }, { 0, 0, 0, 0 } };

  Standard JavaScript practice calls for storing function objects in prototypes, so they can be shared. The default JSClass created by JSClassCreate follows this idiom, instantiating objects with a shared, automatically generating prototype containing the class's function objects. The kJSClassAttributeNoAutomaticPrototype attribute specifies that a JSClass should not automatically generate such a prototype. The resulting JSClass instantiates objects with the default object prototype, and gives each instance object its own copy of the class's function objects.

  A NULL callback specifies that the default object callback should substitute, except in the case of hasProperty, where it specifies that getProperty should substitute.

  It is not possible to use JS subclassing with objects created from a class definition that sets callAsConstructor by default. Subclassing is supported via the JSObjectMakeConstructor function, however.

Public Attributes
int	version
JSClassAttributes	attributes
const char *	className
JSClassRef	parentClass
const JSStaticValue *	staticValues
const JSStaticFunction *	staticFunctions
JSObjectInitializeCallback	initialize
JSObjectFinalizeCallback	finalize
JSObjectHasPropertyCallback	hasProperty
JSObjectGetPropertyCallback	getProperty
JSObjectSetPropertyCallback	setProperty
JSObjectDeletePropertyCallback	deleteProperty
JSObjectGetPropertyNamesCallback	getPropertyNames
JSObjectCallAsFunctionCallback	callAsFunction
JSObjectCallAsConstructorCallback	callAsConstructor
JSObjectHasInstanceCallback	hasInstance
JSObjectConvertToTypeCallback	convertToType

Member Data Documentation

attributes

JSClassAttributes attributes

callAsConstructor

JSObjectCallAsConstructorCallback callAsConstructor

callAsFunction

JSObjectCallAsFunctionCallback callAsFunction

className

const char* className

convertToType

JSObjectConvertToTypeCallback convertToType

deleteProperty

JSObjectDeletePropertyCallback deleteProperty

finalize

JSObjectFinalizeCallback finalize

getProperty

JSObjectGetPropertyCallback getProperty

getPropertyNames

JSObjectGetPropertyNamesCallback getPropertyNames

hasInstance

JSObjectHasInstanceCallback hasInstance

hasProperty

JSObjectHasPropertyCallback hasProperty

initialize

JSObjectInitializeCallback initialize

parentClass

JSClassRef parentClass

setProperty

JSObjectSetPropertyCallback setProperty

staticFunctions

const JSStaticFunction* staticFunctions

staticValues

const JSStaticValue* staticValues

version

int version

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The documentation for this struct was generated from the following file:

• JavaScriptCore/JSObjectRef.h