v8::Local< T > Class Template Reference

#include <v8.h>

Public Member Functions
template<class S >
V8_INLINE	Local (Local< S > that)
V8_INLINE bool	IsEmpty () const
V8_INLINE void	Clear ()
V8_INLINE T *	operator-> () const
V8_INLINE T *	operator* () const
template<class S >
V8_INLINE bool	operator== (const Local< S > &that) const
template<class S >
V8_INLINE bool	operator== (const PersistentBase< S > &that) const
template<class S >
V8_INLINE bool	operator!= (const Local< S > &that) const
template<class S >
V8_INLINE bool	operator!= (const Persistent< S > &that) const
template<class S >
V8_INLINE Local< S >	As () const

Static Public Member Functions
template<class S >
static V8_INLINE Local< T >	Cast (Local< S > that)
static V8_INLINE Local< T >	New (Isolate *isolate, Local< T > that)
static V8_INLINE Local< T >	New (Isolate *isolate, const PersistentBase< T > &that)

Friends
class	Utils
template<class F >
class	Eternal
template<class F >
class	PersistentBase
template<class F , class M >
class	Persistent
template<class F >
class	Local
template<class F >
class	MaybeLocal
template<class F >
class	FunctionCallbackInfo
template<class F >
class	PropertyCallbackInfo
class	String
class	Object
class	Context
class	Isolate
class	Private
template<class F >
class	internal::CustomArguments
class	HandleScope
class	EscapableHandleScope
template<class F1 , class F2 , class F3 >
class	PersistentValueMapBase
template<class F1 , class F2 >
class	PersistentValueVector
template<class F >
class	ReturnValue
Local< Primitive >	Undefined (Isolate *isolate)
Local< Primitive >	Null (Isolate *isolate)
Local< Boolean >	True (Isolate *isolate)
Local< Boolean >	False (Isolate *isolate)

Detailed Description

template<class T>
class v8::Local< T >

An object reference managed by the v8 garbage collector.

All objects returned from v8 have to be tracked by the garbage collector so that it knows that the objects are still alive. Also, because the garbage collector may move objects, it is unsafe to point directly to an object. Instead, all objects are stored in handles which are known by the garbage collector and updated whenever an object moves. Handles should always be passed by value (except in cases like out-parameters) and they should never be allocated on the heap.

There are two types of handles: local and persistent handles.

Local handles are light-weight and transient and typically used in local operations. They are managed by HandleScopes. That means that a HandleScope must exist on the stack when they are created and that they are only valid inside of the HandleScope active during their creation. For passing a local handle to an outer HandleScope, an EscapableHandleScope and its Escape() method must be used.

Persistent handles can be used when storing objects across several independent operations and have to be explicitly deallocated when they're no longer used.

It is safe to extract the object stored in the handle by dereferencing the handle (for instance, to extract the Object* from a Local<Object>); the value will still be governed by a handle behind the scenes and the same rules apply to these values as to their handles.

Constructor & Destructor Documentation

Local()

template<class T>

template<class S >

V8_INLINE v8::Local< T >::Local ( Local< S >  that )

inline

This check fails when trying to convert between incompatible handles. For example, converting from a Local<String> to a Local<Number>.

Member Function Documentation

As()

template<class T>

template<class S >

V8_INLINE Local<S> v8::Local< T >::As ( ) const

inline

Calling this is equivalent to Local<S>::Cast(). In particular, this is only valid if the handle actually refers to a value of the target type.

Cast()

template<class T>

template<class S >

static V8_INLINE Local<T> v8::Local< T >::Cast ( Local< S >  that )

inlinestatic

Cast a handle to a subclass, e.g. Local<Value> to Local<Object>. This is only valid if the handle actually refers to a value of the target type.

Clear()

template<class T>

V8_INLINE void v8::Local< T >::Clear ( )

inline

Sets the handle to be empty. IsEmpty() will then return true.

IsEmpty()

template<class T>

V8_INLINE bool v8::Local< T >::IsEmpty ( ) const

inline

Returns true if the handle is empty.

New()

template<class T>

Local< T > v8::Local< T >::New ( Isolate *  isolate, Local< T >  that  )

static

Create a local handle for the content of another handle. The referee is kept alive by the local handle even when the original handle is destroyed/disposed.

operator!=()

template<class T>

template<class S >

V8_INLINE bool v8::Local< T >::operator!= ( const Local< S > &  that ) const

inline

Checks whether two handles are different. Returns true if only one of the handles is empty, or if the objects to which they refer are different. The handles' references are not checked.

operator==()

template<class T>

template<class S >

V8_INLINE bool v8::Local< T >::operator== ( const Local< S > &  that ) const

inline

Checks whether two handles are the same. Returns true if both are empty, or if the objects to which they refer are identical. The handles' references are not checked.

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

• v8/include/v8.h