V8
Public Member Functions | Static Public Member Functions | Friends | List of all members
v8::Handle< T > Class Template Reference

#include <v8.h>

Inheritance diagram for v8::Handle< T >:
v8::Local< T >

Public Member Functions

V8_INLINE Handle ()
template<class S >
V8_INLINE Handle (Handle< 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 Handle< S > &that) const
template<class S >
V8_INLINE bool operator== (const PersistentBase< S > &that) const
template<class S >
V8_INLINE bool operator!= (const Handle< S > &that) const
template<class S >
V8_INLINE bool operator!= (const Persistent< S > &that) const
template<class S >
V8_INLINE Handle< S > As ()

Static Public Member Functions

template<class S >
static V8_INLINE Handle< T > Cast (Handle< S > that)
static V8_INLINE Handle< T > New (Isolate *isolate, Handle< T > that)
static V8_INLINE Handle< T > New (Isolate *isolate, const PersistentBase< T > &that)

Friends

class Utils
class Persistent
class PersistentBase
class Handle
class Local
class FunctionCallbackInfo
class PropertyCallbackInfo
class internal::CustomArguments
class Context
class HandleScope
class Object
class Private
Handle< PrimitiveUndefined (Isolate *isolate)
Handle< PrimitiveNull (Isolate *isolate)
Handle< BooleanTrue (Isolate *isolate)
Handle< BooleanFalse (Isolate *isolate)

Detailed Description

template<class T>
class v8::Handle< 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. 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 Handle<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

template<class T>
V8_INLINE v8::Handle< T >::Handle ( )
inline

Creates an empty handle.

template<class T>
template<class S >
V8_INLINE v8::Handle< T >::Handle ( Handle< S >  that)
inline

Creates a handle for the contents of the specified handle. This constructor allows you to pass handles as arguments by value and to assign between handles. However, if you try to assign between incompatible handles, for instance from a Handle<String> to a Handle<Number> it will cause a compile-time error. Assigning between compatible handles, for instance assigning a Handle<String> to a variable declared as Handle<Value>, is legal because String is a subclass of Value.

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

Member Function Documentation

template<class T>
V8_INLINE void v8::Handle< T >::Clear ( )
inline

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

template<class T>
V8_INLINE bool v8::Handle< T >::IsEmpty ( ) const
inline

Returns true if the handle is empty.

Referenced by v8::PersistentBase< T >::Reset().

template<class T>
template<class S >
V8_INLINE bool v8::Handle< T >::operator!= ( const Handle< 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.

template<class T>
template<class S >
V8_INLINE bool v8::Handle< T >::operator== ( const Handle< 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.

Referenced by v8::Handle< Value >::operator!=().


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