JS::Rooted 编辑

This article covers features introduced in SpiderMonkey 17

Local variable of type T whose value is always rooted.

Syntax

JS::Rooted<T> var(cx);
JS::Rooted<T> var(cx, initial);
JS::Rooted<T> var(rt);
JS::Rooted<T> var(rt, initial);

Methods

Here, ptr represents the private member of JS::Rooted<T>, typed with T.

Description

JS::Rooted<T> declares a local variable of type T whose value is always rooted. This is typically used for local variables, or for non-rooted values being passed to a function that requires a handle, e.g. Foo(JS::Rooted<T>(cx, x)).

JS::Rooted<T> may be automatically coerced to a JS::Handle<T>.  JS::Rooted<T> should be used whenever a local variable's value may be held live across a call which can trigger a GC.

If you want to add additional methods to Rooted for a specific specialization, define a js::RootedBase<T> specialization containing them.

There are typedefs available for the main types:

namespace JS {
typedef Rooted<JSObject*>       RootedObject;
typedef Rooted<JSFunction*>     RootedFunction;
typedef Rooted<JSScript*>       RootedScript;
typedef Rooted<JSString*>       RootedString;
typedef Rooted<JS::Symbol*>     RootedSymbol; // Added in SpiderMonkey 38
typedef Rooted<jsid>            RootedId;
typedef Rooted<JS::Value>       RootedValue;
}

See Also

• MXR ID Search for JS::Rooted
• MXR ID Search for JS::RootedObject
• MXR ID Search for JS::RootedFunction
• MXR ID Search for JS::RootedScript
• MXR ID Search for JS::RootedString
• MXR ID Search for JS::RootedSymbol
• MXR ID Search for JS::RootedId
• MXR ID Search for JS::RootedValue
• JS::Handle
• JS::MutableHandle
• GC Rooting Guide
• bug 756823
• bug 761391 - added JS::RootedScript
• bug 645416 - added JS::RootedSymbol