JSAutoCompartment 编辑

This article covers features introduced in SpiderMonkey 24

RAII helper to enter a different compartment on the given context and automatically leave it once the JSAutoCompartment instance gets out of scope.

Syntax

JSAutoCompartment(JSContext *cx, JSObject *target);

JSAutoCompartment(JSContext *cx, JSScript *target);

Name	Type	Description
cx	JSContext *	The context on which a cross-compartment call is needed.
target	JSObject * / JSScript *	The object in a different compartment to be accessed. This implicitly identifies the compartment to be entered.

Description

Every JSContext has a current compartment. Only objects in the current compartment can be accessed, so to access an object in a different compartment, this containing compartment has to be entered first. Compartments have to be entered and left in LIFO order. JSAutoCompartment guarantees that by automatically entering the given compartment and leaving it upon getting out of scope:

void foo(JSContext *cx, JObject *obj) {
    // in some compartment 'c'
    {
        JSAutoCompartment ac(cx, obj);  // constructor enters
        // in the compartment of 'obj'
    }                                 // destructor leaves
    // back in compartment 'c'
}

See Also

• MXR ID Search for JSAutoCompartment
• bug 860050
• bug 833817
• bug 786068