Struct js::jsapi::ObjectOpResult

#[repr(C)]
pub struct ObjectOpResult {
    pub code_: usize,
}

Per ES6, the [[DefineOwnProperty]] internal method has three different possible outcomes:

• It can throw an exception (which we indicate by returning false).

• It can return true, indicating unvarnished success.

• It can return false, indicating "strict failure". The property could not be defined. It's an error, but no exception was thrown.

It's not just [[DefineOwnProperty]]: all the mutating internal methods have the same three outcomes. (The other affected internal methods are [[Set]], [[Delete]], [[SetPrototypeOf]], and [[PreventExtensions]].)

If you think this design is awful, you're not alone. But as it's the standard, we must represent these boolean "success" values somehow. ObjectOpSuccess is the class for this. It's like a bool, but when it's false it also stores an error code.

Typical usage:

ObjectOpResult result;
if (!DefineProperty(cx, obj, id, ..., result))
    return false;
if (!result)
    return result.reportError(cx, obj, id);

Users don't have to call result.report(); another possible ending is:

argv.rval().setBoolean(bool(result));
return true;

Fields

code_: usize

code_ is either one of the special codes OkCode or Uninitialized, or an error code. For now the error codes are private to the JS engine; they're defined in js/src/js.msg.

code_ is uintptr_t (rather than uint32_t) for the convenience of the JITs, which would otherwise have to deal with either padding or stack alignment on 64-bit platforms.

Methods

impl ObjectOpResult

pub unsafe fn failCantRedefineProp(&mut self) -> bool

pub unsafe fn failReadOnly(&mut self) -> bool

pub unsafe fn failGetterOnly(&mut self) -> bool

pub unsafe fn failCantDelete(&mut self) -> bool

pub unsafe fn failCantSetInterposed(&mut self) -> bool

pub unsafe fn failCantDefineWindowElement(&mut self) -> bool

pub unsafe fn failCantDeleteWindowElement(&mut self) -> bool

pub unsafe fn failCantDeleteWindowNamedProperty(&mut self) -> bool

pub unsafe fn failCantPreventExtensions(&mut self) -> bool

pub unsafe fn failCantSetProto(&mut self) -> bool

pub unsafe fn failNoNamedSetter(&mut self) -> bool

pub unsafe fn failNoIndexedSetter(&mut self) -> bool

pub unsafe fn reportStrictErrorOrWarning(
    &mut self,
    cx: *mut JSContext,
    obj: HandleObject,
    id: HandleId,
    strict: bool
) -> bool

pub unsafe fn reportStrictErrorOrWarning1(
    &mut self,
    cx: *mut JSContext,
    obj: HandleObject,
    strict: bool
) -> bool

impl ObjectOpResult

pub fn succeed(&mut self) -> bool

Set this ObjectOpResult to true and return true.

Trait Implementations

impl Debug for ObjectOpResult

fn fmt(&self, __arg_0: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Copy for ObjectOpResult

impl Clone for ObjectOpResult

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.