Struct mozjs::jsapi::JS::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(result.ok());
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 JS friend API and are defined in js/public/friend/ErrorNumbers.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.

Implementations

impl ObjectOpResult

pub fn ok(&self) -> bool

pub fn succeed(&mut self) -> bool

Set this ObjectOpResult to true and return true.

pub fn fail(&mut self, code: JSErrNum) -> bool

pub fn fail_cant_redefine_prop(&mut self) -> bool

pub fn fail_read_only(&mut self) -> bool

pub fn fail_getter_only(&mut self) -> bool

pub fn fail_cant_delete(&mut self) -> bool

pub fn fail_cant_set_interposed(&mut self) -> bool

pub fn fail_cant_define_window_element(&mut self) -> bool

pub fn fail_cant_delete_window_element(&mut self) -> bool

pub fn fail_cant_define_window_named_property(&mut self) -> bool

pub fn fail_cant_delete_window_named_property(&mut self) -> bool

pub fn fail_cant_define_window_non_configurable(&mut self) -> bool

pub fn fail_cant_prevent_extensions(&mut self) -> bool

pub fn fail_cant_set_proto(&mut self) -> bool

pub fn fail_no_named_setter(&mut self) -> bool

pub fn fail_no_indexed_setter(&mut self) -> bool

pub fn fail_not_data_descriptor(&mut self) -> bool

pub fn fail_invalid_descriptor(&mut self) -> bool

pub fn fail_bad_array_length(&mut self) -> bool

pub fn fail_bad_index(&mut self) -> bool

pub fn failure_code(&self) -> u32

pub fn failNoNamedSetter(&mut self) -> bool

👎Deprecated

Trait Implementations

impl Clone for ObjectOpResult

fn clone(&self) -> ObjectOpResult

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for ObjectOpResult

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for ObjectOpResult

fn default() -> ObjectOpResult

Returns the “default value” for a type.

impl PartialEq for ObjectOpResult

fn eq(&self, other: &ObjectOpResult) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for ObjectOpResult

impl StructuralPartialEq for ObjectOpResult