I see. That's unpleasant. In ES5, Object(x) can never throw, and so the
code paths using |x === Object(x)| are not prepared for a throw. Much old
code will break.


On Mon, Jul 15, 2013 at 8:01 AM, Jeremy Martin <jmar777 at gmail.com> wrote:

> > s === Object(s)
>
> This should throw a TypeError.  In the case of a Symbol, `Object(*value*)`
> results in `ToObject(*value*)` [1].  And, in the case of Symbol, ToObject
> should throw a TypeError [2].
>
> [1] http://people.mozilla.org/~jorendorff/es6-draft.html#sec-15.2.1.1
> [2] http://people.mozilla.org/~jorendorff/es6-draft.html#sec-9.1.9
>
> On Mon, Jul 15, 2013 at 10:48 AM, Mark S. Miller <erights at google.com>wrote:
>
>> Given that s is a Symbol and b is a Bignum, is
>>
>>     s === Object(s)
>>
>> ?
>>
>> Is
>>
>>     b === Object(b)
>>
>>  ?
>>
>> The reason I ask is that x === Object(x) is often used to distinguish
>> primitive values from objects. The other thing that's often used is typeof,
>> but these uses of typeof usually assume that the full range of possible
>> answers is already known. If we're going to be expanding the typeof
>> answers, then we need guidance on how to write this test now (es5) such
>> that it stays robust.
>>
>>
>> --
>>     Cheers,
>>     --MarkM
>>
>> _______________________________________________
>> es-discuss mailing list
>> es-discuss at mozilla.org
>> https://mail.mozilla.org/listinfo/es-discuss
>>
>>
>
>
> --
> Jeremy Martin
> 661.312.3853
> http://devsmash.com
> @jmar777
>



-- 
    Cheers,
    --MarkM
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I see. That's unpleasant. In ES5, `Object(x)` can never throw, and so the
code paths using `x === Object(x)` are not prepared for a throw. Much old
code will break.