Object.is steps are very thing

Allen Wirfs-Brock allen at wirfs-brock.com
Sat Mar 16 16:56:30 PDT 2013


On Mar 16, 2013, at 4:42 PM, Tom Schuster wrote:

> I would argue that the disclaimer makes this more confusing. I am
> aware of the behavior that not passed parameters are undefined. But It
> sounded like we would never execute step 1. when the parameter count
> doesn't match. And thus leaving the result of the call not defined.

I see...it certainly isn't intended for those preambles to be interpreted in that way.  They really are just boiler plate for inducing the the italic parameter names.

If there is an actual overload based upon the number of passed arguments we are much more explict.   See for example, 15.4.1.1 and 15.4.1.2.

Nobody had previously brought this particular point of confusion to may attention.  It should like I shold change the standard boiler plate preamble to something slike:

The *is* function takes parameters /value1/ and /value2/ and performs the following steps when called:

Allen



> 
> On Sun, Mar 17, 2013 at 12:06 AM, Allen Wirfs-Brock
> <allen at wirfs-brock.com> wrote:
>> 
>> On Mar 16, 2013, at 3:40 PM, David Bruant wrote:
>> 
>>> Le 16/03/2013 19:18, Tom Schuster a écrit :
>>>> Hey!
>>>> 
>>>> Looking at the the steps for Object.is the first sentence just says:
>>>>> "When the is function is called with arguments value1 and value2 the following steps are taken:"
>>>> I don't remember other functions being defined like that. It should at
>>>> least say something along the lines of
>>>> "When called with less than 2 parameters return false."
>>> I'd throw a TypeError. Calling Object.is with strictly more or less than 2 parameters is most likely an error, akin to === with which something different than strictly 2 operands resultsis a SyntaxError.
>> 
>> 
>> ECMAScript has a well established convention of using undefined for any non-supplied argument values.  It's preferable to consistently follow such conventions.
>> 
>> Allen
>> 
>> 
>> 
>> 
>> 
> 



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