String(symbol)

Allen Wirfs-Brock allen at wirfs-brock.com
Wed Aug 13 10:11:53 PDT 2014


On Aug 13, 2014, at 8:45 AM, Nathan Wall wrote:

> Out of mere curiosity, why is it desired that `symbol + ''` throw?

Minimize the chance that somebody might code:
  var newName = somePropertyKey+"_stuff";
not realizing that somePropertyKey might be a Symbol.  We don't want to silently crete a string property name from a symbol.

Allen





> 
> Nathan
> 
> 
> 
> On Tue, Aug 12, 2014 at 10:39 PM, Erik Arvidsson <erik.arvidsson at gmail.com> wrote:
> symbol + '' must continue to throw.
> 
> I was suggesting that String(symbol) should not throw.
> 
> This can be spec'ed as String( value ) checking the Type of the value and special case it in case of the value being a symbol.
> 
> 
> On Tue, Aug 12, 2014 at 5:17 PM, Claude Pache <claude.pache at gmail.com> wrote:
> 
> Le 12 août 2014 à 22:35, Erik Arvidsson <erik.arvidsson at gmail.com> a écrit :
> 
>> Right now String(symbol) throws because it uses ToString which is spec'ed to throw.
>> 
>> I'm suggesting that we special case String(value) to do a type check for Symbol and return the same string as Symbol.prototype.toString.call(value) does.
>> 
>> https://people.mozilla.org/~jorendorff/es6-draft.html#sec-string-constructor-string-value
>> 
>> The motivation for this is that String(value) is pretty explicit and was in ES5 a safer way to stringify something than value.toString().
>> 
>> -- 
>> erik
> 
> +1. As I already noted last year [1], as currently specced, ad-hoc debugging code like `alert("got argument: " + x)` or `alert("got argument: " + String(x))` will throw for symbols, while `alert("got argument: " + x.toString())` will throw for `null`, `undefined`, and `Object.create(null)`.
> 
> [1] http://esdiscuss.org/topic/a-new-es6-draft-is-available#content-11
> 
> 
> 
> 
> 
> -- 
> erik
> 
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