On Tue, Dec 2, 2014 at 9:56 AM, Andrea Giammarchi <
[email protected]> wrote:
> I think by `@@toStringTag` he meant the ability to define a `[[Class]]`
> name so that `{}.toString.call(generic)` would return such name instead of
> `Object` but I'm sure Dmitry will come back explaining and/or asking more.
>
Yeah, so basically current `O.p.toString` [1] in step 14 delegates to the
`@@toStringTag`. Which means user-classes have ability to ad-hoc the result
of using _default_ `toString` from `O.p`.
In a class users have to put it manually at the moment:
```
class Point {
constructor(x, y) {
this._x = x;
this._y = y;
}
toString() {
return '<Point ' + this._x + ', ' + this._y + '>';
}
[Symbol.toStringTag]() {
return 'Point';
}
}
var p = new Point(10, 20);
console.log(p.toString()); // '<Point 10, 20>'
console.log(({}).toString.call(p)); // '[object Point]'
```
Notice how the implementation defines its own `toString`, and at the same
time provides the ability to test the type tag with the `O.p.toString`.
So my proposal is to provide default implicit implementation of that
`Symbol.toStringTag` method (which is `@@toStringTag` in the spec).
Dmitry
[1]
https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.prototype.tostring
>
> On Tue, Dec 2, 2014 at 4:49 PM, Claude Pache <[email protected]>
> wrote:
>
>>
>> > Le 2 déc. 2014 à 08:46, Dmitry Soshnikov <[email protected]>
>> a écrit :
>> >
>> > Hi,
>> >
>> > Probably worth providing a default implementation of the
>> `@@toStringTag` when evaluating a class [1]. In this case users will be
>> able to do:
>> >
>> > ```
>> > class Point { ... }
>> >
>> > var p = new Point(1, 2);
>> > console.log(p); // "[object Point]"
>> > ```
>>
>> You seem to imply that `console.log(p)` will show the result of
>> `p.toString()` in the console. But it is not the case for the majority of
>> browsers.
>>
>> I've just tried:
>>
>> ```
>> var Point = function() {}
>> Point.prototype.toString = function() { return "(this is an object of
>> type Point)" }
>> console.log(new Point)
>> ```
>>
>> Results are:
>>
>> Firefox: Object { }
>> Chrome: Point{toString: function}
>> Safari: Object
>> IE: [object Object] (this is an object of type Point)
>>
>> In particular, note that Chrome doesn't need the help of `.toString()` in
>> order to log useful information.
>>
>> —Claude
>> _______________________________________________
>> es-discuss mailing list
>> [email protected]
>> https://mail.mozilla.org/listinfo/es-discuss
>>
>
>
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
