On Nov 5, 2011, at 5:52 PM, Allen Wirfs-Brock wrote:
> On Nov 5, 2011, at 2:34 PM, Brendan Eich wrote:
>
>> On Nov 5, 2011, at 11:27 AM, Allen Wirfs-Brock wrote:
>>
It should, as no length is assumed to mean "length === 0", IIUC, and
that seems so unintuitive to me that it sways my opi
On Nov 5, 2011, at 5:40 PM, Allen Wirfs-Brock wrote:
> In general, destructuring already has too many moving parts to simply be a
> simple desugaring. array/object distinctions, rests on the LHS, default
> value specifiers, etc. I'm specifying it like any other feature in the
> language.
Tak
On Nov 5, 2011, at 3:50 PM, Erik Arvidsson wrote:
> On Sat, Nov 5, 2011 at 14:41, Brendan Eich wrote:
>> 1. Should an array pattern always query 'length'?
>>
>> 2. If the answer to (1) is "no", then should ... in an array pattern query
>> 'length'?
>>
>> On reflection and at this point in the
On Nov 5, 2011, at 2:34 PM, Brendan Eich wrote:
> On Nov 5, 2011, at 11:27 AM, Allen Wirfs-Brock wrote:
>
>>> It should, as no length is assumed to mean "length === 0", IIUC, and
>>> that seems so unintuitive to me that it sways my opinion towards not
>>> imposing array-ness on the RHS.
>>
>> b
On Nov 5, 2011, at 2:28 PM, Brendan Eich wrote:
> On Nov 5, 2011, at 10:24 AM, Allen Wirfs-Brock wrote:
>
>> On Nov 5, 2011, at 9:59 AM, John J Barton wrote:
>>
>>> ...
>>>
>>> I don't understand what " the source object is only has two
>>> "array-like" elements" can mean.
>>
>>
>> If you us
On Nov 5, 2011, at 12:38 PM, Erik Arvidsson wrote:
> On Sat, Nov 5, 2011 at 11:55, Brendan Eich wrote:
>> The issue with ... in an array destructuring pattern is different from the
>> case without. We have a choice, as you say. It's not obvious that doing a
>> "get" of 'length' on the RHS (onc
On Sat, Nov 5, 2011 at 14:41, Brendan Eich wrote:
> 1. Should an array pattern always query 'length'?
>
> 2. If the answer to (1) is "no", then should ... in an array pattern query
> 'length'?
>
> On reflection and at this point in the thread, with your reply in mind, my
> prefs in order: [no, y
On Nov 5, 2011, at 12:38 PM, Erik Arvidsson wrote:
> On Sat, Nov 5, 2011 at 11:55, Brendan Eich wrote:
>> The issue with ... in an array destructuring pattern is different from the
>> case without. We have a choice, as you say. It's not obvious that doing a
>> "get" of 'length' on the RHS (once
On Nov 5, 2011, at 11:27 AM, Allen Wirfs-Brock wrote:
>> It should, as no length is assumed to mean "length === 0", IIUC, and
>> that seems so unintuitive to me that it sways my opinion towards not
>> imposing array-ness on the RHS.
>
> but that is exactly how it works everywhere else length is u
On Nov 5, 2011, at 11:01 AM, John J Barton wrote:
> I can see why my version is wrong
Your interpretion is not wrong.
> But the feature does not do this. Rather, since LHS is array, it
> coerces the RHS to an array:
> let z = coerceToArray(_rhs)[0];
> and we don't know what that operation mean
On Nov 5, 2011, at 10:24 AM, Allen Wirfs-Brock wrote:
> On Nov 5, 2011, at 9:59 AM, John J Barton wrote:
>
>> (Oh great more features that turn programming into little brain teasers :-( )
>>
>> Devs need an algorithm:
>>
>> let _lhs = [];
>> let _rhs = {0:0, 1:1, length: 2, 2:2};
>> _lhs[0] =
On Sat, Nov 5, 2011 at 11:55, Brendan Eich wrote:
> The issue with ... in an array destructuring pattern is different from the
> case without. We have a choice, as you say. It's not obvious that doing a
> "get" of 'length' on the RHS (once per ...) is the right answer. It's
> plausible in my vi
On Nov 5, 2011, at 9:38 AM, Allen Wirfs-Brock wrote:
> In a similar vain, what is the value of r in:
>
> let [z,y,...r] = {0:0, 1:1, 2:2, length: 3, 3:3,4:4};
>
> should it be [2] or [2,3,4] (and if the latter how is that determined)?
The inspiration for ... in the past came from (among other
On Sat, Nov 5, 2011 at 19:27, Allen Wirfs-Brock wrote:
>>> ToInteger( obj.[[Get]]("length"))
>>> evaluates to 0 if length is missing or has a bogus value.
>>
>> So in your favored solution, would the following example result in x,
>> y, and z all being undefined?
>> let [x,y,z] = {0:0, 1:1, 2:2
On Nov 5, 2011, at 9:59 AM, John J Barton wrote:
> On Sat, Nov 5, 2011 at 9:28 AM, Allen Wirfs-Brock
> wrote:
>> In the following declaration, what should be the value of z?
>>
>> let [z,y,z] = {0:0, 1:1, length: 2, 2:2};
>>
>> should it be be 2 or undefined
>>
>> undefined might be reasonabl
On Nov 5, 2011, at 11:11 AM, Till Schneidereit wrote:
> On Sat, Nov 5, 2011 at 18:10, Allen Wirfs-Brock wrote:
>>
>>> What if the RHS doesn't have a length property at all? Or it has one
>>> with a value that isn't convertible to a number? No need for that
>>> complexity.
>>
>> This case is co
On Nov 5, 2011, at 11:01 AM, John J Barton wrote:
>>
>
> I can see why my version is wrong: I am interpreting square brackets
> on the RHS like JS devs would.
> let z = _rhs[0]; // LHS was array, so get zeroth elt,but RHS is
> object so property access.
>
> But the feature does not do this. Ra
On Nov 5, 2011, at 10:57 AM, Claus Reinke wrote:
>> In the following declaration, what should be the value of z?
>> let [z,y,z] = {0:0, 1:1, length: 2, 2:2};
>
> and there I was, thinking I understood more than half of JS..
>
> Since this was new to me, I referred to the spec. Here is my
> rea
On Sat, Nov 5, 2011 at 18:10, Allen Wirfs-Brock wrote:
>
>> What if the RHS doesn't have a length property at all? Or it has one
>> with a value that isn't convertible to a number? No need for that
>> complexity.
>
> This case is consistently handled throughtout the ES spec:
> ToInteger( obj.[[
On Sat, Nov 5, 2011 at 10:24 AM, Allen Wirfs-Brock
wrote:
>
> On Nov 5, 2011, at 9:59 AM, John J Barton wrote:
>
>>>
>>
>> (Oh great more features that turn programming into little brain teasers :-( )
>>
>> Devs need an algorithm:
>>
>> let _lhs = [];
>> let _rhs = {0:0, 1:1, length: 2, 2:2};
>>
In the following declaration, what should be the value of z?
let [z,y,z] = {0:0, 1:1, length: 2, 2:2};
and there I was, thinking I understood more than half of JS..
Since this was new to me, I referred to the spec. Here
is my reading are my readings:
The rhs is an Object, but not an Array -
On Nov 5, 2011, at 9:59 AM, John J Barton wrote:
>>
>
> (Oh great more features that turn programming into little brain teasers :-( )
>
> Devs need an algorithm:
>
> let _lhs = [];
> let _rhs = {0:0, 1:1, length: 2, 2:2};
> _lhs[0] = _rhs[0];
> _lhs[1] = _rhs[1];
> _lhs[2] = _rhs[2];
> let z
On Nov 5, 2011, at 10:04 AM, Dmitry Soshnikov wrote:
> On 05.11.2011 20:54, Allen Wirfs-Brock wrote:
>> On Nov 5, 2011, at 9:45 AM, Dmitry Soshnikov wrote:
>>
>>> On 05.11.2011 20:38, Allen Wirfs-Brock wrote:
In a similar vain, what is the value of r in:
let [z,y,...r] = {0:0, 1:
On Nov 5, 2011, at 9:59 AM, Lasse Reichstein wrote:
> On Sat, Nov 5, 2011 at 5:28 PM, Allen Wirfs-Brock
> wrote:
>> In the following declaration, what should be the value of z?
>>
>> let [z,y,z] = {0:0, 1:1, length: 2, 2:2};
>
> (I assume the pattern should be [x,y,z], not [z,y,z], or am I mi
On 05.11.2011 21:04, Dmitry Soshnikov wrote:
On 05.11.2011 20:54, Allen Wirfs-Brock wrote:
On Nov 5, 2011, at 9:45 AM, Dmitry Soshnikov wrote:
On 05.11.2011 20:38, Allen Wirfs-Brock wrote:
In a similar vain, what is the value of r in:
let [z,y,...r] = {0:0, 1:1, 2:2, length: 3, 3:3,4:4};
sh
On 05.11.2011 20:54, Allen Wirfs-Brock wrote:
On Nov 5, 2011, at 9:45 AM, Dmitry Soshnikov wrote:
On 05.11.2011 20:38, Allen Wirfs-Brock wrote:
In a similar vain, what is the value of r in:
let [z,y,...r] = {0:0, 1:1, 2:2, length: 3, 3:3,4:4};
should it be [2] or [2,3,4] (and if the latter
On 05.11.2011 20:49, Allen Wirfs-Brock wrote:
On Nov 5, 2011, at 9:38 AM, Dmitry Soshnikov wrote:
On 05.11.2011 20:28, Allen Wirfs-Brock wrote:
In the following declaration, what should be the value of z?
let [z,y,z] = {0:0, 1:1, length: 2, 2:2};
should it be be 2 or undefined
undefined mig
On Sat, Nov 5, 2011 at 5:28 PM, Allen Wirfs-Brock wrote:
> In the following declaration, what should be the value of z?
>
> let [z,y,z] = {0:0, 1:1, length: 2, 2:2};
(I assume the pattern should be [x,y,z], not [z,y,z], or am I missing a point?)
> should it be be 2 or undefined
If it does anyth
On Sat, Nov 5, 2011 at 9:28 AM, Allen Wirfs-Brock wrote:
> In the following declaration, what should be the value of z?
>
> let [z,y,z] = {0:0, 1:1, length: 2, 2:2};
>
> should it be be 2 or undefined
>
> undefined might be reasonable because it is an array pattern, and the source
> object is onl
To me the lhs indicates: array. Thus, the rhs is a pseudo-array. When used as
such we get:
> [].join.call({0:0, 1:1, length: 2, 2:2}, "-")
'0-1'
Thus, 2 is invisible. That’s what I would expect, too, intuitively. I’d think
that the assignment should reflect that (thus: z = undefined)
On
On Nov 5, 2011, at 9:44 AM, Brendan Eich wrote:
> On Nov 5, 2011, at 9:28 AM, Allen Wirfs-Brock wrote:
>
>> In the following declaration, what should be the value of z?
>>
>> let [z,y,z] = {0:0, 1:1, length: 2, 2:2};
>>
>> should it be be 2 or undefined
>>
>> undefined might be reasonable bec
On Nov 5, 2011, at 9:45 AM, Dmitry Soshnikov wrote:
> On 05.11.2011 20:38, Allen Wirfs-Brock wrote:
>> In a similar vain, what is the value of r in:
>>
>> let [z,y,...r] = {0:0, 1:1, 2:2, length: 3, 3:3,4:4};
>>
>> should it be [2] or [2,3,4] (and if the latter how is that determined)?
>>
>>
On Nov 5, 2011, at 9:38 AM, Dmitry Soshnikov wrote:
> On 05.11.2011 20:28, Allen Wirfs-Brock wrote:
>> In the following declaration, what should be the value of z?
>>
>> let [z,y,z] = {0:0, 1:1, length: 2, 2:2};
>>
>> should it be be 2 or undefined
>>
>> undefined might be reasonable because i
On 05.11.2011 20:38, Allen Wirfs-Brock wrote:
In a similar vain, what is the value of r in:
let [z,y,...r] = {0:0, 1:1, 2:2, length: 3, 3:3,4:4};
should it be [2] or [2,3,4] (and if the latter how is that determined)?
It seems to me that [2] is the right answer,
How so? If `...n` is the ran
On Nov 5, 2011, at 9:28 AM, Allen Wirfs-Brock wrote:
> In the following declaration, what should be the value of z?
>
> let [z,y,z] = {0:0, 1:1, length: 2, 2:2};
>
> should it be be 2 or undefined
>
> undefined might be reasonable because it is an array pattern, and the source
> object is only
On 05.11.2011 20:28, Allen Wirfs-Brock wrote:
In the following declaration, what should be the value of z?
let [z,y,z] = {0:0, 1:1, length: 2, 2:2};
should it be be 2 or undefined
undefined might be reasonable because it is an array pattern, and the source object is
only has two "array-like"
In a similar vain, what is the value of r in:
let [z,y,...r] = {0:0, 1:1, 2:2, length: 3, 3:3,4:4};
should it be [2] or [2,3,4] (and if the latter how is that determined)?
It seems to me that [2] is the right answer, and if that is the cause,
consistency requires that for the first problem z g
In the following declaration, what should be the value of z?
let [z,y,z] = {0:0, 1:1, length: 2, 2:2};
should it be be 2 or undefined
undefined might be reasonable because it is an array pattern, and the source
object is only has two "array-like" elements
2 might be reasonable because the sourc
If only we could use any Unicode character, then <| might look like:
◀
but this is more symbolic of what is actually going on:
⥆
of course if we are talking about classes with parallel inheritance hierarchies
it might be better to use:
⇇
And who could resisting trying to make one
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