On May 30, 2012, at 5:14 PM, Brendan Eich wrote:
> Allen Wirfs-Brock wrote:
>>
>> I now could be quite happy with the paren based cascade idea that Brendan
>> suggested last night. I'm surprised that no one has commented on the bnf I
>> provided in a subsequent message.
>
> Grammar is a detail at this point. The objection to parens is reasonable
> enough: they look bad when split across multiple lines:
>
> obj.(
> deep.(
> deeper: val;
> deeper2: val2
> )
> )
>
They look different, but it's not clear to me that it looks bad. I would use =
instead of : because we are really just factoring expressions and = is the
operator that we are dealing with.
There is a simple story for how:
obj.foo=val;
obj.bar=val2;
factors into:
obj.(
foo=val;
bar=val
);
or
obj.(foo=val, bar=val2);
changing the = to : seems arbitrarily different hurts the simple story. No
where else in the language does : mean assignment.
> (assume everything doesn't fit on one line).
>
> Schemers might style this thus:
>
> obj.(deep.(deeper: val;
> deeper2: val2))
>
> but that looks bad too -- too ragged-left with arbitrary indentation and ))))
> pile-ups at the end.
>
> Braces look right because they follow K&R style, which as Crock points out
> wins in JS because of restricted productions, specifically
K&S style can be applied whether you use () or {} so I don't see who that is
relevant.
>
> return {
> obj: literal,
> here: right
> };
>
> So,
>
> obj.{
> deep.{
> deeper: val;
> deeper2: val2
> }
> }
>
The big issue is the
obj .
{
deeper: val;
deeper2: val
}
look exactly like an object literal (except for the ; which is too small of a
difference to matter) but has different semantics.
Allen_______________________________________________
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