Can you expand on the benefits vs. costs (e.g., complexity, clarity)?
I ask because I'm not immediately seeing a lot of benefit, but I'm seeing
various costs:
1. It adds more hidden behavior (creating the object).
2. It makes object initializers more confusing to human readers. The
syntaxes `{"a.b": 42}` and `{[a.b]: 42}` are already both valid, and do
quite different things from each other; adding `{a.b: 42}` with yet a
third, different, behavior seems problematic (to me). The benefits of
computed property names were strong enough to justify the second syntax
above, but are the benefits of this sufficient for a third?
3. It adds complexity to object initializer processing, both in the obvious
way (has to figure out to create the hidden object or possibly several
nested hidden objects), and around the fact that object initializers are
processed in source code order.
Re that third point, consider this code using this new notation:
```js
const o = {
a.a: one(),
b: two(),
a.b: three()
};
```
Those functions should be called in the order `one`, `two`, `three`, which
means adding to the object on `a` later on in the initializer; it can't
just become:
```js
const o = {
a: { // WRONG
a: one(),
b: three()
},
b: two()
};
```
...because `three` would be called before `two`. I suppose the logic could
still be source code order, and the engine would break apart the
identifier, check to see if the first part already exists on the object and
use its value if so, add an object if not; rinse, repeat. If so, it raises
the question:
```js
const o = {
a: 1,
a.b: 42
};
```
Is that a syntax error? *(No, wait, it can't be; `1` could be any
expression.)* A runtime error? A silent runtime failure as `const o = {a:
1}; a.b = 42;` would be? Suppose we changed `a: 1` to `a: null`? `const o =
{a: null}; a.b = 42;` would throw, should this new syntax throw in that
case?
Weighed against those, the only real benefit I see is that it's *slightly*
more concise in the case of an object with a single property; but as of
even a second property, it's more verbose.
Sorry, this ran longer than I meant it to. Not trying to bash the idea,
these are just the things that jumped out at me and I type fairly quickly.
:-)
-- T.J. Crowder
On Thu, Jun 22, 2017 at 3:56 PM, Sebastian Malton <sebast...@malton.name>
wrote:
> I would like to propose that the dot or '.' is allowed in object field
> names so that the following are allowed.
>
> var obj = {
> field1: "val" ,
> field2.field3: 3,
> field2.field4: true
> };
>
> would become
> var obj = {
> field1: "val" ,
> field2: {
> field3: 3,
> field4: true
> }
> };
>
> and even
>
> var obj.name = "Hello" ;
>
> would become
>
> var obj = {
> name: "Hello"
> };
>
>
> Sebastian
>
>
> _______________________________________________
> es-discuss mailing list
> es-discuss@mozilla.org
> https://mail.mozilla.org/listinfo/es-discuss
>
>
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