On 2014/06/26 15:55:12, rossberg wrote:
On 2014/06/25 16:08:37, wingo wrote:
> PTAL; an early RFC patch for comments. Some more tests are needed for
> accessor/data duplicate property interactions. I propose not doing this
change
> behind a flag; wdyt?
Hm, why is the complication necessary? Can't we just do something really
simple
and generic in the case where there actually is a duplicate? Doesn't
matter
that
it would be slow.
I don't really see a way to do this. If you want an abstraction between:
(1) the existing code where you can use a boilerplate object with
pre-filled
constant values, just emitting code to set things at runtime when needed,
trying
to collect getters and setters to avoid having to look up a getter at
runtime
when adding a setter and vice versa, and:
(2) a translation to "do () { var o = {}; o.foo = 20; o.bar = 30; o }"
If this is what you want, then you have to represent some of the aspects of
(1)
in the generic solution.
Particularly with duplicate properties we run into tricky semantic
corner-cases.
For example:
({ get foo() { 42 }, foo: 10, set foo(x) { ... } })
What does the resulting object look like? It has one property, "foo", and
it's
an accessor property, but does it have a getter? (In the above patch: it
does
not have a getter. However,-writing to es-discuss to clarify has not been
useful.)
Likewise:
({ get __proto__() { 42 }, __proto__: 10, set __proto__(x) { ... } })
Clearly the __proto__:10 sets the [[Prototype]]. But does it have a getter?
The state machine in ast.cc provides a fairly simple (though regrettably
verbose) way to answer these questions once in a central place, which I find
more better than the current state of things ;) It's also easy to extend
to the
computed property name case, with no impact on code generation either
(except
taking out some UNREACHABLE()s).
https://codereview.chromium.org/352173004/
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