As Ben stated, --disable-old-api-accessors makes them behave the same; but
it indeed makes SetAccessor work like SetNativeDataProperty.
The reason is that SetAccessor creates a pseudo-data-property that's backed
by accessors: Object.getOwnPropertyDescriptor(o, "p") will return something
that looks like a data property, not like an accessor. Data properties are
supposed to behave differently when on the prototype chain than accessors.
If there's a getter, we should call into it. If there's a setter, however,
we shouldn't call it. We should only check whether data properties on the
prototype chain are read-only, and thrown an exception if they are. That's
how data properties work.
If you want something similar to the old-style SetAccessor behavior, you
should instead use SetAccessorProperty. That creates an actual
getter/setter pair. That setter will be called through the prototype chain
as well, just like other accessors in JS.
The old behavior for SetAccessor is a v8-only invention that looks like a
data property but behaves like an accessor; which not only adds unnecessary
complexity, but is actually impossible to implement correctly in certain
cases.
HTH,
Toon
On Tue, Oct 24, 2017 at 5:49 PM J Decker <d3c...@gmail.com> wrote:
>
>
> On Tuesday, October 24, 2017 at 7:38:44 AM UTC-7, Ben Noordhuis wrote:
>
>> On Tue, Oct 24, 2017 at 3:32 PM, J Decker <d3c...@gmail.com> wrote:
>> >
>> > On Tuesday, October 24, 2017 at 3:40:31 AM UTC-7, Ben Noordhuis wrote:
>> >>
>> >> On Tue, Oct 24, 2017 at 5:53 AM, J Decker <d3c...@gmail.com> wrote:
>> >> >
>> >> > On Thursday, August 7, 2014 at 3:52:53 PM UTC-7, Ben Noordhuis
>> wrote:
>> >> >>
>> >> >> On Fri, Aug 8, 2014 at 12:10 AM, Flying Jester <foolki...@gmail.com>
>>
>> >> >> wrote:
>> >> >> > What precisely is the difference between using SetAccessor and
>> >> >> > SetNativeDataProperty?
>> >> >>
>> >> >> Nothing, as far as I know. The order of arguments is different but
>> >> >> they have identical implementations.
>> >> >
>> >> > They are not exactly the same... I've been using
>> SetNativeDataProperty,
>> >> > which works for getters, but when i started to use it for a setter,
>> V8
>> >> > ended
>> >> > up setting a property on the object instead of calling the setter.
>> >> > Changing
>> >> > to SetAccessor allows the setter to be called correctly.
>> >> >
>> >> > And while I realize this is a very old thread; it's about the only
>> one
>> >> > that
>> >> > shows up for 'SetNativeDataProperty vs SetAccessor'
>> >> >
>> >> > I can't find any other information that would indicate that
>> >> > setnativedataproperty shouldn't or doesn't work; other than my code.
>> >>
>> >> Blast from the past!
>> >>
>> >> I believe what I wrote still holds (or holds again) if you start V8
>> >> with `--disable_old_api_accessors`. It's currently off by default but
>> >> that will likely change someday.
>> >
>> >
>> > That option makes SetAccessor setter not work. It creates a property
>> on the
>> > object instead of calling the setter.
>> >
>> > psiTemplate2->PrototypeTemplate()->SetAccessor( String::NewFromUtf8(
>> > isolate, "text" )
>> > , ControlObject::getControlText, ControlObject::setControlText );
>> >
>> > So that's discouraging....
>>
>> With `--disable_old_api_accessors` they are quite literally the same
>> implementation. Something else must be going on. Out-of-date V8
>> version?
>>
>
> M:\javascript\vfs\native>node
> > process.version
> 'v8.4.0'
> > process.versions
> { http_parser: '2.7.0',
> node: '8.4.0',
> v8: '6.0.286.52',
> uv: '1.13.1',
> zlib: '1.2.11',
> ares: '1.10.1-DEV',
> modules: '57',
> nghttp2: '1.22.0',
> openssl: '1.0.2l',
> icu: '59.1',
> unicode: '9.0',
> cldr: '31.0.1',
> tz: '2017b' }
>
> I doubt it. It's not absolute bleeding edge, but it's pretty new.
>
> I was going to include the whole thing I'm trying to test, but expect that
> to fail so here's a super simple test
>
> https://github.com/d3x0r/test-accessor
>
> It sets a SetAccessor called 'text' and a SetNativeDataProperty called
> 'native'
>
> to build
> npm install .
>
> test1 : ( only setter called is SetAccessor settter )
> npm test
>
> (sample output)
> > node test.js
>
> plugin.cc: getter called... default value
> Default: default value
> plugin.cc: setter called... with newText
> plugin.cc: getter called... newText
> Default: [] newText
> plugin.cc: getter called... newText
> Default: newText
> Default: [ 'native' ] nativeText
>
>
> test2 : (passes --disable-old-api-accessors which makes neither setter
> get called )
> npm run test2
>
> (sample output)
> > node --disable-old-api-accessors test.js
>
> plugin.cc: getter called... default value
> Default: default value
> Default: [ 'text' ] newText
> plugin.cc: getter called... default value
> Default: default value
> Default: [ 'text', 'native' ] nativeText
>
>
>
>
>
> --------- what I would have sent ---------
>
> This is a node plugin - https://github.com/d3x0r/sack.vfs the new
> features I'm extending it with I can only confirm work under Windows.
>
>
> https://github.com/d3x0r/sack.vfs/blob/master/src/gui/sack_psi_module.cc#L415
> configures accessor on prototype here
>
> Which is tested with this line...
> https://github.com/d3x0r/sack.vfs/blob/master/tests/sack_test4.js#L28
> which should change the text in the resulting gui.
>
>
>
> --
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--
Toon Verwaest | Software Engineer, V8 | Google Germany GmbH | Erika-Mann
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