Re: [v8-users] Is it safe to consume v8::Private methods?

2017-07-14 Thread Jakob Kummerow 
Gautham, I think you might be misunderstanding how the Maybe<> API is
supposed to be used. When used correctly, it is absolutely safe and will
never crash.

- Maybe::FromJust() / MaybeLocal::ToLocalChecked() are intended for when
you know for sure that the Maybe / MaybeLocal is not empty. Usually, the
only case when you would know that is when you've just checked.
- Maybe::IsNothing() / Maybe::IsJust() / MaybeLocal::IsEmpty() are intended
for doing precisely that check.

Typical usage looks like:

MaybeLocal result = ...;
if (result.IsEmpty()) {
  // Handle error case, e.g. print a warning.
  return false;
} else {
  // .ToLocalChecked is safe to use here :-)
  do_something_with(result.ToLocalChecked());
}

For convenience, there are also the Maybe::FromMaybe() /
MaybeLocal::ToLocal() helpers:

Maybe maybe_x = ...;
int x = maybe_x.FromMaybe(-1);
// same as:
// int x = maybe_x.IsJust() ? maybe_x.FromJust() : -1;

Of course you can also use Private Symbols if you prefer; but there's
really no reason to avoid private fields for stability reasons.

Hope this helps,
Jakob

On Fri, Jul 14, 2017 at 12:00 AM, Ben Noordhuis  wrote:

> On Fri, Jul 14, 2017 at 5:52 AM, Gautham B A
>  wrote:
> > No, .ToLocalChecked() is called by my code, not from V8.
> >
> > I would like to know if the APIs under v8::Private namespace has been
> battle
> > tested.
>
> Node.js uses them and I'm fairly sure Chromium does too, so yes, I
> think you can say it's battle tested.
>
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[v8-users] Intent to ship: allowing invalid escape sequences in tagged template literals

2017-07-14 Thread no spoon 
Contact email: bak...@gmail.com

Spec: https://tc39.github.io/proposal-template-literal-revision/

This feature is stage 4 and will be included in the 2018 edition of
ECMA-262.

Summary: ES6 template literals forbid certain escape sequences, like
`\u{not hex}`. But tagged templates expose to user code the raw code points
of the template literal, and some applications only care about those. As
such, this stage 4 TC39 proposal allows such invalid escape sequences in
tagged template literals. The "cooked" value of such a template (that is to
say, with escape sequences interpreted), which is also exposed to user
code, is `undefined`.

Interop risk: This new language feature allows syntax that was previously a
SyntaxError, so compatibility risk is low.

Firefox has shipped this feature (
https://bugzilla.mozilla.org/show_bug.cgi?id=1317375 ).
Safari has implemented this feature (
https://bugs.webkit.org/show_bug.cgi?id=166871 ) and shipped it in at least
Tech Preview.
Edge has not implemented this feature (
https://github.com/Microsoft/ChakraCore/issues/2344 ).

Tracking bug: https://bugs.chromium.org/p/v8/issues/detail?id=5546

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[v8-users] How to call js function from C++ with default recv value?

2017-07-14 Thread Bogdan Padalko 
Hi, I'm trying to deal with a case when user pass Function callback to C++ 
and it needs to be invoked from that C++ respecting this value, So 
Function::Call() does not fulfill this requirement.

Are there any change to achieve that without creating new Script and run it 
within a new Context with, e.g. 'fnc(...args)' where fnc is callback user 
provided and args are function arguments to call it with, both set on 
global object of this context?

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Re: [v8-users] Is it safe to consume v8::Private methods?

2017-07-14 Thread Ben Noordhuis 
On Fri, Jul 14, 2017 at 5:52 AM, Gautham B A
 wrote:
> No, .ToLocalChecked() is called by my code, not from V8.
>
> I would like to know if the APIs under v8::Private namespace has been battle
> tested.

Node.js uses them and I'm fairly sure Chromium does too, so yes, I
think you can say it's battle tested.

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