Private Slots

Mark S. Miller erights at
Wed Jan 16 12:15:04 PST 2013

On Wed, Jan 16, 2013 at 11:47 AM, Brandon Benvie
<brandon at> wrote:
> To compare the various scenarios, this is what (I believe) it looks like for
> SES. In ES5, SES currently censors gOPN I believe, in order to implement the
> equivalent of private keys and/or WeakMap.

SES includes all API defined in std ES5 including gOPN. On platforms
without built-in WeakMaps, SES does virtualize gOPN as part of its
emulation of WeakMaps, but that should be completely invisible to the
SES user. SES currently only seeks to be like ES5+WeakMaps. It does
not currently attempt to emulate private or unique symbols.

> Given an ES6 runtime environment
> that only supported unique symbols, it would have to censor getOwnKeys and
> filter symbols if they were present in a blacklist Set. Given an ES6 runtime
> environment with private symbols, SES wouldn't have to censor either.


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