Mark Miller wrote:
On Tue, Jul 30, 2013 at 8:36 PM, Brendan Eich <bren...@mozilla.com
<mailto:bren...@mozilla.com>> wrote:
Mark S. Miller wrote:
Aside from this confinement issue, all other the advantages
that unique symbols have over unique-ish strings seem minor to
me. The biggest is default non-enumerability, when we're
getting away (admittedly slowly) from enumerability being
significant anyway. IMO, if the only advantages of unique
symbols over unique-ish strings are these minor ones, then
they don't pull their weight.
However, I don't understand the confinement scenario you have
in mind. Can you give an example?
A friend field a la C++ "friend", e.g.:
module ... {
const friend = Symbol(); // however it's spelled
class A { ... }
class B { ... }
}
where fiend is used in the ... elisions but only to access
properties of objects known to be instanceof A or B.
Known how?
Lots of ways, e.g., |this| in bound methods, |this| after suitable
instanceof tests with no mutable [[Prototype]] (e.g., A and B are
sealed, manually in ES6 alas, but still doable).
/be
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