domenic at domenicdenicola.com (2013-08-02T20:43:00.347Z)
On Wed, Jul 31, 2013 at 5:47 AM, Erik Arvidsson <arv at google.com> wrote: > Also useful for methods where different subclasses needs to specialize the > behavior. > > We've tripped on the method use case before. Let's not repeat that mistake. Hi Erik, I'm missing your point. Could you give an example? Thanks.
On Wed, Jul 31, 2013 at 5:47 AM, Erik Arvidsson <arv at google.com> wrote: > > On Jul 31, 2013 1:39 AM, "Mark S. Miller" <erights at google.com> wrote: > > > > > > > > > > On Tue, Jul 30, 2013 at 9:19 PM, Brendan Eich <brendan at mozilla.com> > wrote: > >> > >> Mark Miller wrote: > >> > >>> On Tue, Jul 30, 2013 at 8:36 PM, Brendan Eich <brendan at mozilla.com<mailto: > brendan at 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, > > > > > > Only useful for instance-private instance variables, in which case you > may as well use lexically captured per-instance state. > > Also useful for methods where different subclasses needs to specialize the > behavior. > > We've tripped on the method use case before. Let's not repeat that mistake. > Hi Erik, I'm missing your point. Could you give an example? Thanks. > >> |this| after suitable instanceof tests with no mutable [[Prototype]] > (e.g., A and B are sealed, manually in ES6 alas, but still doable). > > > > > > Doesn't resist theft by proxy, since one can easily construct a proxy > that passes that instanceof test. > > > > > >> > >> > >> > >> /be > > > > > > > > > > -- > > Cheers, > > --MarkM > -- Cheers, --MarkM -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.mozilla.org/pipermail/es-discuss/attachments/20130731/2403aa24/attachment-0001.html>