Coercing 'this' (was: Topic list - pending changes and issues for the ES3.1 spec)
brendan at mozilla.org
Thu Sep 11 11:19:20 PDT 2008
On Sep 10, 2008, at 3:07 AM, Sam Ruby wrote:
> In such a scenario, is there value in providing a Decimal wrapper type
> at all?
So people can add methods that we did not think of to
Decimal.prototype. But you assumed static methods only, so perhaps
you meant to exclude this use-case.
Extending standard constructor prototypes is frowned upon currently
because such user-defined prototype properties are enumerable, but
Object.defineProperty/ies stand ready. And people do use this use-
case today, whether we like it or not.
> It occurs to me that the latter case (looking up after wrapping)
> trades a single wrapping at function entry against potentially
> multiple wrappings that may occur inside the function.
Wrapping must be done at most once, lazily on first |this| use if
possible but at most once only, per |this| parameter binding.
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