On Mon, Mar 26, 2012 at 6:23 PM, Allen Wirfs-Brock <[email protected]> wrote: > As a followup, I've written a strawman[1] that explains how we could specify > and implement operator overloading that supports an open-ended set of value > types. I look at this as an adjunct to Dave's proposal that suggests that > the coercion/promotion rules should be pushed out of the actual operator > semantics and placed into an extensible set of methods. > > [1] http://wiki.ecmascript.org/doku.php?id=strawman:operator_overloading_with_double_dispatch
Python (and others, like my own slow homebrew version of operator overloading in JS) provide all binary operations as 'foo' and 'rfoo'. If the lvalue overloads 'foo', that's used. Otherwise, if the rvalue overloads 'rfoo', that's used. This makes it easier to define symmetric operations without having to monkeypatch another class. It's limited, of course, since you have to ensure that the lval doesn't preempt you with its own overload that doesn't understand how to use you. In the future when we have guards (and, presumably, guard-based overloads), this limitation can be avoided as well. ~TJ _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
