On Nov 13, 2012, at 10:35 PM, Brendan Eich wrote: > Erik Arvidsson wrote: >> On Tue, Nov 13, 2012 at 3:25 PM, Tom Van Cutsem <[email protected] >> <mailto:[email protected]>> wrote: >> >> >> So, my proposal: let's revert the fundamental traps of Handler to >> become abstract methods again. This forces subclasses of Handler >> to provide all fundamentals at once, avoiding the footgun. >> >> >> Maybe we should skip the derived traps for ES6 and see if the extra >> allocation really becomes an issue in reality? This way we are keeping the >> API smaller and the risk of errors lower. We can always add the derived >> traps later, can't we? > > Allocations always matter, in my experience -- even with V8. > > Also Tom's point about precision counts, independent of allocations. A > "hasOwn" test in the MOP should not call the same thing that > Object.getOwnPropertyDescriptor calls, if we can help it -- especially > without a flag argument to hint the difference, but that flag argument is > blecherous anyway. >
A less blecherous flag might be as follows getOwnPropertyDescriptor: function(target, name, populate=true) -> desc | undefined If populate is false, the returned property descriptor doesn't need to be populated with the properties that describe attributes. In that case it must be a frozen object. This allows a preallocated descriptor to be used to indicate the existence of a property. It also removes the blechiness of using an argument to steer the return type of the function. Allen _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
