Very strange behavior. What's the rationale? To avoid a shadowing? To
avoid typo-errors -- i.e. if a user uses assignment it may be
occasionally and if he uses Object.defineProperty -- he really wants to
do it? Looks inconsistently. Assignment always affected an own property
(only if the property isn't an accessor, then of course it affects the
parent object).
Dmitry.
On 17.02.2011 5:02, Allen Wirfs-Brock wrote:
They can be over-ridden by Object.defineOwnProperty. they cannot be
over-ridden by assignment. See ES5 [[CanPut]] specification 8.12.4.
step 8.b
On Feb 16, 2011, at 5:32 PM, Irakli Gozalishvili wrote:
Thanks for the reply Allen,
I was under the impression that inherited properties can be
overridden, regardless of their write-ability on the __proto__.
Also as far as I understand freeze will make properties including
constructor non-confugurable, will I still be able to override such
properties using Object.defineProperty ?
Also this was simplified example and it's not really possible to do
the freeze after. Will try `Object.defineProprety` though.
Thanks
--
Irakli Gozalishvili
Web: http://www.jeditoolkit.com/
Address: 29 Rue Saint-Georges, 75009 Paris, France
<http://goo.gl/maps/3CHu>
On Thu, Feb 17, 2011 at 02:21, Allen Wirfs-Brock
<[email protected] <mailto:[email protected]>> wrote:
The error looks correct to me. By freezing Type.proto you make
all its own properties "read only". One of those is the
constructor that is automatically created on every func.prototype
object. When you assign to object.constructor you are trying to
over-ride an inherited read-onoy property. ECMAScript has never
allowed this. You can say:
Object.defineProperty(object,"constructor",{value: function
Foo() {}, /* any other attributes you want to set */});
to over-ride the inherited constructor property.
Or you can restructure you code so you do the freeze after you do
the assignment.
On Feb 16, 2011, at 5:09 PM, Irakli Gozalishvili wrote:
Hi,
I've run into one issue and even after reading ES5 specs several
times it's not clear to me what should be an expected behavior:
Currently on Firefox nightly following code:
(function() {
"use strict";
function Type() {}
Object.freeze(Type.prototype);
var object = Object.create(Type.prototype);
object.constructor = function Foo() {};
return object
})();
throws TypeError: object.constructor is read-only
while on chrome
it returns object with constructor Foo
I would like to know what is an expected behavior to fill a bug
to an appropriate project.
Thanks!
--
Irakli Gozalishvili
Web: http://www.jeditoolkit.com/
Address: 29 Rue Saint-Georges, 75009 Paris, France
<http://goo.gl/maps/3CHu>
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