This behaviour seems to result in undesirable behaviour in conjunction with
object literals:
Object.defineProperty(Object.prototype, "foo", {value:"bar"});
"use strict"; var someObject = {foo:"wibble"}
Will now throw.
--Oliver
On Feb 16, 2011, at 6:02 PM, 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
>>
>>
>> On Thu, Feb 17, 2011 at 02:21, Allen Wirfs-Brock <[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
>>> _______________________________________________
>>> es-discuss mailing list
>>> [email protected]
>>> https://mail.mozilla.org/listinfo/es-discuss
>>
>>
>
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