Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

make @@toStringTag and constructor prototype properties funky accessors #287

Merged
merged 4 commits into from
Dec 4, 2023
Merged

make @@toStringTag and constructor prototype properties funky accessors #287

Changes from 1 commit
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
e298671
make @@toStringTag and constructor prototype properties funky accessors
michaelficarra Sep 18, 2023
f481720
throw instead of silently doing nothing
michaelficarra Oct 12, 2023
7d48c43
throw when this value is Iterator.prototype
michaelficarra Oct 12, 2023
d741076
rewrite funky setter and extract as an AO
michaelficarra Oct 17, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Jump to
Jump to file
Failed to load files.
Diff view
Diff view
59 changes: 56 additions & 3 deletions spec.html
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -289,7 +289,35 @@ <h1>Iterator.prototype</h1>

<emu-clause id="sec-iteratorprototype.constructor">
<h1>Iterator.prototype.constructor</h1>
<p>The initial value of %Iterator.prototype%.constructor is %Iterator%.</p>
<p>`Iterator.prototype.constructor` is an accessor property with attributes { [[Enumerable]]: *false*, [[Configurable]]: *true* }. The [[Get]] and [[Set]] attributes are defined as follows:</p>

<emu-clause id="sec-get-iteratorprototype-constructor">
<h1>get Iterator.prototype.constructor</h1>
<p>The value of the [[Get]] attribute is a built-in function that requires no arguments. It performs the following steps when called:</p>
<emu-alg>
1. Return %Iterator%.
</emu-alg>
</emu-clause>

<emu-clause id="sec-set-iteratorprototype-constructor">
<h1>set Iterator.prototype.constructor</h1>
<p>The value of the [[Set]] attribute is a built-in function that takes an argument _v_. It performs the following steps when called:</p>
<emu-alg>
1. Let _O_ be ? RequireObjectCoercible(*this* value).
1. If _O_ is %Iterator.prototype%, then
1. Return *undefined*.
1. Let _desc_ be ? _O_.[[GetOwnProperty]](*"constructor"*).
1. If IsDataDescriptor(_desc_) is *true* and _desc_.[[Writable]] is *false*, then
1. Return *undefined*.
Copy link
Collaborator

@bakkot bakkot Sep 26, 2023 •
edited

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Per request of @erights this should be an error, to emulate strict rather than sloppy assignment.

1. Let _newDesc_ be the PropertyDescriptor { [[Value]]: _v_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }.
1. Perform ? _O_.[[DefineOwnProperty]](*"constructor"*, _newDesc_).
1. Return *undefined*.
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

if we're really going to do this it should be an AO that many things can share, since the only things that potentially change are Iterator.prototype and the property name

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

that can be an editorial thing we address in the PR to 262

</emu-alg>
</emu-clause>

<emu-note>
<p>Unlike the *"constructor"* property on most built-in prototypes, for web-compatibility reasons this property must be an accessor.</p>
</emu-note>
</emu-clause>

<emu-clause id="sec-iteratorprototype.map">
Expand Down Expand Up @@ -563,9 +591,34 @@ <h1>Iterator.prototype.find ( _predicate_ )</h1>

<emu-clause id="sec-iteratorprototype-@@tostringtag">
<h1>Iterator.prototype [ @@toStringTag ]</h1>
<p>The initial value of the @@toStringTag property is the String value "Iterator".</p>
<p>`Iterator.prototype[@@toStringTag]` is an accessor property with attributes { [[Enumerable]]: *false*, [[Configurable]]: *true* }. The [[Get]] and [[Set]] attributes are defined as follows:</p>

<emu-clause id="sec-get-iteratorprototype-@@tostringtag">
<h1>get Iterator.prototype [ @@toStringTag ]</h1>
<p>The value of the [[Get]] attribute is a built-in function that requires no arguments. It performs the following steps when called:</p>
<emu-alg>
1. Return *"Iterator"*.
</emu-alg>
</emu-clause>

<emu-clause id="sec-set-iteratorprototype-@@tostringtag">
<h1>set Iterator.prototype [ @@toStringTag ]</h1>
<p>The value of the [[Set]] attribute is a built-in function that takes an argument _v_. It performs the following steps when called:</p>
<emu-alg>
1. Let _O_ be ? RequireObjectCoercible(*this* value).
1. If _O_ is %Iterator.prototype%, then
1. Return *undefined*.
1. Let _desc_ be ? _O_.[[GetOwnProperty]](@@toStringTag).
1. If IsDataDescriptor(_desc_) is *true* and _desc_.[[Writable]] is *false*, then
1. Return *undefined*.
1. Let _newDesc_ be the PropertyDescriptor { [[Value]]: _v_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }.
1. Perform ? _O_.[[DefineOwnProperty]](@@toStringTag, _newDesc_).
1. Return *undefined*.
</emu-alg>
</emu-clause>

<emu-note>
<p>Unlike the @@toStringTag on most built-in classes, for web-compatibility reasons this property must be writable.</p>
<p>Unlike the @@toStringTag property on most built-in prototypes, for web-compatibility reasons this property must be an accessor.</p>
</emu-note>
</emu-clause>
</emu-clause>
Expand Down