Update design

README.md

@@ -10,34 +10,90 @@ Stage: 1
 
 ## Presentations
 
-- [For stage 1 on 82th tc39 meeting (Apr 2021)](https://docs.google.com/presentation/d/1TGLvflOG63C5iHush597ffKTenoYowc3MivQEhAM20w/edit?usp=sharing)
-- [TC39 meeting notes on 82th tc39 meeting](https://github.com/tc39/notes/blob/master/meetings/2021-04/apr-21.md#read-only-arraybuffer-and-fixed-view-of-arraybuffer-for-stage-1)
+- [TC39 meeting notes on 82th tc39 meeting](https://github.com/tc39/notes/blob/main/meetings/2021-04/apr-21.md#read-only-arraybuffer-and-fixed-view-of-arraybuffer-for-stage-1) ([slides](https://docs.google.com/presentation/d/1TGLvflOG63C5iHush597ffKTenoYowc3MivQEhAM20w/edit?usp=sharing))
+- [TC39 meeting notes on 106 tc39 meeting](https://github.com/tc39/notes/blob/main/meetings/2025-02/) ([slides](https://docs.google.com/presentation/d/1u6JsSeInvm6F4OrmCSLubtDvFVdjw1ESeE5-c_YflHE/))
 
 ## Problem to be resolved
 
 All of the following are helpful to archive the minimal permission/information principle.
 
-1. Cannot make an `ArrayBuffer` read-only.
-2. Cannot give others a read-only view to the `ArrayBuffer` and keep the read-write permission internally.
-3. Cannot give others a view that range limited (only a small area of the whole buffer is visible).
+1. Cannot give others a read-only view to the `ArrayBuffer` and keep the read-write view internally.
+2. Cannot give others a view that range is limited.
+
+```js
+function createView() {
+    const buffer = new ArrayBuffer(128)
+    const offset = 4
+    const length = 16
+    const view = new Uint8Array(buffer, offset, length)
+    view[0] = 0x12
+    return view
+}
+
+const view = createView()
+// oops!
+const wholeBufferView = new Uint8Array(view.buffer)
+```
 
 ## Design goal
 
-1. Freeze the `ArrayBuffer`.
-    1. Like `Object.freeze`, there is no way back once frozen.
-    2. Any `TypedArray`/`DataView` to the freezed `ArrayBuffer` is read-only too.
-    3. [Optional] Keep frozen when sent across Realm (HTML intergration).
-2. Read-only `TypedArray`/`DataView` to a read-write `ArrayBuffer`.
+1. Read-only `TypedArray`/`DataView` to a read-write `ArrayBuffer`.
     1. Must not be able to construct a read-write view from a read-only view.
-3. [Optional] Range-limited `TypedArray`/`DataView` to a read-write `ArrayBuffer` ([CrimsonCodes0](https://github.com/CrimsonCodes0)'s [use case on WebAssembly](https://github.com/tc39/proposal-limited-arraybuffer/issues/11)).
+1. Range-limited `TypedArray`/`DataView` to a read-write `ArrayBuffer`.
     1. Must not be able to construct a bigger view range from a smaller view range.
-4. Not adding too much complexity to the implementor.
+1. Not adding too much complexity to the implementor.
+
+## Proposed changes
+
+1. New API on the `TypedArray`/`DataView` constructor.
+
+```ts
+interface TypedArrayConstructor {
+    new (buffer: ArrayBuffer, options?: TypedArrayConstructorOptionsBag): Uint8Array<ArrayBuffer>;
+}
+interface DataViewConstructor {
+    new (buffer: ArrayBuffer, options?: ViewConstructorOptionsBag): DataView<ArrayBuffer>;
+}
+interface ViewConstructorOptionsBag {
+    byteOffset?: number;
+    length?: number;
+    readonly?: boolean;
+    limited?: boolean;
+}
+```
+
+1. If `readonly` or `limited` is set, the view returned does not have a `.buffer` property on it.
+
+```ts
+const buffer = new ArrayBuffer(1024);
+const view = new Uint8Array(buffer, { limited: true, byteOffset: 12 });
+view.buffer; // undefined
+```
+
+1. If `readonly` is set, the `TypedArray` returned is an exotic object (behaves like a [`ModuleNamespaceExoticObject`](https://tc39.es/ecma262/multipage/ordinary-and-exotic-objects-behaviours.html#module-namespace-exotic-object)), the returned `DataView` throws for set functions.
+
+```ts
+const buffer = new ArrayBuffer(8);
+const view = new Uint8Array(buffer, { readonly: true });
+view.buffer; // undefined
+// view[0] = 1; // Error
+Object.getOwnPropertyDescriptor(view, 0);
+// { configurable: false, writable: true, enumerable: true, value: 0 }
+
+const view2 = new DataView(buffer, { readonly: true });
+view2.buffer; // undefined
+// view2.setUint8(0, 0); // Error
+```
 
-## Pros
+1. Change the constructor of `TypedArray` and `DataView`, to accept `TypedArray` and `DataView` as source.
 
-1. Minimal permission/information principle works on `ArrayBuffer`.
-2. Embedded JS engines can represent ROMs as read-only `ArrayBuffer`.
+```ts
+const buffer = new ArrayBuffer(128)
+const view = new Uint8Array(buffer, { offset: 16, length: 32, readonly: true })
 
-## API design
+const dataView = new DataView(view)
+dataView.setUint32(0, 1) // throws, inherits readonly, offset and length of `view`
 
-See [design.md](./design.md)
+const dataView2 = new DataView(view, 16, 16)
+// inherits readonly, offset += 16 (32 in total), length = 16
+```

index.html

@@ -2414,7 +2414,7 @@
 </ul></div><div id="menu-toggle"><svg xmlns="http://www.w3.org/2000/svg" style="width:100%; height:100%; stroke:currentColor" viewBox="0 0 120 120">
       <title>Menu</title>
       <path stroke-width="10" stroke-linecap="round" d="M30,60 h60  M30,30 m0,5 h60  M30,90 m0,-5 h60"></path>
-    </svg></div><div id="menu-spacer"></div><div id="menu"><div id="menu-search"><input type="text" id="menu-search-box" placeholder="Search..."><div id="menu-search-results" class="inactive"></div></div><div id="menu-pins"><div class="menu-pane-header">Pins</div><ul id="menu-pins-list"></ul></div><div class="menu-pane-header">Table of Contents</div><div id="menu-toc"><ol class="toc"><li><span class="item-toggle-none"></span><a href="#sec-demo-clause" title="This is an emu-clause"><span class="secnum">1</span> This is an emu-clause</a></li><li><span class="item-toggle-none"></span><a href="#sec-copyright-and-software-license" title="Copyright &amp; Software License"><span class="secnum">A</span> Copyright &amp; Software License</a></li></ol></div></div><div id="spec-container"><h1 class="version">Stage -1 Draft / February 7, 2022</h1><h1 class="title">Proposal Title Goes Here</h1>
+    </svg></div><div id="menu-spacer"></div><div id="menu"><div id="menu-search"><input type="text" id="menu-search-box" placeholder="Search..."><div id="menu-search-results" class="inactive"></div></div><div id="menu-pins"><div class="menu-pane-header">Pins</div><ul id="menu-pins-list"></ul></div><div class="menu-pane-header">Table of Contents</div><div id="menu-toc"><ol class="toc"><li><span class="item-toggle-none"></span><a href="#sec-demo-clause" title="This is an emu-clause"><span class="secnum">1</span> This is an emu-clause</a></li><li><span class="item-toggle-none"></span><a href="#sec-copyright-and-software-license" title="Copyright &amp; Software License"><span class="secnum">A</span> Copyright &amp; Software License</a></li></ol></div></div><div id="spec-container"><h1 class="version">Stage -1 Draft / February 22, 2025</h1><h1 class="title">Proposal Title Goes Here</h1>
 
 <emu-clause id="sec-demo-clause">
   <h1><span class="secnum">1</span> This is an emu-clause</h1>
@@ -2424,7 +2424,7 @@ <h1><span class="secnum">1</span> This is an emu-clause</h1>
       <h1><span class="secnum">A</span> Copyright &amp; Software License</h1>
 
       <h2>Copyright Notice</h2>
-      <p>© 2022 Your Name(s) Here</p>
+      <p>© 2025 Your Name(s) Here</p>
 
       <h2>Software License</h2>
       <p>All Software contained in this document ("Software") is protected by copyright and is being made available under the "BSD License", included below. This Software may be subject to third party rights (rights from parties other than Ecma International), including patent rights, and no licenses under such third party rights are granted under this license even if the third party concerned is a member of Ecma International. SEE THE ECMA CODE OF CONDUCT IN PATENT MATTERS AVAILABLE AT https://ecma-international.org/memento/codeofconduct.htm FOR INFORMATION REGARDING THE LICENSING OF PATENT CLAIMS THAT ARE REQUIRED TO IMPLEMENT ECMA INTERNATIONAL STANDARDS.</p>