Host reject to freeze?

[Jack-Works]

It might be possible there is a host API like this:

const process = new Process('./native.so')
process.memory instanceof ArrayBuffer
process.memory.transferToImmutable() // or .detach()

Is this a case we want the host to be able to reject the detached behavior? (This also affects other APIs like transfer actually).

[ljharb]

I'm confused, how would this not work out of the box? If it's actually a proper instance of ArrayBuffer, then it'd be detachable; if it's not detachable, then it's not a proper instance of ArrayBuffer.

[Jack-Works]

I'm confused, how would this not work out of the box? If it's actually a proper instance of ArrayBuffer, then it'd be detachable; if it's not detachable, then it's not a proper instance of ArrayBuffer.

I mean, if there is a case that the host wants to reject the AB being detachable. this is like HostEnsureCanAddPrivateElement that limits the ability of adding a private field to a host object.

[ljharb]

Why would we want to consider a host hook when no use case for that has presented itself?

[Jamesernator]

I'm confused, how would this not work out of the box? If it's actually a proper instance of ArrayBuffer, then it'd be detachable; if it's not detachable, then it's not a proper instance of ArrayBuffer.

Why would we want to consider a host hook when no use case for that has presented itself?

Host buffers can already be non-detachable/transferable via [[ArrayBufferDetachKey]], e.g. WebAssembly.Memory can't be transfered/detached (except via other WebAssembly methods, e.g. mem.grow does detach the previous buffer):

const mem = new WebAssembly.Memory({ initial: 1 });
// Throws a TypeError
const newBuffer = mem.buffer.transfer();
const oldBuffer = mem.buffer;
mem.grow(1);
// Now detached
oldBuffer.detached; // true
oldBuffer === mem.buffer; // false

const mem = new WebAssembly.Memory({ initial: 1, maximum: 1 });
// Not detachable by any means
mem.buffer;

I don't see that this proposal needs anything special, if a host buffer can't be transfered to an immutable buffer then they can just set [[ArrayBufferDetachKey]] and provide a separate API.

[Jack-Works]

Thank you! This is first time I learn ArrayBufferDetachKey