Svelte action update doesn't trigger on classes about svelte HOT 4 CLOSED

The problem here is that for back compatibility actions are treated as coarse. When you pass an object it deeply reads it to retrigger everytime something changes.

however deep_read_state can't work with classes since getters and setters are not enumerable.

In theory we could check and access every getter on the prototype...i'll see if there's a decent way of doing it.

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Ugh i tried to do something like this

const is_object_literal =
	typeof value === 'object' && value !== null && value.constructor === Object;

if (STATE_SYMBOL in value) {
	deep_read(value);
} else if (!Array.isArray(value)) {
	if (is_object_literal && Object.keys(value).length === 0) {
		for (let key in value) {
			const prop = value[key];
			if (typeof prop === 'object' && prop && STATE_SYMBOL in prop) {
				deep_read(prop);
			}
		}
	} else {
		const keys = Object.getOwnPropertyDescriptors(Object.getPrototypeOf(value));
		for (const key in keys) {
			if (keys[key].get) {
				value[key];
			}
		}
	}
}

but there's Proxy involved so is_object_literal gives false positives and it messes with the legacy labeled statement.

Another option could be dynamically add a symbol property to every compiled class that enumerates the fields but it's a pretty involved modification so i would love to hear the opinion of the maintainers before going on 😄

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I don't think it should trigger in either case with fine-grained reactivity 🤔

With runes I would probably use an effect instead of the update function:

const myAction = (node, counter) => {
	$effect(() => {
		node.innerHTML = counter.value;
	});
}

REPL

from svelte.

We shouldn't change anything here. The rule is "POJOs are auto-fine-grained and classes are not", and we shouldn't make an exception for actions. If using actions + runes one shouldn't use the update return type but instead use $effect to react to changes.

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