Fix exporting a class instance as an entrypoint. #3715
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This should work:
```
class Foo {
async fetch(req, env, ctx) { ... }
}
export default new Foo();
```
But it had a slight bug: `validateHandlers()` did not report the `fetch` method as existing. This meant you couldn't actually deploy a worker defined this way as the upload validator on the server side would reject it for not implementing `fetch`.
I asked Claude Code to fix it (as a test... I knew what the problem was). Transcript: https://claude-workerd-transcript.pages.dev/validate-handlers
geelen
reviewed
Mar 13, 2025
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| // Then, check for methods in the prototype chain (like a class instance) | ||
| js.withinHandleScope([&]() { | ||
| collectMethodsFromPrototypeChain(jsg::JsObject(handle).getPrototype(js), methodSet); |
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So this is the meaningful line change in this PR, yeah? Previously you weren't walking the prototype chain for default exports, is that right? I guess I'm not super clear why default is special, I suppose historical reasons?
I presume worker.impl->statelessClasses includes both WorkerEntrypoint and ExportedHandler style exports, right? Or is ExportedHandler handled elsewhere?
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This should work:
But it had a slight bug:
validateHandlers()did not report thefetchmethod as existing. This meant you couldn't actually deploy a worker defined this way as the upload validator on the server side would reject it for not implementingfetch.I asked Claude Code to fix it (as a test... I knew what the problem was). Transcript: https://claude-workerd-transcript.pages.dev/validate-handlers