Adds props for ExecutionContext for ExportedHandler

[NejcZdovc]

Resolving #5617

More info with detailed description in #5617

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[NejcZdovc]

I have read the CLA Document and I hereby sign the CLA

[danlapid]

@penalosa

[penalosa]

I don't think this name is correct. As I understand it this PR is adding the option to drill the type of props through ExportedHandler? If so, the type parameter should be called Props

[NejcZdovc]

@penalosa should I call it ExecutionContextProps?

[penalosa]

@NejcZdovc I think it should just be called Props

[NejcZdovc]

@penalosa changed it to Props

[kentonv]

It should just be called Props. That's what it's called e.g. on the WorkerEntrypoint class and all the other places it appears -- it's not specific to ExecutionContext.

I'm a bit concerned that we're adding this as the fourth parameter to ExportedHandler when the second and third parameters are things that people are much less likely to want to customize. QueueHandlerMessage in particular is rarely overridden. I wonder if we should rethink this type signature entirely, maybe behind a compat flag.

@penalosa What do you think?

[penalosa]

@kentonv I agree, I think we should make this match WorkerEntrypoint (Env, then Props) behind a compat flag. It's probably worth getting this in as-is and then following up with that though, so that people on an older compat date are at least able to set the type of props (even if it's unergonomic)?

[kentonv]

Well, the reason I figured I could skip this entirely is because people using ctx.props should almost always be using WorkerEntrypoint, not ExportedHandler.

I would like to understand the use case here better -- I asked a question on the issue #5617.

[jamesopstad]

Thanks for the contribution. I can approve this once the email handler types have also been updated. I'll also make a note that we should consider changing the type parameter order in future.

[jamesopstad]

EmailExportedHandler also needs updating here:

workerd/types/defines/email.d.ts

Lines 63 to 67 in 903cdf1

	declare type EmailExportedHandler<Env = unknown> = (
	message: ForwardableEmailMessage,
	env: Env,
	ctx: ExecutionContext
	) => void | Promise<void>;