Should a no-required-member dictionary argument always be optional regardless of its position?

[saschanaz]

What is the issue with the Web IDL Standard?

https://webidl.spec.whatwg.org/#idl-operations

and the argument is either the final argument or is followed only by optional arguments, then the argument must be specified as optional and have a default value provided.

But why such requirement? Web IDL doesn't have requirement that a required argument cannot follow an optional argument, that this is possible:

undefined operation(optional OptionalDict dict = {}, DOMString str);

But because of that requirement we allow this too:

undefined operation(OptionalDict dict, DOMString str);

which is weird? One can say such function signature is weird too though.

[domenic]

I'm not sure I fully understand what you're proposing. But if I had to guess, you are saying that

undefined operation(optional OptionalDict dict = {}, DOMString str);

is good (since it allows obj.operation(undefined, "string") to trigger the default. And

undefined operation(OptionalDict dict, DOMString str);

is bad, since it prohibits obj.operation(undefined, "string") for no reason.

If that is what you are saying, I agree. We should require it to be optional regardless of the position.

I am curious if this affects any existing APIs.

[saschanaz]

That's exactly what I tried to say, thanks for clarifying!

I am curious if this affects any existing APIs.

I'll check whether modifying the existing validation in webidl2.js causes error in any spec.