What the status of the ? and ! Option/Result return types?

[srackham]

On 11-Jul-2022 @medvednikov commented:

Option and Result have been split up: ?Foo and !Foo.

This seems to contradicted by the current documentation, which I'm guessing is out of date:

V combines Option and Result into one type, so you don't need to decide which one to use.

The same documentation also states:

If you don't need to return an error message, you can simply return none (this is a more efficient equivalent of return error("")).

There is also this RFC, updated 21-Apr-2022: Redesign of error and none handling but it's implementation status is unclear (to me).

From what I can tell things as they currently stand can be sumarised as follows:

• !T returns a Result type and should be used if you want to return a value or an error?
• ?T returns an Option type and should be used if you want to return a value or none?
• 3-way return types (value, none and error), which are currently allowed in ? functions, are deprecated?

See also #14664

[JalonSolov]

The status is... in transition.

?Type still works as it used to, but the changes are being made to separate ?Type and !Type.

The documentation will be updated when ?Type no longer works as it did in the past.

[srackham]

@JalonSolov Thanks. I'm assuming my summary was correct and from now on should code accordingly.

[JalonSolov]

Yes. The new way works already.