How to specify ListFormat instance options

[ryzokuken]

We have encapsulated a ListFormat instance inside DurationFormat in order to format the different duration components as a single list. How should we allow users to specify options for constructing that instance? Here are our options.

1. Don't specify any options for the instance.

Don't specify any options at all. Just instantiate a vanilla ListFormat with the same locale.

2. Implicit passthrough

Implicitly passthrough the options argument to the ListFormat constructor.

3. Explicit

Explicitly specify options for the ListFormat constructor, via an additional option listFormatOptions.

/cc @littledan @younies @sffc

Reference: #11 (comment)

[littledan]

My guess was that 2. would give the semantics we generally want. 1 seems broken, and 3 seems overkill/hard to use (but maybe there's some use case for it that I'm missing?).

[sffc]

Related: tc39/ecma402#422

I would prefer that we set the width of the ListFormat to match the width of the DurationFormat (long->long, short->short, narrow->narrow), and otherwise don't bubble up any other settings. I think this covers the 90% use case. When tc39/ecma402#422 is resolved, we can consider amending Intl.DurationFormat to pass down options in a similar way.

[ryzokuken]

@sffc that seems like exactly what Daniel had proposed, so I guess we can get consensus on that behavior.

[younies]

@ryzokuken , thanks for bringing this issue
I would prefer option 2. However, some options could not be populated directly, for example style: "dotted",

Therefore, let's discuss this issue next meeting and try to have a consensus about it.

[sffc]

FYI: Under the hood, the "dotted" form does not actually use ListFormat, or at least that form is not available as a general purpose ListFormat pattern.

[ryzokuken]

Yes, the ListFormat is used for all forms other than "dotted".

[younies]

Yes, therefore, we could not pass this argument directly to ListFormat

[ryzokuken]

@younies actually, the opposite. In the case of "dotted", we don't even construct a ListFormat so it's not really a problem to pass the argument directly to ListFormat.

[younies]

We have consensus on option 2.