Major refactor

• Current version of proposal has one AO, PartitionDurationFormatPattern, that has hard-to-read / hard-to-implement complexities
• Most of these complexities are related to the need for special handling when formatting units with "numeric" and "2-digit" styles
• The complexity of this AO has proved quite annoying for implementors

Major refactor

• Refactor splits out handling for these styles into new AOs
• Additional refactor in progress: simplifyFormatNumericUnits AO

Why are "numeric"-like styles difficult?

• All other duration unit styles produce separated lists (in 'en' these lists separated by commas and/or “and”)
• "numeric"-like styles produce output resembling the display on a digital clock, with hour/minute and minute/second separators between them

• df = new Intl.DurationFormat('en', {style: "short"}).format({hours: 1, minutes: 2, seconds: 3}) --> "1 hr, 2 min, 3 sec"
• df = new Intl.DurationFormat('en', {hours: "numeric"}).format({hours: 1, minutes: 2, seconds: 3}) --> "1:02:03"

Why are "numeric"-like styles difficult?

• "numeric"-like formatting is a fundamentally different task than formatting the other styles, and the steps for handling it are likewise different
• Previously the steps for "numeric"-like and non-"numeric"-like had been intermixed, producing most of the frustrating complexity

Other editorial (?) changes

• Alongside the refactor are potentially normative changes related to "numeric"-like formatting.
• Several new slots for locale-dependent information introduced, (largely) in preparation for a hypothetical DurationFormat.v2

Other editorial (?) changes

• [[HoursMinutesSeparator]] and [[MinutesSecondsSeparator]]
  • Some locales use different separators between hours/minutes and minutes/seconds.
  • For example, fr-CA uses ‘h’ between hours and minutes, and ‘m’ between minutes and seconds

Other editorial (?) changes

• [HoursDigits]]
  • Some locales, notably ‘af’, use two-digit hours for clock-style formatting, i.e. “07:00” instead of “7:00”. This slot allows us to produce properly-formatted output for those locales

Other editorial (?) changes

• To ensure that this update is purely editorial, the current version has a note saying that [[HoursMinutesSeparator]] and [[MinutesSecondsSeparator]] must be the same, and a note saying that [[HoursDigits]] must be 1

Reasoning

• Need to avoid major normative changes while at Stage 3
• However: Because both of these changes are about correctly formatting durations for all locales, this could be conceptualized as a bugfix

Thanks!