Duration.fromISOTime('0:00') --> can't be parsed

[carstenfuchs]

Describe the bug The attempt to create a Duration with fromISOTime() fails whenever the hours are not two digits.

(As a side note: the attempt to create a Duration from time 50:00 works. See example below.)

To Reproduce These are all invalid:

luxon.Duration.fromISOTime("0:00")
luxon.Duration.fromISOTime("1:00")
luxon.Duration.fromISOTime("222:00")

Observe that in contrast, this is valid:

luxon.Duration.fromISOTime("50:00")

Actual vs Expected behavior All of these should result in valid Durations:

luxon.Duration.fromISOTime("0:00")
luxon.Duration.fromISOTime("1:00")
luxon.Duration.fromISOTime("222:00")

(Alternatively, "50:00" should be invalid.)

Desktop (please complete the following information):

• OS: Ubuntu 22.04 LTS
• Browser: Firefox 115.0
• Luxon version: 3.3.0
• Your timezone: "Europe/Berlin"

Additional context In my opinion, the root cause of this problem is that times and durations are not actually compatible:

While a time such as 25:00 does not make sense (and is not covered by ISO 8601), a duration of 25 hours does. Specifying durations with hours, minutes and seconds in the form HH:MM:SS.s also makes sense, but should not be limited to the limits of times given in the same form. (Strictly spoken, the method name fromISOTime() is an antagonism: it should possibly be named fromHours() or similarly.)

In summary, my proposal is to relax Duration.fromISOTime() to accept all of the examples above, that is, hours that have one, two or more digits.

[diesieben07]

ISO refers to ISO 8601, which requires leading zeros. However you are correct in that fromISOTime should technically not accept invalid times of day (such as your example 50:00). It is debatable whether we should make fromISOTime produce an invalid Duration for invalid times of day and if that is worth the breaking change. ISO 8601 specifies a different format for actual durations (unrelated to time of day), which can be parsed by Duration.fromISO.

[carstenfuchs]

Yes, I think that there are two “clean” solutions for this:

1. Either strictly apply ISO 8601, which would cause times such as 50:00 (that are valid today) to become invalid.
2. Further relax (or, in a sense, forego) the ISO 8601 rules so that examples such as 0:00 or 123:45 become valid.

It would be ideal if there was a standards or normative reference for durations that are given in this form, but I've not be able to find any (maybe DIN 5008 has more than I have been able to dig up?) But even without such a normative reference, I think that the 2. option, relaxing the rules, would be the right choice for the following reasons:

• For durations a notation can be used that looks the same or very much like the notation that is used for times, e. g. 11:23 is a valid example for both, but durations and times are conceptually entirely different subjects. Personally, I think that it is self-suggesting to use time formatting also for formatting durations, but it is generally rather by accident than by intention that time formatting limitations are also forced upon durations.
• One characteristic of times and durations being different is that durations can be added, but times cannot: Adding durations 12:00 and 13:00 yields a valid duration, but adding times 12:00 and 13:00 is undefined.
• Well … sport events such as soccer matches that have a length of 1 hour and 30 minutes are given as 90:00 … Yes, this is besides the point. But I think that enough real world examples exist where durations of more than 24 hours are given in HHH:MM form.