time: enhancement: parse ISO 8601-formatted durations

[mcandre]

ISO 8601 provides a standard for representing time durations in a human-readable format:

https://en.wikipedia.org/wiki/ISO_8601#Durations

Could we offer a method for parsing ISO 8601 formatted durations, similar to how the Go time library parses ISO 8601 instantaneous points in dates and times?

[ianlancetaylor]

The usual process would be to write this as an external library first, and then we can consider whether to pull it into the standard library.

[slinkydeveloper]

That's something we're looking for too knative/eventing#3555

[souenzzo]

Can https://github.com/rickb777/date be considered the external library first ?!

The parser function is here:
https://github.com/rickb777/date/blob/master/period/parse.go#L39

[andoks]

Some other libraries and software in Go that attempts to parse/output ISO periods:

• https://github.com/dylanmei/iso8601
• https://github.com/ChannelMeter/iso8601duration
• https://github.com/senseyeio/duration
• https://github.com/rickb777/period
• https://github.com/BrianHicks/finch/blob/develop/duration/duration.go#L33
• https://github.com/sosodev/duration

[andoks]

There is an ongoing discussion regarding adding ISO 8601 format support in json/v2 here: #63397 (comment)

Might be worth chiming in over there, perhaps upvoting the comment to signal the level of demand for this feature.