add a Duration::toDateInterval and Duration::fromDateInterval methods

[nyamsprod]

For interoperability you should also add the following methods to the Duration class:

• Duration::toDateInterval
• Duration::fromDateInterval

[ocram]

Definitely, thank you!

For toDateInterval, one solution would be to call Duration#toIso8601 and pass the resulting string to the constructor of the DateInterval class.

For fromDateInterval, do you think it should just read the properties from a DateInterval instance and pass them to Duration::fromDateTime? We should probably pay special attention to the days property on the DateInterval instances that is set only when the instances are the result of a diff.

[nyamsprod]

yes indeed the days property is the one to pay attention to. :)