The change to pointer receivers in 2.6 breaks the core functionality in a sinister and silent way

[fireynis]

It makes the old function calls like AddDays or AddYearsNoOverflow work completely differently. In the past, you could call them and the durations would be applied and a new struct was returned, leaving the original untouched. Now calling them returns a struct but also mutates the underlying struct that we are acting on. This means updating to 2.6 is a MASSIVE undertaking if this package is used throughout a reasonably large codebase.

This is a bit beyond a breaking change, this should be a v3, its completly changed the value and operation of the package as it is. Also this was not brought up as a breaking change. The questions are

1. Why switch this behaviour?
2. What is the path forward for using this package like we used to?

[kuafuRace]

This is a good question. Since v2.6, we have changed from a value receiver to a pointer receiver in order to improve performance and simplify the logic of customizing the time field output format when MarshalJSON and UnmarshalJSON. This is a major breaking update that should theoretically be upgraded to the v3, but in golang, v3 and v2 are completely different packages and we do not want to distribute the package, so we upgraded to v2.6. It is recommended to upgrade to v2.6, which provides the Copy method to avoid issues such as

c1 := carbon.Parse("2020-08-05 13:14:15")
c2 := c1.Copy().AddDays(2)

[fireynis]

We have added Copy everywhere but like this is a massive behaviour change, we have had to add Copy to basically everywhere we use this, I get that v3 is a different package, but this IS a different package. I had to make a massive PR from a minor version change which is a huge problem. Also thank goodness my tests caught this or I could have had billing be out by MONTHS.

[kuafuRace]

Sorry for the inconvenience caused. Currently, only the methods in "traveler.go" file change the original value, and we have made a prominent note in the document https://carbon.go-pkg.com/usage/traveler.html

[fireynis]

I wanted to come back and say thank you, it looks like in 2.6.14 you solved this by doing the Copy in the traveler functions, which was very clever. Appreciate you resolving this!