Patching from another instance of the same case class

[rpiaggio]

Thank you for this great library! It's incredibly useful together with Diode+React.

Here's a suggestion, which I think naturally falls within the domain of chimney: Being able to patch a case class instance from another instance, specifying the fields to patch. It can be seen as nicer syntax for .copy(...) specifying override fields from the other instance.

For example:

user.patchFrom(anotherUser, _.email, _.phone, _.address)

which would be equivalent to:

user.copy(email = anotherUser.email, phone = anotherUser.phone, address = anotherUser.address)

Thank you!

[krzemin]

Sounds good 👍

[rpiaggio]

Thank you @krzemin. Upon further thought, the patcher could be abstracted away for reusability (or reusability of the code that applies it):

val patcher = PatcherFor[User](_.email, _.phone, _.address)
user.patchFrom(patcher)(anotherUser)

(Might make sense to curry the application too).

[MateuszKubuszok]

Depends on #538 which in turns depends on #115.