Extract cargo/handling.go to its own package.

[marcusolsson]

Make

cargo.HandlingActivity
cargo.HandlingEvent
cargo.HandlingHistory

into

handling.Activity
handling.Event
handling.History

[marcusolsson]

This is probably more of a nice-to-have. It will probably result bigger consequences on the domain model than what's warranted.

[marcusolsson]

This is an answer to this tweet:

In the original sample app, there's a separate handling package but due to circular dependencies (Delivery -> HandlingEvent -> Cargo), I have merged the handling package into the cargo one.

This is most likely impossible to resolve without a non-trivial redesign. The best way would obviously be to avoid circular deps from the start. So far, I've wanted to keep as much of the original design as possible, but this issue might deserve diverging a bit from that design.

[seanpianka]

Hi @marcusolsson, is this not possible by replacing the "TrackingID" type with just "ID" type? I don't see why maintaining this dependency is worthwhile (or if it should be emulated in other projects) purely to more specifically describe what kind of ID an ID is.