OnSourcing

A sourcing function of an aggregate's state: it applies one event to the state. A function named onSourcing needs no annotation.

It takes the event, and may take the commit the event belongs to second (me.ahoo.wow.api.read.EventStream): its commit time, operator and version, as the log records them. The kernel gives the same commit deciding and replaying, from the log or from a snapshot's tail, so a state that reads a time reads it from the commit, never from a clock, and a rebuild reads the same state:

fun onSourcing(event: OrderPaid, commit: EventStream) {
    paidAt = commit.commitTime
    paidBy = commit.operator?.id
}