whitehead

This module contains two base classes, which distinguish between “actual occasions” (which seems to be what a “domain event” is) and “events” (which seems to be what an “aggregate” is). These terms are taken from the book Process and Reality by Alfred North Whitehead’s (published 1929).

class eventsourcing.whitehead.Event

Bases: object

“I shall use the term ‘event’ in the more general sense of a nexus of actual occasions, inter-related in some determinate fashion in one extensive quantum. An actual occasion is the limiting type of an event with only one member.”

Alfred North Whitehead, 1929

class eventsourcing.whitehead.ActualOccasion

Bases: eventsourcing.whitehead.Event

“‘Actual entities’ – also termed ‘actual occasions’ – are the final real things of which the world is made up. There is no going behind actual entities to find anything more real.”

“Just as ‘potentiality for process’ is the meaning of the more general term ‘entity’ or ‘thing’; so ‘decision’ is the additional meaning imported by the word ‘actual’ into the phrase ‘actual entity’. ‘Actuality’ is the decision amid ‘potentiality’. It represents stubborn fact which cannot be evaded.”

“Actual entities perish, but do not change; they are what they are.”

Alfred North Whitehead, 1929

class eventsourcing.whitehead.EnduringObject

Bases: eventsourcing.whitehead.Event

“The notions of ‘social order’ and of ‘personal order’ cannot be omitted from this preliminary sketch. A ‘society’ in the sense in which that term is here used, is a nexus with social order; and an ‘enduring object’ or ‘enduring creature’ is a society whose social order has taken the special form of ‘personal order.’”

“A nexus enjoys ‘personal order’ when (a) it is a ‘society’ and when the genetic relatedness of its members orders these members ‘serially’.”

Alfred North Whitehead, 1929