Implementing Domain-Driven Design

Value Characteristics

As a first order of business, make certain when modeling a domain concept as a Value Object that you are addressing the Ubiquitous Language. Consider this to be an overarching principle and a characteristic that must be achieved. I imply this principle throughout the chapter.

When you are trying to decide whether a concept is a Value, you should determine whether it possesses most of these characteristics:

• It measures, quantifies, or describes a thing in the domain.

• It can be maintained as immutable.

• It models a conceptual whole by composing related attributes as an integral unit.

• It is completely replaceable when the measurement or description changes.

• It can be compared with others using Value equality.

• It ...