When To Wrap Primitives

Wrap primitives when the wrapper changes correctness, not when it only signals virtue.

Wrap When

• The value has a domain name and invariant.

• Two values of the same primitive type can be confused.

• Validation is repeated or easy to forget.

• Behavior naturally belongs with the value.

• Invalid states cause meaningful business risk.

Do Not Wrap Yet When

• The value has no behavior or invariant.