Also from Ward Cunningham is the CHECKS Pattern Language (published as far back as 1994), which developed novel ideas about value objects well beyond the mainst

Also from Ward Cunningham is the CHECKS Pattern Language (published as far back as 1994), which developed novel ideas about value objects well beyond the mainstream of the day. The examples are in Smalltalk but the uniform abstraction level for values is an instantly applicable concept, allowing generic treatment of value objects, and is probably more accessible to modern audiences comfortable with option types and so on than it was at the time. http://c2.com/ppr/checks.html http://c2.com/ppr/checks.html