[jdlshore]

Changing ints to UUIDs is a classic example of the Primitive Obsession smell, and the solution is to wrap primitives in a type representing their semantic meaning, such as “ID,” or “PrimaryKey,” not to use a factory. That way, when you need to change the underlying type from int to UUID, you only need to do it in one place.

[shock]

Indeed. Unfortunately, in some languages – like Java or C#, it is harder to do without incurring a significant cost (boxing/unboxing) than in languages that allow type aliases/typedefs.

[jdlshore]

In theory, yes, but in practice performance is dominated by network and (less often) algorithms. The cost of boxing/unboxing doesn’t even register except in rare cases, which can be specifically coded for.