Unsigned number instead of checking invariant in DDD

Question

If you know a number cannot be negative, which design is better in a DDD model?

public record Quantity(uint Number);

public record Quantity()
{
    public int number { get; init; }
    public Quantity(int number)
    {
        if (number < 0) throw new ArgumentOutOfRangeException("Quantity must be positive");
    }
}

Answer 1

If you know a number cannot be negative, which design is better in a DDD model ?

I can't think of a single DDD example I have seen that uses unsigned types as a general purpose data structure.

The general rule for unsigned types is that you use default to using a signed type, and use unsigned types only when appropriate to the specific task at hand.

Google C++ Style Guide

Do not use an unsigned type merely to assert that a variable is non-negative.

CPP Core Guidelines: ES106

Don't try to avoid negative values by using unsigned

Stroustrup, Sutter and Carruth were of unanimous opinion in 2013

• Video
• Transcript courtesy of Nayuki (near bottom of page)

Online discussions that agree with the above

• Jacob Egner
• Chris Cannam