Immutable Domain Types example

immutable-domain-types-example.cs

public record Contact
{
    public required PersonalName Name { get; init; }
    public required EmailAddress Email { get; init; }
}

public record PersonalName
{
    public required string First
    {
        get => _first;
        init => _first = ValidateName(value, nameof(First));
    }

    public required string Last
    {
        get => _last;
        init => _last = ValidateName(value, nameof(Last));
    }

    private readonly string _first = "";
    private readonly string _last = "";

    private static string ValidateName(string name, string argument = "")
    {
        string value = name?.Trim() ?? "";
        bool ok = value.Length > 1 && value.Length < 80;
        if (!ok) throw new ArgumentOutOfRangeException(argument);
        return value;
    }
}

public record EmailAddress
{
    public string Value => _value;

    public EmailAddress(string value)
    {
        _value = value?.Trim() ?? "";
        if (!_regex.IsMatch(_value)) throw new ArgumentException("invalid email format");
    }

    private readonly string _value = "";
    private static readonly Regex _regex = 
        new(@"^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$");
}