C# 7.0 開始支援 Throw expressions。

三元運算中可以視需要直接丟出 exception。

...
this.FirstName = firstName == null ? throw new ArgumentNullException(nameof(firstName)) : firstName;
...

?? 運算式中也可以直接丟出 exception。

...
this.LastName = lastName ?? throw new ArgumentNullException(nameof(lastName));
...

Expression bodied member 也可以丟出 exception。

...
public override string ToString() => throw new NotImplementedException();
...

最後附上完整的測試範例：

class Program
{
static void Main(string[] args)
{
var person = new Person("Larry", "Nung");
Console.WriteLine(person.ToString());
}
}
struct Person
{
public string FirstName { get; set; }
public string LastName { get; set; }

public Person(string firstName, string lastName)
{
this.FirstName = firstName == null ? throw new ArgumentNullException(nameof(firstName)) : firstName;
this.LastName = lastName ?? throw new ArgumentNullException(nameof(lastName));
}

public override string ToString() => throw new NotImplementedException();
}

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