c# - 可以使子类仅通过静态属性实例化

Question

假设我有以下类(class):

public class Gender
{
    public readonly string Name { get; set;}
    public readonly char Abbreviation { get; set;} 
    public readonly string ChildName { get; set;}
    public readonly int Number { get; set;}

    public static Gender Male = new Gender { Name = "Male", Abbreviation = 'M', Number = 1, ChildName = "Boy" };
    public static Gender Female = new Gender { Name = "Female", Abbreviation = 'F', Number = 2, ChildName = "Girl" };
    public static Gender Unknown = new Gender { Name = "Unknown", Abbreviation = 'U', Number = 0, ChildName = "Unknown" };
}

我怎样才能使通过除此之外的任何其他方式实例化 Gender 类成为非法

性别 MyGender = Gender.Male

因此制作

Gender Spaghetti = new Gender{Name = "Spaghetti", Abbreviation = 'S', Number = 123, ChildName = "Angel Hair" }

在编译时抛出错误？

Answer 1

将 private 构造函数添加到 Gender 类:

public class Gender
{
    public readonly string Name { get; set;}
    public readonly char Abbreviation { get; set;} 
    public readonly string ChildName { get; set;}
    public readonly int Number { get; set;}

    private Gender()
    {
    }

    public static Gender Male = new Gender { Name = "Male", Abbreviation = 'M', Number = 1, ChildName = "Boy" };
    public static Gender Female = new Gender { Name = "Female", Abbreviation = 'F', Number = 2, ChildName = "Girl" };
    public static Gender Unknown = new Gender { Name = "Unknown", Abbreviation = 'U', Number = 0, ChildName = "Unknown" };
}

您也可以将 readonly 添加到 Male/Female/Unknown 声明中，以使以下代码不可能:

Gender.Male = Gender.Female;