多个枚举说明

Question

我已经定义了以下内容enum:

public enum DeviceType
{
    [Description("Set Top Box")]
    Stb = 1,
    Panel = 2,
    Monitor = 3,
    [Description("Wireless Keyboard")]
    WirelessKeyboard = 4
}

我正在利用该Description属性允许我提取更多用户可读的枚举版本以在UI中显示.我使用以下代码获得描述:

var fieldInfo = DeviceType.Stb.GetType().GetField(DeviceType.Stb.ToString());

var attributes = (DescriptionAttribute[])fieldInfo.GetCustomAttributes(typeof(DescriptionAttribute), false);

var description = (attributes.Length > 0 ? attributes[0].Description : DeviceType.Stb.ToString());

上面的代码将给我:description = "Set Top Box".如果没有Description设置属性,它将为我提供枚举的字符串值.

我现在想为每个枚举添加第二个/自定义属性(为了示例,称为"值").例如:

public enum DeviceType
{
    [Description("Set Top Box")]
    [Value("19.95")]
    Stb = 1,
    [Value("99")]
    Panel = 2,
    [Value("199.99")]
    Monitor = 3,
    [Description("Wireless Keyboard")]
    [Value("20")]
    WirelessKeyboard = 4
}

我需要提取新Value属性,就像我目前使用Description属性一样.

是否可以将现有Description属性扩展为以某种方式包含新Value属性,还是最好分别创建新属性？

Answer 1

创建一个单独称为DeviceInformation的新属性...

[AttributeUsage(AttributeTargets.All)]
public class DeviceInformationAttribute : DescriptionAttribute
{
    public DeviceInformationAttribute(string description, string value)
    {
        this.Description = description;
        this.Value = value;
    }

    public string Description { get; set; }
    public string Value { get; set; }
}

您还可以使用扩展方法来检索任何属性的值

static void Main(string[] args)
{
    var info = DeviceType.Stb.GetAttribute<DeviceInformationAttribute>();
    Console.WriteLine("Description: {0}\nValue:{1}",info.Description, info.Value);

}

public static class Extensions
{
    public static TAttribute GetAttribute<TAttribute>(this Enum enumValue)
            where TAttribute : Attribute
    {
        return enumValue.GetType()
                        .GetMember(enumValue.ToString())
                        .First()
                        .GetCustomAttribute<TAttribute>();
    }
}

public enum DeviceType
{
    [DeviceInformation("foobar", "100")]
    Stb = 1,
}

编辑

回应评论

@Aydin Adn我喜欢使用扩展方法,非常好!您是否有针对DeviceType.Panel案例的解决方案,该解决方案没有描述,但需要Value属性？(见Patrick的回答评论)

 [AttributeUsage(AttributeTargets.All)]
public class DeviceInformationAttribute : Attribute
{
    public DeviceInformationAttribute(string description)
    {
        this.Description = description;
    }

    public DeviceInformationAttribute(decimal value)
    {
        this.Description = string.Empty;
        this.Value = value;
    }

    public DeviceInformationAttribute(string description, decimal value)
    {
        this.Description = description;
        this.Value = value;
    }


    public string Description { get; set; }
    public decimal Value { get; set; }
}

Answer 2

是的,这很容易做到.只需派生现有的DescriptionAttribute类:

[AttributeUsageAttribute(AttributeTargets.All)]
public class DescriptionWithValueAttribute : DescriptionAttribute
{
    public DescriptionWithValueAttribute(string description, string value) : base(description)
    {
        this.Value = value;
    }

    public string Value { get; private set; }
}

然后你可以像这样使用它:

public enum DeviceType
{
    [DescriptionWithValue("Set Top Box", "19.95")]
    Stb = 1,
}

检索属性的代码将保持几乎相同,只需替换类型名称即可.