是否可以在枚举中保存一个Type（使用“typeof（）”）？ [英] Is it possible to save a Type (using "typeof()") in an enum?

问题描述

所以我在XNA，C＃4.0中创建一个游戏，我需要管理大量的PowerUps（代码中都是继承自PowerUp类），并且处理PowerUps I的后端管理当前有一个枚举，PowerupEffectType，具有PowerUp的每个子类的值。最终在代码中，我需要从PowerupEffectType转换为Powerup类型（类 Type ，通常使用 typeof（[class name]））。

由于这是一个组项目，我想要将PowerupEffectType的每个值与其相应的类类型结合起来，也就是：不只是期望我的其他程序员使用switch语句来手动进行转换，并且确保添加/扩展稍后在尽可能少的地方涉及少量更改。我有几个选择，迄今为止我发现的最好的是创建枚举伪方法，将所有内容都集中到一个switch语句（我想要的99％），感谢我在这里找到的一些提示： a href =http://msdn.microsoft.com/en-us/library/bb383974.aspx =noreferrer> http://msdn.microsoft.com/en-us/library/bb383974.aspx

但是我想再进一步 - 我可以保存一个类型在枚举？我知道您可以将枚举作为特定类型保存（链接： http://msdn.microsoft.com/en-us/library/cc138362.aspx ），但 Type 不是其中之一。当前的选择是字节，字节，短，ushort，int，uint，long和ulong 。有没有可行的方式来保存转换为类型到任何上述数据类型，并返回？

<强>要清楚，这就是我可以做的事情，我正在寻找一种方法：

  //（假设LightningPowerup，FirePowerup和WaterPowerup是
 //所有声明的类继承自单个基类）
 
 public enum PowerupEffectType 
 {
 LIGHTNING = typeof（LightningPowerup），
 FIRE = typeof（FirePowerup），
 WATER = typeof（WaterPowerup）
} 
  

有没有办法做到这一点，或者我只是解决了已经99％完成的问题的解决方案？

提前感谢

解决方案

你不能像值，但您可以在属性中指定：

 使用系统; 
使用System.Runtime.CompilerServices; 
 
 [AttributeUsage（AttributeTargets.Field）] 
 public class EffectTypeAttribute：Attribute 
 {
 public Type Type {get;私人集合
 
 public EffectTypeAttribute（Type type）
 {
 this.Type = type; 
} 
} 
 
 public class LightningPowerup {} 
 public class FirePowerup {} 
 public class WaterPowerup {} 
 
 public枚举PowerupEffectType 
 {
 [EffectType（typeof（LightningPowerup））] 
闪电，
 [EffectType（typeof（FirePowerup））] 
 Fire，
 [ EffectType（typeof（WaterPowerup））] 
水
} 
  

通过反射在执行时提取这些属性值。但是，我会个人只需创建一个字典：

  private static Dictionary< PowerupEffectType，Type> EffectTypeMapping = 
 new Dictionary< PowerupEffectType，Type> 
 {
 {PowerupEffectType.Lightning，typeof（LightningPowerup）}，
 {PowerupEffectType.Fire，typeof（FirePowerup）}，
 {PowerupEffectType.Water，typeof（WaterPowerup）} 
}; 
  

无需特殊属性，无需使用虚拟反思代码提取值。

So I'm creating a game in XNA, C# 4.0, and I need to manage a lot of PowerUps (which in code are all inherited from class "PowerUp"), and to handle back-end management of the PowerUps I currently have an enum, PowerupEffectType, with a value for each child class of PowerUp. Eventually in the code I need to do conversions from PowerupEffectType to the Powerup type (of class Type, achieved usually with typeof([class name])).

Since this is a group project, I want to marry each value of PowerupEffectType to its corresponding class Type as well as possible, i.e.: Not just expect my other programmers to use switch statements to do the conversion manually, and making sure additions/expansions later involve as few changes in as few places as possible. I have a few options for this, and the best I've discovered so far is creating enum pseudo-methods that condense everything down to a single switch statement (99% of what I want), thanks to some tips I found here: http://msdn.microsoft.com/en-us/library/bb383974.aspx

But I'm trying to take it one step further - can I save a Type in an enum? I know you can save enums as a specific type (link: http://msdn.microsoft.com/en-us/library/cc138362.aspx), but Type isn't one of them. The current choices are byte, sbyte, short, ushort, int, uint, long, and ulong. Is there any feasible way to save a convert a Type to any of the above data types and back?

Just to be clear, this is what I WISH I could do, and I'm looking for a way to do:

// (Assuming 'LightningPowerup', 'FirePowerup', and 'WaterPowerup' are
// all declared classes that inherit from a single base class)

public enum PowerupEffectType
{
    LIGHTNING = typeof(LightningPowerup),
    FIRE = typeof(FirePowerup),
    WATER = typeof(WaterPowerup)
}

Is there any way to do this, or am I just overcomplicating a solution to a problem that's already 99% complete?

Thanks in advance!

解决方案

You can't do it as the value of an enum, but you could specify it in an attribute:

using System;
using System.Runtime.CompilerServices;

[AttributeUsage(AttributeTargets.Field)]
public class EffectTypeAttribute : Attribute
{
    public Type Type { get; private set; }

    public EffectTypeAttribute(Type type)
    {
        this.Type = type;
    }
}

public class LightningPowerup {}
public class FirePowerup {}
public class WaterPowerup {}

public enum PowerupEffectType
{
    [EffectType(typeof(LightningPowerup))]
    Lightning,
    [EffectType(typeof(FirePowerup))]
    Fire,
    [EffectType(typeof(WaterPowerup))]
    Water
}

You can then extract those attribute values at execution time with reflection. However, I would personally just create a dictionary:

private static Dictionary<PowerupEffectType, Type> EffectTypeMapping =
    new Dictionary<PowerupEffectType, Type>
{
    { PowerupEffectType.Lightning, typeof(LightningPowerup) },
    { PowerupEffectType.Fire, typeof(FirePowerup) },
    { PowerupEffectType.Water, typeof(WaterPowerup) }
};

No need for a special attribute, no need to extract the values with fiddly reflection code.

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