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正在寻找一种更简洁的方法将C#setter放入字典中进行映射吗

reflection .net c#

Clinton Pierce · 技术社区 · 4 年前

这是一个更大的代码位的表示,我正在处理的是一个映射器。最初它被写成一个大的 switch 转换

我的第一次传球看起来像这样(来自LINQPad):

    Dictionary<string, Action<Foobar, decimal>> map
        = new Dictionary<string, Action<Foobar, decimal>> {
                { "one", (f,d) => f.One = d },
                { "double", (f,d) => f.Two = d },
                { "tricycle", (f,d) => f.Three = d },
        };
    
    void Main()
    {
        Foobar obj = new Foobar();
        decimal amount = 100M;
        var x = map["one"];
        x(obj, amount);
    
        Console.WriteLine(obj.One);   // Prints 100 as expected
    }
    public class Foobar
    {
        public decimal One { get; set; }
        public decimal Two { get; set; }
        public decimal Three { get; set; }
    }

Foobar decimal .

{ "one", (f,d) => f.One = d },          // It works, but â¦ can it be better?

不希望在调用中作为字符串进行完全反射:

{ "one", "One" },                       // No
{ "one", nameof(Foobar.One) },          // Really, just no.

我似乎记得有一种更简洁的方法可以做到这一点,但我的googlefu让我失望了。我可以去 吸气剂 通过将签名改为 Dictionary<string, Func<Foobar, decimal>>

   { "one", f.One }                        // The getter, not the setter.

但这不能让我去 . 思想?

0 回复 | 直到 4 年前

Blindy 4 年前

您可以这样定义映射:

Mapping<Foobar, decimal> foobarMapping = new Mapping<Foobar, decimal> 
{
    { "one", f => f.One },
    { "double", f => f.Two },
    { "tricycle", f => f.Three },
};

public class Foobar
{
    public decimal One { get; set; }
    public decimal Two { get; set; }
    public decimal Three { get; set; }
}

void Main()
{
    Foobar obj = new Foobar();
    obj.One = 100M;
    
    foobarMapping[obj, "one"].Dump();
    
    foobarMapping[obj, "tricycle"] = 400M;
    obj.Three.Dump();
}

class Mapping<TFrom, TTo>: IEnumerable<KeyValuePair<string, PropertyInfo>>
{
    Dictionary<string, PropertyInfo> mapping = new Dictionary<string, PropertyInfo>();
    
    public void Add(string name, Expression<Func<TFrom, TTo>> mappingFunction) =>
        mapping.Add(name, (PropertyInfo)((MemberExpression)mappingFunction.Body).Member);
        
    public TTo this[TFrom from, string key]
    {
        get => (TTo)mapping[key].GetValue(from);
        set => mapping[key].SetValue(from, value);
    }
        
    public IEnumerator<KeyValuePair<string, PropertyInfo>> GetEnumerator() =>
        mapping.GetEnumerator();

    IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
}

如预期,哪些产出:

100
400