是否可以基于同级类属性 C# 添加计算属性？

Question

我有一个类型的类：

public class sample
{
    public int id;
    public string s;
    //Need a calculative property based on sibling value
    //Ex. public float CharRatio
}

考虑以下数据集

List<sample> s = new List<sample>();
s.Add(new sample{id = 1, s = "source"}); //id 1 is always source charRatio 100 since 6/6 in percentage
s.Add(new sample{id = 2, s = "test"}); //charRatio = 66
s.Add(new sample{id = 3, s = "test"}); //charRatio = 66
s.Add(new sample{id = 4, s = "test"}); //charRatio = 66

是否可以向类添加一个计算属性，该属性将使用 LINQ/LAMBDA 或任何解决方法根据集合中兄弟的值计算值。 我正在尝试找到一种方法来添加使用以下方法计算的 charRatio：

charRatio = source.Len/test.Len

源使用 ID 标识，该 ID 始终为 1。 我的要求需要它是一个计算属性，以便我可以在表达式树中使用它。

Answer 1

这是一个属性，其值是根据给定的属性/值计算的。我希望我能正确理解您的要求。让我知道它是否不符合您的需要。我也尝试写尽可能多的 cmets。所以让代码来说话吧:)

public class Sample {

    /// <summary>
    /// This sourcestring is set to the same value of Sample with Id = 1
    /// </summary>
    private string _sourceStringOfSampleWithId1;

    /// <summary>
    /// Creates a Sample instance
    /// </summary>
    /// <param name="id">Id of Sample</param>
    /// <param name="source">Source of Sample</param>
    public Sample(int id, string source) {
        Id = id;
        Source = Source;
    }

    /// <summary>
    /// Id of Sample
    /// </summary>
    public int Id { get; }
    
    /// <summary>
    /// Source of Sample
    /// </summary>
    public string Source { get; }
    
    /// <summary>
    /// Calculative property for CharRatio
    /// </summary>
    public double CharRatio => (double)_sourceStringOfSampleWithId1.Length / Source.Length * 100;

    /// <summary>
    /// Sets SourceString of Sample with Id = 1
    /// </summary>
    /// <param name="sourceString"></param>
    public void SetSourceString(string sourceString) {
        _sourceStringOfSampleWithId1 = sourceString;
    }

}

这是你如何使用它：

List<Sample> sampleList = new List<Sample>(); // Creates a sample list
sampleList.Add(new Sample(1, "source")); //id 1 is always source charRatio 100 since 6/6 in percentage
sampleList.Add(new Sample(2, "test")); //charRatio = 66
sampleList.Add(new Sample(3, "test")); //charRatio = 66
sampleList.Add(new Sample(4, "test")); //charRatio = 66
var sampleWithId1 = sampleList.Find(s=>s.Id == 1); // Find sample with Id = 1
sampleList.ForEach(s=>s.SetSourceString(sampleWithId1.Source)); // Set all samples calcualtive source string to Sample with Id =1
var ratio = sampleList[2].CharRatio; //66.66; // Get an example from list and see char ratio

基于 cmets，这里是 Sample 类的编辑版本。我也保留原来的答案。因此，请使用适合您的用例的任何一个。我不会评论这种情况，因为从原始答案中应该很明显。

public class SampleWithStaticField {

    private static string _sourceStringOfSampleWithId1;
    public SampleWithStaticField(int id, string source) {
       Id = id;
       Source = Source;
       // Set static source string which will be shared between all instances
        if(Id == 1) {
            _sourceStringOfSampleWithId1 = source;
       }
    }
    public int Id { get; }
    public string Source { get; }
    public double CharRatio {
        get {
            if(_sourceStringOfSampleWithId1 == null) {
                throw new Exception($"{nameof(_sourceStringOfSampleWithId1)} is not set!");
            }
            return (double)_sourceStringOfSampleWithId1.Length / Source.Length * 100;
        }
    }
}

这里是你如何使用它

var sampleList = new List<Sample>();
sampleList.Add(new Sample(1, "source")); //id 1 is always source charRatio 100 since 6/6 in percentage
sampleList.Add(new Sample(2, "test")); //charRatio = 66
sampleList.Add(new Sample(3, "test")); //charRatio = 66
sampleList.Add(new Sample(4, "test")); //charRatio = 66
var ratio = sampleList[2].CharRatio; //66.66;

Answer 2

如果列表的id = 1 始终是源的基础并且它是UNIQUE

，我的方法是这样的

public class sample
{
    public int id {get; set;
    public string s {get; set;}
    public float ratio {get; set;}
}


var list = new List<sample>();
//same values you listed
//...
//...

然后我会通过foreach 来添加比率

var sourceObject = list.First(x => x.Id == 1);
var result = list.ForEach(x => {
    
   if (x.Id == sourceObject.Id)
   {
       x.ratio = 1;
   }
   else
   {
       x.ratio = x.s.Length/sourceObject.Length * 100
   }
    
});