如何轻松地从lambda函数创建比较器? [英] How to create a Comparer from a lambda function easily?

问题描述

我想知道.Net框架中是否提供了一个实现IComparer的类，并且可以从lambda函数构造它.这样做会很有用:

I am wondering if there was a class provided in the .Net framework that implements IComparer and that can be constructed from a lambda function. That would be useful to be able to do:

void SortByLength(List<string> t)
{
    t = t.OrderBy(
           s => s, 
           Comparer<string>.FromLambda((s1,s2) => s1.Length.CompareTo(s2.Length))
        ).ToList();
}

比每次都定义一个Comparer类要容易得多.我知道创建这样的FromLambda方法并不复杂，但是我想知道框架中是否存在现有的方法，因为我认为这是一个非常常见的功能.

It would be much easier than having to define a Comparer class each time. I know it is not complicated to create such a FromLambda method, but I was wondering if there was an existing way in the framework as I see this as being a pretty common feature.

推荐答案

为什么要这么难?

按长度排序列表很简单:

Ordering the list by length is as simple as:

var ordered = list.OrderBy(s => s.Length);

如果您真的需要那些复杂的东西，则可以使用CompareComparer可以帮助您.请在此处查看:将比较结果转换为icomparer

If you really need that complicated stuff, the ComparisonComparer could help you out. Please have a look here: Converting Comparison to icomparer

这是从lamda或委托中构建IComparer！

This is building an IComparer from a lamda or delegate!

这是该示例中的基本代码

Here is the essential code from that example

public class ComparisonComparer<T> : IComparer<T>  
{  
    private readonly Comparison<T> _comparison;  

    public ComparisonComparer(Comparison<T> comparison)  
    {  
        _comparison = comparison;  
    }  

    public int Compare(T x, T y)  
    {  
        return _comparison(x, y);  
    }  
}  

这篇关于如何轻松地从lambda函数创建比较器?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！