如何检查 IEnumerable 是 null 还是空? [英] How to check if IEnumerable is null or empty?

问题描述

我喜欢 string.IsNullOrEmpty 方法.我很想拥有一些可以为 IEnumerable 提供相同功能的东西.有这样的吗?也许一些收集助手类?我问的原因是，在 if 语句中，如果模式是 (mylist != null && mylist.Any())，代码看起来很混乱.使用 Foo.IsAny(myList) 会更简洁.

I love string.IsNullOrEmpty method. I'd love to have something that would allow the same functionality for IEnumerable. Is there such? Maybe some collection helper class? The reason I am asking is that in if statements the code looks cluttered if the patter is (mylist != null && mylist.Any()). It would be much cleaner to have Foo.IsAny(myList).

这篇文章没有给出答案:IEnumerable 是空的?.

This post doesn't give that answer: IEnumerable is empty?.

推荐答案

当然你可以写:

public static class Utils {
    public static bool IsAny<T>(this IEnumerable<T> data) {
        return data != null && data.Any();
    }
}

但是，请注意并非所有序列都是可重复的；通常我更喜欢只走一次，以防万一.

however, be cautious that not all sequences are repeatable; generally I prefer to only walk them once, just in case.

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