IEnumerable T空合并扩展 [英] IEnumerable<T> null coalescing Extension

问题描述

在通过foreach或LINQ查询遍历IEnumerable<T>之前，我经常遇到检查IEnumerable<T>是否为空的问题，然后我经常遇到这样的代码:

I frequently face the problem to check whether an IEnumerable<T> is null before iterating over it through foreach or LINQ queries, then I often come into codes like this:

var myProjection = (myList ?? Enumerable.Empty<T>()).Select(x => x.Foo)...

因此，我想将此扩展方法添加到Extensions类:

Hence, I thought to add this extension-method to an Extensions class:

public static class MyExtensions 
{
    public static IEnumerable<T> AsEmptyIfNull<T>(this IEnumerable<T> source)
    {
        return source ?? Enumerable.Empty<T>();
    }
}

我很快就想到了一个小问题，即考虑到扩展方法的实例方法方面" ，应该将其实现为纯粹的静态方法，否则这样完全合法:

A little issue comes immediately in my mind looking at this code, i.e., given the "instance-methods aspect" of extension-methods, it should be implemented as a mere static method, otherwise something like this would be perfectly legal:

IEnumerable<int> list = null;
list.AsEmptyIfNull();

使用它是否还有其他缺点?
如果大量使用，这种扩展会导致开发人员出现某种不良趋势吗?

Do you see any other drawback in using it ?
Can such extension leading to some kind of bad-trend in the developer(s), if massively used?

奖励问题:

您能建议一个更好的名字吗? :)
(英语不是我的母语，所以我的名字不太好...)

Can you suggest a better name to it ? :)
(English is not my first language, then I'm not so good in naming...)

谢谢.

推荐答案

返回IEnumerable<T>的方法应返回一个空值，而不是null.这样您就不需要了.

Methods that return an IEnumerable<T> should return an empty one, instead of null. So you wouldn't need this.

查看此问题:返回null还是返回更好?空集合?

否则，您的代码就可以了.

Otherwise, your code seems ok.

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