为什么 IEnumerable 上没有 ForEach 扩展方法? [英] Why is there no ForEach extension method on IEnumerable?

问题描述

受到另一个关于缺少 Zip 函数的问题的启发:

Inspired by another question asking about the missing Zip function:

为什么IEnumerable 接口上没有ForEach 扩展方法?或者任何地方?获得 ForEach 方法的唯一类是 List<>.是否有丢失的原因，也许是性能?

Why is there no ForEach extension method on the IEnumerable interface? Or anywhere? The only class that gets a ForEach method is List<>. Is there a reason why it's missing, maybe performance?

推荐答案

在大多数情况下，该语言中已经包含了一个 foreach 语句.

There is already a foreach statement included in the language that does the job most of the time.

我不想看到以下内容:

list.ForEach( item =>
{
    item.DoSomething();
} );

代替:

foreach(Item item in list)
{
     item.DoSomething();
}

后者更清晰、更易于阅读在大多数情况下，尽管键入时间可能会更长一些.

The latter is clearer and easier to read in most situations, although maybe a bit longer to type.

但是，我必须承认我在这个问题上改变了立场；ForEach() 扩展方法在某些情况下确实很有用.

However, I must admit I changed my stance on that issue; a ForEach() extension method would indeed be useful in some situations.

以下是语句和方法之间的主要区别:

Here are the major differences between the statement and the method:

• 类型检查:foreach 在运行时完成，ForEach() 在编译时(大加分！)
• 调用委托的语法确实要简单得多:objects.ForEach(DoSomething);
• ForEach() 可以被链接起来:尽管这样一个功能的邪恶/有用性是可以讨论的.

• Type checking: foreach is done at runtime, ForEach() is at compile time (Big Plus!)
• The syntax to call a delegate is indeed much simpler: objects.ForEach(DoSomething);
• ForEach() could be chained: although evilness/usefulness of such a feature is open to discussion.

这些都是这里很多人提出的重要观点，我可以理解为什么人们缺少该功能.我不介意微软在下一次框架迭代中添加一个标准的 ForEach 方法.

Those are all great points made by many people here and I can see why people are missing the function. I wouldn't mind Microsoft adding a standard ForEach method in the next framework iteration.

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