c# – 为什么只有ForEach方法的列表

从我可以看到,ForEach方法仅适用于列表 class.

这是为什么？我可以看到没有任何理由ForEach不可用于实现IEnumerable / IEnumerator接口的任何类,如果您需要执行一个小动作(1行比1行2样板Foreach语法更可读),这是一个非常有用的方法. ..).

更新：我会澄清我的问题.包含ForEach的序列有完全有效的原因.没有包括所有序列的完美的理由.

但是我不明白为什么ForEach只能包含在一些序列中.

解决方法

见Eric Lippert的帖子： “foreach” vs “ForEach”

A number of people have asked me why
there is no Microsoft-provided
“ForEach” sequence operator extension
method. The List class has such a
method already of course,but there’s
no reason why such a method Could not
be created as an extension method for
all sequences.

…

But we can go a bit deeper here. I am
philosophically opposed to providing
such a method,for two reasons.

…

The first reason is that doing so
violates the functional programming
principles that all the other sequence
operators are based upon. Clearly the
sole purpose of a call to this method
is to cause side effects.

…

The second reason is that doing so
adds zero new representational power
to the language.

…

Well,the VS Languages team does not have any influence on what goes into List. I personally find the “ForEach” method on List philosophically troubling for all the same reasons that I would find an extension method on IEnumerable troubling. (And the VSL team does control that.) The one mitigating factor is that List is clearly designed to be a mutable,not-side-effect-free data structure,so using expressions that mutate it seems slightly less bad. — Eric

原文地址：https://www.jb51.cc/csharp/96422.html