C# Linq问题

Question

LINQ 是否有序列运算符，允许对每个元素执行某些操作而不将其投影到新序列？

这可能看起来有点尴尬，但只是为了让我知道 :)

例子:

IEnumerable<IDisposable> x;
x.PERFORM_ACTION_ON_EVERY_ELEMENT(m => m.Dispose());

显然，这可以使用类似的东西来完成:

foreach (var element in x) x.Dispose();

但如果某些东西确实存在，那就太好了。

Answer 1

不，它不存在。特别是出于您提到的原因:拥有一个行为与所有其他人完全不同的运算符(operator)似乎很尴尬。

Eric Lippert，C# 编译器开发人员之一 has an article关于这个。

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 purpose of an expression is to compute a value, not to cause a side effect. The purpose of a statement is to cause a side effect. The call site of this thing would look an awful lot like an expression (though, admittedly, since the method is void-returning, the expression could only be used in a “statement expression” context.)

It does not sit well with me to make the one and only sequence operator that is only useful for its side effects.