如何离开lambda表达式的身体 [英] How to leave the body of a lambda expression

问题描述

我有一些名单，我 list.ForEach（L => {...什么...}）。现在，在一定条件下我需要停下来遍历列表，但破不工作 - 我得到控制不能离开的身体匿名方法或lambda表达式编译错误。

I have some list and I do list.ForEach( l => { ... something ...}). Now, on certain condition I need to stop iterating over the list, but break doesn't work - I get "Control cannot leave the body of an anonymous method or lambda expression" compilation error.

不知道如何克服这个限制？

Any idea how to overcome that restriction?

推荐答案

使用破因为拉姆达比for循环不同的方法执行本身不会在这里工作。 A 破语句仅用于构建本地的当前功能的突破是有用的。

Using break alone won't work here because the lambda executes in a different method than the for loop. A break statement is only useful for breaking out of constructs local to the current function.

为了支持断点风格离开你需要添加的ForEach ，其中代理可过载通过返回值，循环执行要打破规定。例如：

In order to support a break style leave you'd need to add an overload of ForEach where the delegate can specify via a return value that loop execution should break. For example

public static void ForEach<T>(this IEnumerable<T> enumerable, Func<T, bool> func) {
  foreach (var cur in enumerable) {
    if (!func(cur)) {
      break;
    }
  }
}

现在的这种消费的ForEach 方法可以通过返回假从所提供的指定破回调

Now a consumer of this ForEach method can specify a break by returning false from the provided callback

myCollection.ForEach(current => {
  if (someCondition) {
    // Need to break
    return false;
  }
  // Keep going
  return true;
}

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