我是否需要考虑任何的IEnumerable&LT处置; T>我用？ [英] Do I need to consider disposing of any IEnumerable<T> I use?

问题描述

它最近已经向我指出的各种LINQ的扩展方法（如其中，，选择等）返回的IEnumerable< T> 这也恰好是的IDisposable 。下面的计算结果为真

It's recently been pointed out to me that various Linq extension methods (such as Where, Select, etc) return an IEnumerable<T> that also happens to be IDisposable. The following evaluates to True

new int[2] {0,1}.Select(x => x*2) is IDisposable

我是否需要处置一个其中，表达式的结果？

Do I need to dispose of the results of a Where expression?

每当我打电话回的IEnumerable℃的方法; T> ，我是（可能）承担责任调用处理时，我用它完成了吗？

Whenever I call a method returning IEnumerable<T>, am I (potentially) accepting responsibility for calling dispose when I've finished with it?

推荐答案

没有，你不必担心这一点。

No, you don't need to worry about this.

他们返回的IDisposable 执行情况的事实是一个实现细节 - 这是因为微软执行的C＃编译器的迭代器块发生创建的单它实现类型都的IEnumerable< T> 和的IEnumerator< T> 。 ，后者扩展的IDisposable ，这就是为什么你看到它

The fact that they return an IDisposable implementation is an implementation detail - it's because iterator blocks in the Microsoft implementation of the C# compiler happen to create a single type which implements both IEnumerable<T> and IEnumerator<T>. The latter extends IDisposable, which is why you're seeing it.

示例代码来演示这一点：

Sample code to demonstrate this:

using System;
using System.Collections.Generic;

public class Test 
{
    static void Main() 
    {
        IEnumerable<int> foo = Foo();
        Console.WriteLine(foo is IDisposable); // Prints True
    }

    static IEnumerable<int> Foo()
    {
        yield break;
    }
}

请注意，您的做的需要采取的事实，即的IEnumerator<注; T> 工具的IDisposable 。所以，你明确地迭代任何时候，你应该妥善处置。例如，如果你想遍历的东西，并确保您始终的在的值，可以使用这样的：

Note that you do need to take note of the fact that IEnumerator<T> implements IDisposable. So any time you iterate explicitly, you should dispose of it properly. For example, if you want to iterate over something and be sure that you'll always have a value, you might use something like:

using (var enumerator = enumerable.GetEnumerator())
{
    if (!enumerator.MoveNext())
    {
        throw // some kind of exception;
    }
    var value = enumerator.Current;
    while (enumerator.MoveNext())
    {
        // Do something with value and enumerator.Current
    }
}

（A 的foreach 循环会自动做到这一点，当然）。

(A foreach loop will do this automatically, of course.)

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