```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

Im Hintergrund erstellt das `open("./somefile.txt")` ein Objekt, das als „Kontextmanager“ bezeichnet wird.

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

Под капотом" open("./somefile.txt") создаёт объект называемый "контекстным менеджером".

Когда блок `with` завершается, он обязательно закрывает файл, даже если были исключения.

例如，<a href="https://docs.python.org/zh-cn/3/tutorial/inputoutput.html#reading-and-writing-files" class="external-link" target="_blank">你可以使用`with`读取文件</a>：

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

在底层，`open("./somefile.txt")`创建了一个被称为"上下文管理器"的对象。

当 `with` 代码块结束时，它会确保关闭文件，即使发生了异常也是如此。

当你使用 `yield` 创建一个依赖项时，**FastAPI** 会在内部将其转换为上下文管理器，并与其他相关工具结合使用。

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

Underneath, the `open("./somefile.txt")` creates an object that is called a "Context Manager".

When the `with` block finishes, it makes sure to close the file, even if there were exceptions.

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

その後の`open("./somefile.txt")`は「コンテキストマネージャ」と呼ばれるオブジェクトを作成します。

`with`ブロックが終了すると、例外があったとしてもファイルを確かに閉じます。

`yield`を依存関係を作成すると、**FastAPI** は内部的にそれをコンテキストマネージャに変換し、他の関連ツールと組み合わせます。

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

Por baixo dos panos, o código `open("./somefile.txt")` cria um objeto que é chamado de "Gerenciador de Contexto".

	bufp := ODirectPoolMedium.Get().(*[]byte)
	defer ODirectPoolMedium.Put(bufp)
	buf := *bufp

	return io.CopyBuffer(writerOnly{dst}, src, buf)
}

// SameFile returns if the files are same.
func SameFile(fi1, fi2 os.FileInfo) bool {
	if !os.SameFile(fi1, fi2) {
		return false
	}
	if !fi1.ModTime().Equal(fi2.ModTime()) {
		return false
	}
	if fi1.Mode() != fi2.Mode() {
		return false
	}

	go func() {
		for {
			client.doListen(ctx, listenCh, v)
			select {
			case <-ctx.Done():
				return
			default:
				// There was error in the REST request, retry after sometime as probably the peer is down.
				time.Sleep(5 * time.Second)
			}
		}
	}()
}

// Trace - send http trace request to peer nodes

		if foundLocal || (epsResolved == len(endpoints)) {
			break
		}

		// Retry infinitely on Kubernetes and Docker swarm.
		// This is needed as the remote hosts are sometime
		// not available immediately.
		select {
		case <-globalOSSignalCh:
			return fmt.Errorf("The endpoint resolution got interrupted")
		default:
			for i, resolved := range resolvedList {
				if resolved {

pkg os, func Lstat(string) (FileInfo, error)
pkg os, func Mkdir(string, FileMode) error
pkg os, func MkdirAll(string, FileMode) error
pkg os, func OpenFile(string, int, FileMode) (*File, error)
pkg os, func SameFile(FileInfo, FileInfo) bool
pkg os, func Stat(string) (FileInfo, error)
pkg os, method (*File) Chmod(FileMode) error
pkg os, method (*File) Readdir(int) ([]FileInfo, error)
pkg os, method (*File) Stat() (FileInfo, error)