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。

### `yield`を持つ依存関係でのコンテキストマネージャの使用

/// warning | 注意

これは多かれ少なかれ、「高度な」発想です。

**FastAPI** を使い始めたばかりの方は、とりあえずスキップした方がよいかもしれません。

///

   * iterable}. The iterator's {@code hasNext()} method returns {@code true} until {@code iterable}
   * is empty.
   *
   * <p><b>Warning:</b> Typical uses of the resulting iterator may produce an infinite loop. You
   * should use an explicit {@code break} or be certain that you will eventually remove all the
   * elements.
   */

build:android --define=with_xla_support=false
build:ios     --define=with_xla_support=false

# BEGIN TF REMOTE BUILD EXECUTION OPTIONS
# Options when using remote execution
# WARNING: THESE OPTIONS WONT WORK IF YOU DO NOT HAVE PROPER AUTHENTICATION AND PERMISSIONS

# Allow creation of resultstore URLs for any bazel invocation
build:resultstore --google_default_credentials

									title="<la:message key="labels.development_mode_warning" />"
								><a class="nav-link active" href="${installationLink}" target="_olh"><em
										class="fa fa-exclamation-triangle text-warning"
									></a></li>
							</c:if>
							<c:choose>
								<c:when test="${!empty username && username != 'guest'}">
									<li class="nav-item">
										<div class="dropdown">

   *
   * <p>Note however that if your escaper does not escape characters in the supplementary range, you
   * should either continue to validate the correctness of any surrogate characters encountered or
   * provide a clear warning to users that your escaper does not validate its input.
   *
   * <p>See {@link com.google.common.net.PercentEscaper} for an example.
   *
   * @param csq a sequence of characters

   *
   * <p>Note however that if your escaper does not escape characters in the supplementary range, you
   * should either continue to validate the correctness of any surrogate characters encountered or
   * provide a clear warning to users that your escaper does not validate its input.
   *
   * <p>See {@link com.google.common.net.PercentEscaper} for an example.
   *
   * @param csq a sequence of characters

        }

        try {
            "".getBytes(DEFAULT_OEM_ENCODING);
        } catch (final UnsupportedEncodingException uee) {
            if (LogStream.level >= 2) {
                log.println("WARNING: The default OEM encoding " + DEFAULT_OEM_ENCODING
                        + " does not appear to be supported by this JRE. The default encoding will be US-ASCII.");
            }
            DEFAULT_OEM_ENCODING = "US-ASCII";

## Opiniões

"*[...] Estou usando **FastAPI** muito esses dias. [...] Estou na verdade planejando utilizar ele em todos os times de **serviços _Machine Learning_ na Microsoft**. Alguns deles estão sendo integrados no _core_ do produto **Windows** e alguns produtos **Office**.*"

<img src="/img/tutorial/behind-a-proxy/image02.png">

一切正常。 ✔️

这是因为 FastAPI 在 OpenAPI 里使用 `root_path` 提供的 URL 创建默认 `server`。

## 附加的服务器

/// warning | 警告

此用例较难，可以跳过。

///

默认情况下，**FastAPI** 使用 `root_path` 的链接在 OpenAPI 概图中创建 `server`。

但也可以使用其它备选 `servers`，例如，需要同一个 API 文档与 staging 和生产环境交互。

Genau so, wie wir es wollten. ✔️

Dies liegt daran, dass FastAPI diesen `root_path` verwendet, um den Default-`server` in OpenAPI mit der von `root_path` bereitgestellten URL zu erstellen.

## Zusätzliche Server

/// warning | Achtung

Dies ist ein fortgeschrittener Anwendungsfall. Überspringen Sie das gerne.

///

Standardmäßig erstellt **FastAPI** einen `server` im OpenAPI-Schema mit der URL für den `root_path`.