# 使用yield的依赖项

FastAPI支持在完成后执行一些<abbr title='有时也被称为"退出"("exit")，"清理"("cleanup")，"拆卸"("teardown")，"关闭"("close")，"上下文管理器"("context managers")。 ...'>额外步骤</abbr>的依赖项.

为此，你需要使用 `yield` 而不是 `return`，然后再编写这些额外的步骤（代码）。

/// tip | 提示

确保在每个依赖中只使用一次 `yield`。

///

/// note | "技术细节"

任何一个可以与以下内容一起使用的函数：

TF_CAPI_EXPORT extern void TFE_ExecutorWaitForAllPendingNodes(
    TFE_Executor*, TF_Status* status);

// When an error happens, any pending operations are discarded, and newly issued
// ops return an error. This call clears the error state and re-enables
// execution of newly issued ops.
//
// Note that outputs of discarded ops remain in a corrupt state and should not
// be used for future calls.

			for attempts <= 3 {
				aerr := api.AbortMultipartUpload(ctx, tgtBucket, tgtObject, res.UploadID, ObjectOptions{})
				if aerr == nil {
					return
				}
				batchLogIf(ctx,
					fmt.Errorf("trying %s: Unable to cleanup failed multipart replication %s on remote %s/%s: %w - this may consume space on remote cluster",
						humanize.Ordinal(attempts), res.UploadID, tgtBucket, tgtObject, aerr))
				attempts++
				time.Sleep(time.Second)
			}

       "  Write-Error 'Error: Failed to validate Maven wrapper SHA-256, your Maven wrapper might be compromised.';"^
       "  Write-Error 'Investigate or delete %WRAPPER_JAR% to attempt a clean download.';"^
       "  Write-Error 'If you updated your Maven version, you need to update the specified wrapperSha256Sum property.';"^
       "  exit 1;"^
       "}"^
       "}"
    if ERRORLEVEL 1 goto error
)

  - [Changelog since v1.25.14](#changelog-since-v12514)
  - [Changes by Kind](#changes-by-kind)
    - [Feature](#feature)
    - [Bug or Regression](#bug-or-regression)
    - [Other (Cleanup or Flake)](#other-cleanup-or-flake)
  - [Dependencies](#dependencies-1)
    - [Added](#added-1)
    - [Changed](#changed-1)
    - [Removed](#removed-1)
- [v1.25.14](#v12514)
  - [Downloads for v1.25.14](#downloads-for-v12514)

    println("\n\nRequest to ${server2.inetSocketAddress}")
    executeSynchronously(request)
      .apply {
        // We may have a single failed request if not clean shutdown
        if (cleanShutdown) {
          assertSuccessful()
          assertCode(200)

          assertThat(server2.requestCount).isEqualTo(1)
        } else {

    assertEquals(liveCount, countLiveEntries(map));
    ImmutableMap<Object, Object> originalMap = ImmutableMap.copyOf(map);
    assertEquals(liveCount, originalMap.size());
    // can't compare map contents until cleanup occurs

    for (int i = 1; i <= originalCount * 2; i *= 2) {
      if (i > 1) {
        // TODO(b/145386688): This access should be guarded by 'segment', which is not currently
        // held

    assertEquals(liveCount, countLiveEntries(map));
    ImmutableMap<Object, Object> originalMap = ImmutableMap.copyOf(map);
    assertEquals(liveCount, originalMap.size());
    // can't compare map contents until cleanup occurs

    for (int i = 1; i <= originalCount * 2; i *= 2) {
      if (i > 1) {
        // TODO(b/145386688): This access should be guarded by 'segment', which is not currently
        // held

			}
			diskHealthCheckOK(ctx, err)
			return err
		}
		diskHealthCheckOK(ctx, err)
		if len(entries) == 0 {
			return nil
		}
		dirObjects := make(map[string]struct{})

		// Avoid a bunch of cleanup when joining.
		current = strings.Trim(current, SlashSeparator)
		for i, entry := range entries {
			if opts.Limit > 0 && objsReturned >= opts.Limit {
				return nil
			}

# yieldを持つ依存関係

FastAPIは、いくつかの<abbr title='時々"exit"、"cleanup"、"teardown"、"close"、"context managers"、 ...のように呼ばれる'>終了後の追加のステップ</abbr>を行う依存関係をサポートしています。

これを行うには、`return`の代わりに`yield`を使い、その後に追加のステップを書きます。

/// tip | "豆知識"

`yield`は必ず一度だけ使用するようにしてください。

///

/// info | "情報"

これを動作させるには、**Python 3.7** 以上を使用するか、**Python 3.6** では"backports"をインストールする必要があります:

```
pip install async-exit-stack async-generator
```