### Ask to close { #ask-to-close }

If they reply, there's a high chance you would have solved their problem, congrats, **you're a hero**! 🦸

* Now, if that solved their problem, you can ask them to:

    * In GitHub Discussions: mark the comment as the **answer**.
    * In GitHub Issues: **close** the issue.

## Watch the GitHub repository { #watch-the-github-repository }

# 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
```

 *
 * <p><b>Warning:</b> The methods of {@code ForwardingBlockingDeque} forward <b>indiscriminately</b>
 * to the methods of the delegate. For example, overriding {@link #add} alone <b>will not</b> change
 * the behaviour of {@link #offer} which can lead to unexpected behaviour. In this case, you should
 * override {@code offer} as well, either providing your own implementation, or delegating to the

    // Test that listeners added both before and after the value is available
    // get called correctly.
    for (int i = 0; i < 20; i++) {

      // Right in the middle start up a thread to close the latch.
      if (i == 10) {
        new Thread(() -> latch.countDown()).start();
      }

      future.addListener(listenerLatch::countDown, exec);
    }

    assertSame(Boolean.TRUE, future.get());

    assertThrows(IllegalArgumentException.class, () -> reader.mark(-1));
  }

  public void testMethodsThrowWhenClosed() throws IOException {
    CharSequenceReader reader = new CharSequenceReader("");
    reader.close();

    assertThrows(IOException.class, () -> reader.read());

    assertThrows(IOException.class, () -> reader.read(new char[10]));

    assertThrows(IOException.class, () -> reader.read(new char[10], 0, 10));

   * @param frqReference a phantom reference to the FinalizableReferenceQueue, which will be queued
   *     either when the FinalizableReferenceQueue is no longer referenced anywhere, or when its
   *     close() method is called.
   */
  public static void startFinalizer(
      Class<?> finalizableReferenceClass,
      ReferenceQueue<Object> queue,
      PhantomReference<Object> frqReference) {
    /*

    }
  }

  // Avoid infinite recursion if a closeable's close() method throws RejectedExecutionException and
  // is closed using the direct executor.
  public void testCloseThrowsRejectedExecutionException() throws Exception {
    doThrow(new RejectedExecutionException()).when(mockCloseable).close();
    ClosingFuture<Closeable> closingFuture =
        ClosingFuture.submit(

			xioutil.SafeClose(c.done)
			c.done = nil
		}
	}
	return n, err
}

func (c *closeNotifier) Close() error {
	if c.done != nil {
		xioutil.SafeClose(c.done)
		c.done = nil
	}
	return c.rc.Close()
}

// keepHTTPReqResponseAlive can be used to avoid timeouts with long storage
// operations, such as bitrot verification or data usage scanning.
// Every 10 seconds a space character is sent.

In fact, FastAPI uses those two decorators internally.

///

## A database dependency with `yield` { #a-database-dependency-with-yield }

For example, you could use this to create a database session and close it after finishing.

Only the code prior to and including the `yield` statement is executed before creating a response:

{* ../../docs_src/dependencies/tutorial007.py hl[2:4] *}

	if i := Index(s, sep); i >= 0 {
		return s[:i], s[i+len(sep):], true
	}
	return s, nil, false
}

// Clone returns a copy of b[:len(b)].
// The result may have additional unused capacity.
// Clone(nil) returns nil.
func Clone(b []byte) []byte {
	if b == nil {
		return nil
	}
	return append([]byte{}, b...)
}