如果你在带有 `yield` 的依赖中使用了 `try` 代码块，那么当使用该依赖时抛出的任何异常你都会收到。

例如，如果在中间的某处代码中（在另一个依赖或在某个 *路径操作* 中）发生了数据库事务“回滚”或产生了其他异常，你会在你的依赖中收到这个异常。

因此，你可以在该依赖中用 `except SomeException` 来捕获这个特定异常。

同样地，你可以使用 `finally` 来确保退出步骤一定会被执行，无论是否发生异常。

{* ../../docs_src/dependencies/tutorial007_py310.py hl[3,5] *}

## 使用 `yield` 的子依赖项 { #sub-dependencies-with-yield }

你可以声明任意大小和形状的子依赖及其“树”，其中任意一个或全部都可以使用 `yield`。

    }

    @Override
    protected int delegateUpdate(final Entity entity, final UpdateOption<? extends ConditionBean> option) {
        final EsAbstractEntity esEntity = (EsAbstractEntity) entity;
        final IndexRequestBuilder builder = createUpdateRequest(esEntity);

        final IndexResponse response = builder.execute().actionGet(indexTimeout);
        final long seqNo = response.getSeqNo();

 */
public class SecureKeyManager implements AutoCloseable {

    private static final Logger log = LoggerFactory.getLogger(SecureKeyManager.class);

    private final Map<String, SecretKey> sessionKeys = new ConcurrentHashMap<>();
    private final Map<String, byte[]> rawKeys = new ConcurrentHashMap<>();
    private final SecureRandom secureRandom = new SecureRandom();
    private KeyStore keyStore;

import jcifs.util.Hexdump;

/**
 *
 */
final class SmbSessionImpl implements SmbSessionInternal {

    private static final Logger log = LoggerFactory.getLogger(SmbSessionImpl.class);

    /*
     * 0 - not connected
     * 1 - connecting
     * 2 - connected
     * 3 - disconnecting
     */
    private final AtomicInteger connectionState = new AtomicInteger();
    private int uid;

            assertNotNull(providedTimeZone);
            // The provider uses the static centralTimeZone which captures the original default
            assertEquals(originalDefault, providedTimeZone);
        } finally {
            // Restore original timezone
            TimeZone.setDefault(originalDefault);
        }
    }

    @Test
    public void test_processDBFluteSystem_unlocksAndLocks() {

    public void close() throws IOException {
        state = RdmaConnectionState.CLOSING;

        try {
            if (socketChannel != null) {
                socketChannel.close();
            }
        } finally {
            state = RdmaConnectionState.CLOSED;
        }

        log.debug("TCP RDMA connection closed");
    }

                        if (allNonces.putIfAbsent(nonceStr, true) != null) {
                            collisions.incrementAndGet();
                        }
                    }
                } finally {
                    latch.countDown();
                }
            });
        }

        // Then
        assertTrue(latch.await(10, TimeUnit.SECONDS), "All threads should complete");

    protected Hc4Authentication[] convertFromConfig(final WebAuthenticationConfig[] configs) {
        final List<Hc4Authentication> result = new ArrayList<>();
        for (final WebAuthenticationConfig config : configs) {
            try {
                final AuthScope authScope = new AuthScope(config.getHost(), config.getPort(), config.getRealm(), config.getScheme());

    }

    @Override
    protected int delegateUpdate(final Entity entity, final UpdateOption<? extends ConditionBean> option) {
        final EsAbstractEntity esEntity = (EsAbstractEntity) entity;
        final IndexRequestBuilder builder = createUpdateRequest(esEntity);

        final IndexResponse response = builder.execute().actionGet(indexTimeout);
        final long seqNo = response.getSeqNo();

So, you can look for that specific exception inside the dependency with `except SomeException`.

In the same way, you can use `finally` to make sure the exit steps are executed, no matter if there was an exception or not.

{* ../../docs_src/dependencies/tutorial007_py310.py hl[3,5] *}

## Sub-dependencies with `yield` { #sub-dependencies-with-yield }