from typing import Annotated, Any, Callable

from annotated_doc import Doc
from starlette.background import BackgroundTasks as StarletteBackgroundTasks
from typing_extensions import ParamSpec

P = ParamSpec("P")


class BackgroundTasks(StarletteBackgroundTasks):
    """
    A collection of background tasks that will be called after a response has been
    sent to the client.

    Read more about it in the

  }

  @Override
  public <T extends @Nullable Object> List<Future<T>> invokeAll(
      Collection<? extends Callable<T>> tasks) throws InterruptedException {
    return delegate().invokeAll(tasks);
  }

  @Override
  public <T extends @Nullable Object> List<Future<T>> invokeAll(
      Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
      throws InterruptedException {

    CountDownLatch enterLatch = new CountDownLatch(1);
    CountDownLatch exitLatch = new CountDownLatch(1);
    TrustedListenableFutureTask<@Nullable Void> task =
        TrustedListenableFutureTask.create(
            new Callable<@Nullable Void>() {
              @Override
              public @Nullable Void call() throws Exception {
                enterLatch.countDown();
                new CountDownLatch(1).await(); // wait forever

    }
  }

  private static List<Callable<String>> createTasks(int n) {
    List<Callable<String>> callables = new ArrayList<>();
    for (int i = 0; i < n; i++) {
      callables.add(Callables.returning(RESULT_VALUE + i));
    }
    return callables;
  }

  private static final class WrappedCallable<T> implements Callable<T> {
    private final Callable<T> delegate;

  /**
   * Creates a {@code ListenableFutureTask} that will upon running, execute the given {@code
   * Callable}.
   *
   * @param callable the callable task
   * @since 10.0
   */
  public static <V extends @Nullable Object> ListenableFutureTask<V> create(Callable<V> callable) {
    return new ListenableFutureTask<>(callable);
  }

  /**
   * Creates a {@code ListenableFutureTask} that will upon running, execute the given {@code

  /**
   * Creates a {@code ListenableFutureTask} that will upon running, execute the given {@code
   * Callable}.
   *
   * @param callable the callable task
   * @since 10.0
   */
  public static <V extends @Nullable Object> ListenableFutureTask<V> create(Callable<V> callable) {
    return new ListenableFutureTask<>(callable);
  }

  /**
   * Creates a {@code ListenableFutureTask} that will upon running, execute the given {@code

client = TestClient(app)


@pytest.mark.parametrize(
    "route,value",
    [
        ("/callable-dependency", "callable-dependency"),
        ("/callable-gen-dependency", "callable-gen-dependency"),
        ("/async-callable-dependency", "async-callable-dependency"),
        ("/async-callable-gen-dependency", "async-callable-gen-dependency"),
        ("/synchronous-method-dependency", "synchronous-method-dependency"),

Eine Python-Klasse ist also auch ein **Callable**.

Darum können Sie in **FastAPI** auch eine Python-Klasse als Abhängigkeit verwenden.

Was FastAPI tatsächlich prüft, ist, ob es sich um ein „Callable“ (Funktion, Klasse oder irgendetwas anderes) handelt und ob die Parameter definiert sind.

        ("/partial-callable-dependency", "partial-callable-dependency"),
        ("/partial-callable-gen-dependency", "partial-callable-gen-dependency"),
        ("/partial-async-callable-dependency", "partial-async-callable-dependency"),
        (
            "/partial-async-callable-gen-dependency",
            "partial-async-callable-gen-dependency",
        ),
        (

  @Override
  @ParametricNullness
  public <T extends @Nullable Object> T callWithTimeout(
      Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit) throws ExecutionException {
    checkNotNull(callable);
    checkNotNull(timeoutUnit);
    try {
      return callable.call();
    } catch (RuntimeException e) {
      throw new UncheckedExecutionException(e);