@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);

    List<Callable<T>> tasks = ImmutableList.of();
    List<? extends Future<?>> unused = executor.invokeAll(tasks);
  }

  public void testListeningDecorator() throws Exception {
    ListeningExecutorService service = listeningDecorator(newDirectExecutorService());
    assertSame(service, listeningDecorator(service));
    List<Callable<String>> callables = ImmutableList.of(Callables.returning("x"));

    runConcurrentTest(
        numberOfThreads,
        new Callable<@Nullable Void>() {
          @Override
          public @Nullable Void call() throws Exception {
            long unused = ticker.read();
            return null;
          }
        });

    assertEquals(incrementByNanos * numberOfThreads, ticker.read());
  }

  /** Runs {@code callable} concurrently {@code numberOfThreads} times. */

        ("/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",
        ),
        (

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.

  ListenableScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit);

  /**
   * @since 15.0 (previously returned ScheduledFuture)
   */
  @Override
  <V extends @Nullable Object> ListenableScheduledFuture<V> schedule(
      Callable<V> callable, long delay, TimeUnit unit);

  /**
   * @since 15.0 (previously returned ScheduledFuture)
   */
  @Override
  ListenableScheduledFuture<?> scheduleAtFixedRate(

    runConcurrentTest(
        numberOfThreads,
        new Callable<@Nullable Void>() {
          @Override
          public @Nullable Void call() throws Exception {
            long unused = ticker.read();
            return null;
          }
        });

    assertEquals(incrementByNanos * numberOfThreads, ticker.read());
  }

  /** Runs {@code callable} concurrently {@code numberOfThreads} times. */

    return schedule(callable(command), delay, unit);
  }

  @Override
  public <V> ListenableScheduledFuture<V> schedule(
      Callable<V> callable, long delay, TimeUnit unit) {
    Preconditions.checkNotNull(callable, "callable must not be null!");
    Preconditions.checkNotNull(unit, "unit must not be null!");
    ListenableFuture<V> delegateFuture = submit(callable);

    return schedule(callable(command), delay, unit);
  }

  @Override
  public <V> ListenableScheduledFuture<V> schedule(
      Callable<V> callable, long delay, TimeUnit unit) {
    Preconditions.checkNotNull(callable, "callable must not be null!");
    Preconditions.checkNotNull(unit, "unit must not be null!");
    ListenableFuture<V> delegateFuture = submit(callable);

import com.google.common.annotations.J2ktIncompatible;
import java.util.concurrent.Callable;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import org.jspecify.annotations.Nullable;

/**
 * An abstract {@code ScheduledExecutorService} that allows subclasses to {@linkplain
 * #wrapTask(Callable) wrap} tasks before they are submitted to the underlying executor.
 *