Entonces, una clase en Python también es un **callable**.

Entonces, en **FastAPI**, podrías usar una clase de Python como una dependencia.

Lo que **FastAPI** realmente comprueba es que sea un "callable" (función, clase o cualquier otra cosa) y los parámetros definidos.

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.
 *

import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutionException;
import org.jspecify.annotations.Nullable;

/**
 * A semi-persistent mapping from keys to values. Cache entries are manually added using {@link
 * #get(Object, Callable)} or {@link #put(Object, Object)}, and are stored in the cache until either

   * @throws RejectedExecutionException if the task cannot be scheduled for execution
   * @since 28.2
   */
  public static <O extends @Nullable Object> ListenableFuture<O> submit(
      Callable<O> callable, Executor executor) {
    TrustedListenableFutureTask<O> task = TrustedListenableFutureTask.create(callable);
    executor.execute(task);
    return task;
  }

  /**

    assertFile(Relay.PREFIX_CLEAN, 20L, metadata.size, "abcdefghijklmnopqrst", metadata)
  }

  /** Returns a callable that reads all of source, closes it, and returns the bytes.  */
  private fun sourceReader(source: Source?): Callable<ByteString> =
    Callable {
      val buffer = Buffer()
      while (source!!.read(buffer, 16384) != -1L) {
      }
      source.close()
      buffer.readByteString()

        assertDoesNotThrow(() -> {
            cache.getBuffer();
            cache.releaseBuffer(new byte[1024]);
        }, "All BufferCache interface methods should be callable");
    }

    @Test
    @DisplayName("getBuffer should return non-null byte array")
    void testGetBufferContract() {
        // Given
        byte[] expectedBuffer = new byte[1024];

      return true;
    }

    @Override
    public void execute(Runnable runnable) {}

    @Override
    public <V> ListenableScheduledFuture<V> schedule(
        Callable<V> callable, long delay, TimeUnit unit) {
      return NeverScheduledFuture.create();
    }

    @Override
    public ListenableScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) {

        assertEquals(3, result.size());
        verify(watchHandle, times(1)).call();
    }

    /**
     * Test call() method as Callable in executor service
     */
    @Test
    void testCallAsCallable() throws Exception {
        // Create a real implementation for testing Callable behavior
        SmbWatchHandle realHandle = new SmbWatchHandle() {
            private int callCount = 0;

            @Override

 */

package com.google.common.util.concurrent;

import static com.google.common.truth.Truth.assertThat;

import com.google.common.collect.ImmutableList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.TimeUnit;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/**
 * Tests for {@link AbstractListeningExecutorService}.
 *
 * @author Colin Decker
 */

 */

package com.google.common.util.concurrent;

import static com.google.common.truth.Truth.assertThat;

import com.google.common.collect.ImmutableList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.TimeUnit;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/**
 * Tests for {@link AbstractListeningExecutorService}.
 *
 * @author Colin Decker
 */