* Tener lógica compartida (la misma lógica de código una y otra vez).
* Compartir conexiones a bases de datos.
* Imponer seguridad, autenticación, requisitos de roles, etc.
* Y muchas otras cosas...

Todo esto, mientras minimizas la repetición de código.

## Primeros Pasos

Veamos un ejemplo muy simple. Será tan simple que no es muy útil, por ahora.

  // TODO(b/192446998): Remove this override after tools understand nullness better.
  public @Nullable V put(K key, @ParametricNullness V value) {
    return super.put(key, value);
  }

  @CanIgnoreReturnValue
  @Override
  @SuppressWarnings("RedundantOverride") // b/192446478: RedundantOverride ignores some annotations.

    protected void setupListCondition(final BadWordCB cb, final BadWordPager badWordPager) {
        if (badWordPager.id != null) {
            cb.query().docMeta().setId_Equal(badWordPager.id);
        }
        // TODO Long, Integer, String supported only.

        // setup condition
        cb.query().addOrderBy_SuggestWord_Asc();

        // search

    }

    /**
     * Imports bad words from a CSV file.

    } finally {
      notJar.delete();
    }
  }

  public void testGetClassPathEntry() throws MalformedURLException, URISyntaxException {
    if (isWindows()) {
      return; // TODO: b/136041958 - We need to account for drive letters in the path.
    }
    assertEquals(
        new File("/usr/test/dep.jar").toURI(),

    }
    return join(parts.iterator());
  }

  /*
   * TODO: b/381289911 - Make the Iterator overload use StringJoiner (including Android or not)—or
   * some other optimization, given that StringJoiner can over-allocate:
   * https://bugs.openjdk.org/browse/JDK-8305774
   */

  // TODO: b/381289911 - Optimize MapJoiner similarly to Joiner (including Android or not).

  /**

    protected void setupListCondition(final RoleTypeCB cb, final RoleTypePager roleTypePager) {
        if (roleTypePager.id != null) {
            cb.query().docMeta().setId_Equal(roleTypePager.id);
        }
        // TODO Long, Integer, String supported only.

        // setup condition
        cb.query().addOrderBy_SortOrder_Asc();
        cb.query().addOrderBy_Name_Asc();
        // search

    }

    /**

  private @Nullable Iterator<E> iterator;

  private MinimalIterable(Iterator<E> iterator) {
    this.iterator = iterator;
  }

  @Override
  public Iterator<E> iterator() {
    if (iterator == null) {
      // TODO: throw something else? Do we worry that people's code and tests
      // might be relying on this particular type of exception?
      throw new IllegalStateException();
    }
    try {
      return iterator;

import com.google.common.base.Supplier;
import com.google.errorprone.annotations.Immutable;

/**
 * Explicitly named subinterface of {@link Supplier} that can be marked {@literal @}{@link
 * Immutable}.
 */
// TODO(cpovirk): Should we just use ChecksumType directly instead of defining this type?
@Immutable

          // If the delegate is already done, run the execution list immediately on the current
          // thread.
          executionList.execute();
          return;
        }

        // TODO(lukes): handle RejectedExecutionException
        adapterExecutor.execute(
            () -> {
              try {
                /*
                 * Threads from our private pool are never interrupted. Threads from a

https://rightcode.co.jp/author/jun link: https://rightcode.co.jp/blog/information-technology/fastapi-tutorial-todo-apps-admin-page-improvement title: '【第4回】FastAPIチュートリアル: toDoアプリを作ってみよう【管理者ページ改良編】' - author: ライトコードメディア編集部 author_link: https://rightcode.co.jp/author/jun link: https://rightcode.co.jp/blog/information-technology/fastapi-tutorial-todo-apps-authentication-user-registration title: '【第3回】FastAPIチュートリアル: toDoアプリを作ってみよう【認証・ユーザ登録編】' - author: ライトコードメディア編集部 author_link: https://rightcode.co.jp/author/jun...