## Créer une instance { #create-an-instance }

Nous pouvons créer une instance de cette classe avec :

{* ../../docs_src/dependencies/tutorial011_an_py310.py hl[18] *}

Et de cette façon, nous pouvons « paramétrer » notre dépendance, qui contient maintenant « bar », en tant qu’attribut `checker.fixed_content`.

## Utiliser l'instance comme dépendance { #use-the-instance-as-a-dependency }

      @ParametricNullness T instance) {
    return new SupplierOfInstance<>(instance);
  }

  private static final class SupplierOfInstance<T extends @Nullable Object>
      implements Supplier<T>, Serializable {
    @ParametricNullness final T instance;

    SupplierOfInstance(@ParametricNullness T instance) {
      this.instance = instance;
    }

    @Override
    @ParametricNullness
    public T get() {

      @ParametricNullness T instance) {
    return new SupplierOfInstance<>(instance);
  }

  private static final class SupplierOfInstance<T extends @Nullable Object>
      implements Supplier<T>, Serializable {
    @ParametricNullness final T instance;

    SupplierOfInstance(@ParametricNullness T instance) {
      this.instance = instance;
    }

    @Override
    @ParametricNullness
    public T get() {

                  Class<Unsafe> k = Unsafe.class;
                  for (Field f : k.getDeclaredFields()) {
                    f.setAccessible(true);
                    Object x = f.get(null);
                    if (k.isInstance(x)) {
                      return k.cast(x);
                    }
                  }
                  throw new NoSuchFieldError("the Unsafe");
                });
      } catch (PrivilegedActionException e) {

Il suffit de traiter la requête dans un bloc `try`/`except` :

{* ../../docs_src/custom_request_and_route/tutorial002_an_py310.py hl[14,16] *}

Si une exception se produit, l'instance de `Request` sera toujours dans la portée, ce qui nous permet de lire et d'utiliser le corps de la requête lors du traitement de l'erreur :

{* ../../docs_src/custom_request_and_route/tutorial002_an_py310.py hl[17:19] *}

            sqlalchemy_safe=sqlalchemy_safe,
        )
    if isinstance(obj, Enum):
        return obj.value
    if isinstance(obj, PurePath):
        return str(obj)
    if isinstance(obj, (str, int, float, type(None))):
        return obj
    if isinstance(obj, PydanticUndefinedType):
        return None
    if isinstance(obj, dict):
        encoded_dict = {}
        allowed_keys = set(obj.keys())

   *
   * <p><b>Discouraged:</b> Prefer using {@code clazz::isInstance} or {@code x -> x instanceof
   * Clazz}, but note that lambdas do not have human-readable {@link #toString()} representations
   * and are not serializable.
   */
  @GwtIncompatible // Class.isInstance
  public static <T extends @Nullable Object> Predicate<T> instanceOf(Class<?> clazz) {

   *
   * <p><b>Discouraged:</b> Prefer using {@code clazz::isInstance} or {@code x -> x instanceof
   * Clazz}, but note that lambdas do not have human-readable {@link #toString()} representations
   * and are not serializable.
   */
  @GwtIncompatible // Class.isInstance
  public static <T extends @Nullable Object> Predicate<T> instanceOf(Class<?> clazz) {

      this.wrapped = checkNotNull(wrapped);
    }

    @Override
    public boolean equals(@Nullable Object obj) {
      // In general getClass().isInstance() is bad for equals.
      // But here we fully control the subclasses to ensure symmetry.
      if (getClass().isInstance(obj)) {
        Wrapper that = (Wrapper) obj;
        return wrapped.equals(that.wrapped);
      }
      return false;
    }

    @Override

        and field_annotation_is_sequence(field.field_info.annotation)
        and isinstance(values, (ImmutableMultiDict, Headers))
    ):
        value = values.getlist(alias)
    else:
        value = values.get(alias, None)
    if (
        value is None
        or (
            isinstance(field.field_info, params.Form)
            and isinstance(value, str)  # For type checks
            and value == ""
        )