"collections.abc" --- Abstract Base Classes for Containers
**********************************************************

Added in version 3.3: Anteriormente, este módulo formaba parte del
módulo "collections".

**Código fuente:** Lib/_collections_abc.py

======================================================================

This module provides *abstract base classes* that can be used to test
whether a class provides a particular interface; for example, whether
it is *hashable* or whether it is a *mapping*.

Una prueba "issubclass()" o "isinstance()" para una interfaz funciona
de tres formas.

1. A newly written class can inherit directly from one of the abstract
   base classes.  The class must supply the required abstract methods.
   The remaining mixin methods come from inheritance and can be
   overridden if desired.  Other methods may be added as needed:

      class C(Sequence):                      # Direct inheritance
          def __init__(self): ...             # Extra method not required by the ABC
          def __getitem__(self, index):  ...  # Required abstract method
          def __len__(self):  ...             # Required abstract method
          def count(self, value): ...         # Optionally override a mixin method

      >>> issubclass(C, Sequence)
      True
      >>> isinstance(C(), Sequence)
      True

2. Existing classes and built-in classes can be registered as "virtual
   subclasses" of the ABCs.  Those classes should define the full API
   including all of the abstract methods and all of the mixin methods.
   This lets users rely on "issubclass()" or "isinstance()" tests to
   determine whether the full interface is supported.  The exception
   to this rule is for methods that are automatically inferred from
   the rest of the API:

      class D:                                 # No inheritance
          def __init__(self): ...              # Extra method not required by the ABC
          def __getitem__(self, index):  ...   # Abstract method
          def __len__(self):  ...              # Abstract method
          def count(self, value): ...          # Mixin method
          def index(self, value): ...          # Mixin method

      Sequence.register(D)                     # Register instead of inherit

      >>> issubclass(D, Sequence)
      True
      >>> isinstance(D(), Sequence)
      True

   In this example, class "D" does not need to define "__contains__",
   "__iter__", and "__reversed__" because the in-operator, the
   *iteration* logic, and the "reversed()" function automatically fall
   back to using "__getitem__" and "__len__".

3. Some simple interfaces are directly recognizable by the presence of
   the required methods (unless those methods have been set to
   "None"):

      class E:
          def __iter__(self): ...
          def __next__(self): ...

      >>> issubclass(E, Iterable)
      True
      >>> isinstance(E(), Iterable)
      True

   Las interfaces complejas no admiten esta última técnica porque una
   interfaz es más que la simple presencia de nombres de métodos. Las
   interfaces especifican la semántica y las relaciones entre métodos
   que no se pueden inferir únicamente de la presencia de nombres de
   métodos específicos. Por ejemplo, saber que una clase proporciona
   "__getitem__", "__len__" y "__iter__" no es suficiente para
   distinguir un "Sequence" de un "Mapping".

Added in version 3.9: Estas clases abstractas ahora soportan "[]". Vea
Tipo Alias Genérico y **PEP 585**.


Colecciones clases base abstractas
==================================

El módulo de colecciones ofrece lo siguiente *ABCs*:

+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| ABC                            | Hereda de              | Métodos abstractos      | Métodos mixin                                        |
|================================|========================|=========================|======================================================|
| "Container" [1]                |                        | "__contains__"          |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "Hashable" [1]                 |                        | "__hash__"              |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "Iterable" [1] [2]             |                        | "__iter__"              |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "Iterator" [1]                 | "Iterable"             | "__next__"              | "__iter__"                                           |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "Reversible" [1]               | "Iterable"             | "__reversed__"          |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "Generator" [1]                | "Iterator"             | "send", "throw"         | "close", "__iter__", "__next__"                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "Sized" [1]                    |                        | "__len__"               |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "Callable" [1]                 |                        | "__call__"              |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "Collection" [1]               | "Sized", "Iterable",   | "__contains__",         |                                                      |
|                                | "Container"            | "__iter__", "__len__"   |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "Sequence"                     | "Reversible",          | "__getitem__",          | "__contains__", "__iter__", "__reversed__", "index", |
|                                | "Collection"           | "__len__"               | and "count"                                          |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "MutableSequence"              | "Sequence"             | "__getitem__",          | Inherited "Sequence" methods and "append", "clear",  |
|                                |                        | "__setitem__",          | "reverse", "extend", "pop", "remove", and "__iadd__" |
|                                |                        | "__delitem__",          |                                                      |
|                                |                        | "__len__", "insert"     |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "ByteString"                   | "Sequence"             | "__getitem__",          | Métodos heredados "Sequence"                         |
|                                |                        | "__len__"               |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "Set"                          | "Collection"           | "__contains__",         | "__le__", "__lt__", "__eq__", "__ne__", "__gt__",    |
|                                |                        | "__iter__", "__len__"   | "__ge__", "__and__", "__or__", "__sub__",            |
|                                |                        |                         | "__rsub__", "__xor__", "__rxor__" and "isdisjoint"   |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "MutableSet"                   | "Set"                  | "__contains__",         | Métodos heredados "Set" y "clear", "pop", "remove",  |
|                                |                        | "__iter__", "__len__",  | "__ior__", "__iand__", "__ixor__", and "__isub__"    |
|                                |                        | "add", "discard"        |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "Mapping"                      | "Collection"           | "__getitem__",          | "__contains__", "keys", "items", "values", "get",    |
|                                |                        | "__iter__", "__len__"   | "__eq__", and "__ne__"                               |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "MutableMapping"               | "Mapping"              | "__getitem__",          | Métodos heredados "Mapping" y "pop", "popitem",      |
|                                |                        | "__setitem__",          | "clear", "update", and "setdefault"                  |
|                                |                        | "__delitem__",          |                                                      |
|                                |                        | "__iter__", "__len__"   |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "MappingView"                  | "Sized"                |                         | "__init__", "__len__" and "__repr__"                 |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "ItemsView"                    | "MappingView", "Set"   |                         | "__contains__", "__iter__"                           |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "KeysView"                     | "MappingView", "Set"   |                         | "__contains__", "__iter__"                           |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "ValuesView"                   | "MappingView",         |                         | "__contains__", "__iter__"                           |
|                                | "Collection"           |                         |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "Awaitable" [1]                |                        | "__await__"             |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "Coroutine" [1]                | "Awaitable"            | "send", "throw"         | "close"                                              |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "AsyncIterable" [1]            |                        | "__aiter__"             |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "AsyncIterator" [1]            | "AsyncIterable"        | "__anext__"             | "__aiter__"                                          |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "AsyncGenerator" [1]           | "AsyncIterator"        | "asend", "athrow"       | "aclose", "__aiter__", "__anext__"                   |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+
| "Buffer" [1]                   |                        | "__buffer__"            |                                                      |
+--------------------------------+------------------------+-------------------------+------------------------------------------------------+

-[ Notas al pie ]-

[1] These ABCs override "__subclasshook__()" to support testing an
    interface by verifying the required methods are present and have
    not been set to "None".  This only works for simple interfaces.
    More complex interfaces require registration or direct
    subclassing.

[2] Checking "isinstance(obj, Iterable)" detects classes that are
    registered as "Iterable" or that have an "__iter__()" method, but
    it does not detect classes that iterate with the "__getitem__()"
    method.  The only reliable way to determine whether an object is
    *iterable* is to call "iter(obj)".


Colecciones Clases base abstractas - Descripciones detalladas
=============================================================

class collections.abc.Container

   ABC for classes that provide the "__contains__()" method.

class collections.abc.Hashable

   ABC for classes that provide the "__hash__()" method.

class collections.abc.Sized

   ABC for classes that provide the "__len__()" method.

class collections.abc.Callable

   ABC for classes that provide the "__call__()" method.

   See Anotaciones en objetos invocables for details on how to use
   "Callable" in type annotations.

class collections.abc.Iterable

   ABC for classes that provide the "__iter__()" method.

   Checking "isinstance(obj, Iterable)" detects classes that are
   registered as "Iterable" or that have an "__iter__()" method, but
   it does not detect classes that iterate with the "__getitem__()"
   method. The only reliable way to determine whether an object is
   *iterable* is to call "iter(obj)".

class collections.abc.Collection

   ABC para clases de contenedor iterables de tamaño.

   Added in version 3.6.

class collections.abc.Iterator

   ABC para clases que proporcionan el método "__iter__()" y
   "__next__()". Ver también la definición de *iterator*.

class collections.abc.Reversible

   ABC for iterable classes that also provide the "__reversed__()"
   method.

   Added in version 3.6.

class collections.abc.Generator

   ABC for *generator* classes that implement the protocol defined in
   **PEP 342** that extends *iterators* with the "send()", "throw()"
   and "close()" methods.

   See Annotating generators and coroutines for details on using
   "Generator" in type annotations.

   Added in version 3.5.

class collections.abc.Sequence
class collections.abc.MutableSequence
class collections.abc.ByteString

   ABC para solo lectura y mutable *secuencias*.

   Implementation note: Some of the mixin methods, such as
   "__iter__()", "__reversed__()" and "index()", make repeated calls
   to the underlying "__getitem__()" method. Consequently, if
   "__getitem__()" is implemented with constant access speed, the
   mixin methods will have linear performance; however, if the
   underlying method is linear (as it would be with a linked list),
   the mixins will have quadratic performance and will likely need to
   be overridden.

   Distinto en la versión 3.5: El método index() agregó soporte para
   los argumentos *stop* y *start*.

   Deprecated since version 3.12, will be removed in version 3.14: La
   ABC "ByteString" está obsoleta. Para usar con "type hints", mejor
   use una unión del tipo "bytes | bytearray", o
   "collections.abc.Buffer". Para usar como una ABC, mejor use
   "Sequence" o "collections.abc.Buffer".

class collections.abc.Set
class collections.abc.MutableSet

   ABCs for read-only and mutable sets.

class collections.abc.Mapping
class collections.abc.MutableMapping

   ABC para solo lectura y mutable *mapeos*.

class collections.abc.MappingView
class collections.abc.ItemsView
class collections.abc.KeysView
class collections.abc.ValuesView

   ABC para mapeo, elementos, claves y valores *vistas*.

class collections.abc.Awaitable

   ABC for *awaitable* objects, which can be used in "await"
   expressions.  Custom implementations must provide the "__await__()"
   method.

   *Coroutine* objetos e instancias de la clase "Coroutine" ABC son
   todas las instancias de este ABC.

   Nota:

     In CPython, generator-based coroutines (*generators* decorated
     with "@types.coroutine") are *awaitables*, even though they do
     not have an "__await__()" method. Using "isinstance(gencoro,
     Awaitable)" for them will return "False". Use
     "inspect.isawaitable()" to detect them.

   Added in version 3.5.

class collections.abc.Coroutine

   ABC for *coroutine* compatible classes.  These implement the
   following methods, defined in Objetos de corrutina: "send()",
   "throw()", and "close()".  Custom implementations must also
   implement "__await__()".  All "Coroutine" instances are also
   instances of "Awaitable".

   Nota:

     In CPython, generator-based coroutines (*generators* decorated
     with "@types.coroutine") are *awaitables*, even though they do
     not have an "__await__()" method. Using "isinstance(gencoro,
     Coroutine)" for them will return "False". Use
     "inspect.isawaitable()" to detect them.

   See Annotating generators and coroutines for details on using
   "Coroutine" in type annotations. The variance and order of type
   parameters correspond to those of "Generator".

   Added in version 3.5.

class collections.abc.AsyncIterable

   ABC for classes that provide an "__aiter__" method.  See also the
   definition of *asynchronous iterable*.

   Added in version 3.5.

class collections.abc.AsyncIterator

   ABC para clases que proveen métodos "__aiter__" and "__anext__".
   Ver también la definición de *asynchronous iterator*.

   Added in version 3.5.

class collections.abc.AsyncGenerator

   ABC for *asynchronous generator* classes that implement the
   protocol defined in **PEP 525** and **PEP 492**.

   See Annotating generators and coroutines for details on using
   "AsyncGenerator" in type annotations.

   Added in version 3.6.

class collections.abc.Buffer

   ABC para clases que proveen el método "__buffer__()", implementando
   el protocolo búfer. Ver **PEP 688**.

   Added in version 3.12.


Ejemplos y Recetas
==================

Los ABC nos permiten preguntar a las clases o instancias si brindan
una funcionalidad particular, por ejemplo:

   size = None
   if isinstance(myvar, collections.abc.Sized):
       size = len(myvar)

Several of the ABCs are also useful as mixins that make it easier to
develop classes supporting container APIs.  For example, to write a
class supporting the full "Set" API, it is only necessary to supply
the three underlying abstract methods: "__contains__()", "__iter__()",
and "__len__()". The ABC supplies the remaining methods such as
"__and__()" and "isdisjoint()":

   class ListBasedSet(collections.abc.Set):
       ''' Alternate set implementation favoring space over speed
           and not requiring the set elements to be hashable. '''
       def __init__(self, iterable):
           self.elements = lst = []
           for value in iterable:
               if value not in lst:
                   lst.append(value)

       def __iter__(self):
           return iter(self.elements)

       def __contains__(self, value):
           return value in self.elements

       def __len__(self):
           return len(self.elements)

   s1 = ListBasedSet('abcdef')
   s2 = ListBasedSet('defghi')
   overlap = s1 & s2            # The __and__() method is supported automatically

Notas sobre el uso de "Set" y "MutableSet" como un mixin:

1. Since some set operations create new sets, the default mixin
   methods need a way to create new instances from an *iterable*. The
   class constructor is assumed to have a signature in the form
   "ClassName(iterable)". That assumption is factored-out to an
   internal "classmethod" called "_from_iterable()" which calls
   "cls(iterable)" to produce a new set. If the "Set" mixin is being
   used in a class with a different constructor signature, you will
   need to override "_from_iterable()" with a classmethod or regular
   method that can construct new instances from an iterable argument.

2. To override the comparisons (presumably for speed, as the semantics
   are fixed), redefine "__le__()" and "__ge__()", then the other
   operations will automatically follow suit.

3. The "Set" mixin provides a "_hash()" method to compute a hash value
   for the set; however, "__hash__()" is not defined because not all
   sets are *hashable* or immutable.  To add set hashability using
   mixins, inherit from both "Set()" and "Hashable()", then define
   "__hash__ = Set._hash".

Ver también:

  * OrderedSet receta para un ejemplo basado en "MutableSet".

  * Para obtener más información sobre ABCs, ver el módulo "abc" y
    **PEP 3119**.
