diff options
Diffstat (limited to 'Doc')
| -rw-r--r-- | Doc/library/stdtypes.rst | 13 | ||||
| -rw-r--r-- | Doc/reference/datamodel.rst | 6 |
2 files changed, 14 insertions, 5 deletions
diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst index 3f09b19..e076cbb 100644 --- a/Doc/library/stdtypes.rst +++ b/Doc/library/stdtypes.rst @@ -3761,11 +3761,13 @@ pairs within braces, for example: ``{'jack': 4098, 'sjoerd': 4127}`` or ``{4098: Return the item of *d* with key *key*. Raises a :exc:`KeyError` if *key* is not in the map. - If a subclass of dict defines a method :meth:`__missing__`, if the key *key* + .. index:: __missing__() + + If a subclass of dict defines a method :meth:`__missing__` and *key* is not present, the ``d[key]`` operation calls that method with the key *key* as argument. The ``d[key]`` operation then returns or raises whatever is - returned or raised by the ``__missing__(key)`` call if the key is not - present. No other operations or methods invoke :meth:`__missing__`. If + returned or raised by the ``__missing__(key)`` call. + No other operations or methods invoke :meth:`__missing__`. If :meth:`__missing__` is not defined, :exc:`KeyError` is raised. :meth:`__missing__` must be a method; it cannot be an instance variable:: @@ -3779,8 +3781,9 @@ pairs within braces, for example: ``{'jack': 4098, 'sjoerd': 4127}`` or ``{4098: >>> c['red'] 1 - See :class:`collections.Counter` for a complete implementation including - other methods helpful for accumulating and managing tallies. + The example above shows part of the implementation of + :class:`collections.Counter`. A different ``__missing__`` method is used + by :class:`collections.defaultdict`. .. describe:: d[key] = value diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst index 618c257..d0eede7 100644 --- a/Doc/reference/datamodel.rst +++ b/Doc/reference/datamodel.rst @@ -1904,6 +1904,12 @@ through the container; for mappings, :meth:`__iter__` should be the same as indexes to allow proper detection of the end of the sequence. +.. method:: object.__missing__(self, key) + + Called by :class:`dict`\ .\ :meth:`__getitem__` to implement ``self[key]`` for dict subclasses + when key is not in the dictionary. + + .. method:: object.__setitem__(self, key, value) Called to implement assignment to ``self[key]``. Same note as for |