diff options
| -rw-r--r-- | Doc/glossary.rst | 12 | ||||
| -rw-r--r-- | Doc/library/stdtypes.rst | 14 | ||||
| -rw-r--r-- | Doc/reference/expressions.rst | 4 | ||||
| -rw-r--r-- | Misc/ACKS | 1 |
4 files changed, 31 insertions, 0 deletions
diff --git a/Doc/glossary.rst b/Doc/glossary.rst index 9fdbdb1..4f0654b 100644 --- a/Doc/glossary.rst +++ b/Doc/glossary.rst @@ -308,6 +308,12 @@ Glossary keys can be any object with :meth:`__hash__` and :meth:`__eq__` methods. Called a hash in Perl. + dictionary comprehension + A compact way to process all or part of the elements in an iterable and + return a dictionary with the results. ``results = {n: n ** 2 for n in + range(10)}`` generates a dictionary containing key ``n`` mapped to + value ``n ** 2``. See :ref:`comprehensions`. + dictionary view The objects returned from :meth:`dict.keys`, :meth:`dict.values`, and :meth:`dict.items` are called dictionary views. They provide a dynamic @@ -1026,6 +1032,12 @@ Glossary interface can be registered explicitly using :func:`~abc.register`. + set comprehension + A compact way to process all or part of the elements in an iterable and + return a set with the results. ``results = {c for c in 'abracadabra' if + c not in 'abc'}`` generates the set of strings ``{'r', 'd'}``. See + :ref:`comprehensions`. + single dispatch A form of :term:`generic function` dispatch where the implementation is chosen based on the type of a single argument. diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst index 2fc7a61..c74d164 100644 --- a/Doc/library/stdtypes.rst +++ b/Doc/library/stdtypes.rst @@ -4140,6 +4140,12 @@ The constructors for both classes work the same: objects. If *iterable* is not specified, a new empty set is returned. + Sets can be created by several means: + + * Use a comma-separated list of elements within braces: ``{'jack', 'sjoerd'}`` + * Use a set comprehension: ``{c for c in 'abracadabra' if c not in 'abc'}`` + * Use the type constructor: ``set()``, ``set('foobar')``, ``set(['a', 'b', 'foo'])`` + Instances of :class:`set` and :class:`frozenset` provide the following operations: @@ -4332,6 +4338,14 @@ pairs within braces, for example: ``{'jack': 4098, 'sjoerd': 4127}`` or ``{4098: Return a new dictionary initialized from an optional positional argument and a possibly empty set of keyword arguments. + Dictionaries can be created by several means: + + * Use a comma-separated list of ``key: value`` pairs within braces: + ``{'jack': 4098, 'sjoerd': 4127}`` or ``{4098: 'jack', 4127: 'sjoerd'}`` + * Use a dict comprehension: ``{}``, ``{x: x ** 2 for x in range(10)}`` + * Use the type constructor: ``dict()``, + ``dict([('foo', 100), ('bar', 200)])``, ``dict(foo=100, bar=200)`` + If no positional argument is given, an empty dictionary is created. If a positional argument is given and it is a mapping object, a dictionary is created with the same key-value pairs as the mapping object. Otherwise, diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst index b68c298..81dd6fc 100644 --- a/Doc/reference/expressions.rst +++ b/Doc/reference/expressions.rst @@ -162,6 +162,8 @@ ambiguities and allow common typos to pass uncaught. Displays for lists, sets and dictionaries ----------------------------------------- +.. index:: single: comprehensions + For constructing a list, a set or a dictionary Python provides special syntax called "displays", each of them in two flavors: @@ -260,6 +262,7 @@ Set displays .. index:: pair: set; display + pair: set; comprehensions object: set single: {} (curly brackets); set expression single: , (comma); expression list @@ -287,6 +290,7 @@ Dictionary displays .. index:: pair: dictionary; display + pair: dictionary; comprehensions key, datum, key/datum pair object: dictionary single: {} (curly brackets); dictionary expression @@ -382,6 +382,7 @@ Brian Curtin Jason Curtis Hakan Celik Paul Dagnelie +Florian Dahlitz Lisandro Dalcin Darren Dale Andrew Dalke |