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author | Ezio Melotti <none@none> | 2011-10-02 09:47:10 (GMT) |
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committer | Ezio Melotti <none@none> | 2011-10-02 09:47:10 (GMT) |
commit | 6fe679f011094d2cfa455292331071e1d0e35289 (patch) | |
tree | fef985d6963b24578dd5f3d7f6a36fb0e51196d9 /Doc | |
parent | 267aa24365b9fe6b142be49a2db2219f14c456b7 (diff) | |
parent | 35ec7f771b752631f73cfe52749edfe381df4807 (diff) | |
download | cpython-6fe679f011094d2cfa455292331071e1d0e35289.zip cpython-6fe679f011094d2cfa455292331071e1d0e35289.tar.gz cpython-6fe679f011094d2cfa455292331071e1d0e35289.tar.bz2 |
#13076: merge with 3.2.
Diffstat (limited to 'Doc')
-rw-r--r-- | Doc/library/datetime.rst | 152 |
1 files changed, 76 insertions, 76 deletions
diff --git a/Doc/library/datetime.rst b/Doc/library/datetime.rst index 73b3901..de034ff 100644 --- a/Doc/library/datetime.rst +++ b/Doc/library/datetime.rst @@ -18,13 +18,13 @@ functionality, see also the :mod:`time` and :mod:`calendar` modules. There are two kinds of date and time objects: "naive" and "aware". This distinction refers to whether the object has any notion of time zone, daylight saving time, or other kind of algorithmic or political time adjustment. Whether -a naive :class:`datetime` object represents Coordinated Universal Time (UTC), +a naive :class:`.datetime` object represents Coordinated Universal Time (UTC), local time, or time in some other timezone is purely up to the program, just like it's up to the program whether a particular number represents metres, -miles, or mass. Naive :class:`datetime` objects are easy to understand and to +miles, or mass. Naive :class:`.datetime` objects are easy to understand and to work with, at the cost of ignoring some aspects of reality. -For applications requiring more, :class:`datetime` and :class:`time` objects +For applications requiring more, :class:`.datetime` and :class:`.time` objects have an optional time zone information attribute, :attr:`tzinfo`, that can be set to an instance of a subclass of the abstract :class:`tzinfo` class. These :class:`tzinfo` objects capture information about the offset from UTC time, the @@ -41,13 +41,13 @@ The :mod:`datetime` module exports the following constants: .. data:: MINYEAR - The smallest year number allowed in a :class:`date` or :class:`datetime` object. + The smallest year number allowed in a :class:`date` or :class:`.datetime` object. :const:`MINYEAR` is ``1``. .. data:: MAXYEAR - The largest year number allowed in a :class:`date` or :class:`datetime` object. + The largest year number allowed in a :class:`date` or :class:`.datetime` object. :const:`MAXYEAR` is ``9999``. @@ -91,14 +91,14 @@ Available Types .. class:: timedelta :noindex: - A duration expressing the difference between two :class:`date`, :class:`time`, - or :class:`datetime` instances to microsecond resolution. + A duration expressing the difference between two :class:`date`, :class:`.time`, + or :class:`.datetime` instances to microsecond resolution. .. class:: tzinfo An abstract base class for time zone information objects. These are used by the - :class:`datetime` and :class:`time` classes to provide a customizable notion of + :class:`.datetime` and :class:`.time` classes to provide a customizable notion of time adjustment (for example, to account for time zone and/or daylight saving time). @@ -114,7 +114,7 @@ Objects of these types are immutable. Objects of the :class:`date` type are always naive. -An object *d* of type :class:`time` or :class:`datetime` may be naive or aware. +An object *d* of type :class:`.time` or :class:`.datetime` may be naive or aware. *d* is aware if ``d.tzinfo`` is not ``None`` and ``d.tzinfo.utcoffset(d)`` does not return ``None``. If ``d.tzinfo`` is ``None``, or if ``d.tzinfo`` is not ``None`` but ``d.tzinfo.utcoffset(d)`` returns ``None``, *d* is naive. @@ -299,7 +299,7 @@ Notes: -1 day, 19:00:00 In addition to the operations listed above :class:`timedelta` objects support -certain additions and subtractions with :class:`date` and :class:`datetime` +certain additions and subtractions with :class:`date` and :class:`.datetime` objects (see below). .. versionchanged:: 3.2 @@ -638,10 +638,10 @@ Example of working with :class:`date`: :class:`datetime` Objects ------------------------- -A :class:`datetime` object is a single object containing all the information -from a :class:`date` object and a :class:`time` object. Like a :class:`date` -object, :class:`datetime` assumes the current Gregorian calendar extended in -both directions; like a time object, :class:`datetime` assumes there are exactly +A :class:`.datetime` object is a single object containing all the information +from a :class:`date` object and a :class:`.time` object. Like a :class:`date` +object, :class:`.datetime` assumes the current Gregorian calendar extended in +both directions; like a time object, :class:`.datetime` assumes there are exactly 3600\*24 seconds in every day. Constructor: @@ -689,7 +689,7 @@ Other constructors, all class methods: Return the current UTC date and time, with :attr:`tzinfo` ``None``. This is like :meth:`now`, but returns the current UTC date and time, as a naive - :class:`datetime` object. An aware current UTC datetime can be obtained by + :class:`.datetime` object. An aware current UTC datetime can be obtained by calling ``datetime.now(timezone.utc)``. See also :meth:`now`. .. classmethod:: datetime.fromtimestamp(timestamp, tz=None) @@ -697,7 +697,7 @@ Other constructors, all class methods: Return the local date and time corresponding to the POSIX timestamp, such as is returned by :func:`time.time`. If optional argument *tz* is ``None`` or not specified, the timestamp is converted to the platform's local date and time, and - the returned :class:`datetime` object is naive. + the returned :class:`.datetime` object is naive. Else *tz* must be an instance of a class :class:`tzinfo` subclass, and the timestamp is converted to *tz*'s time zone. In this case the result is @@ -710,12 +710,12 @@ Other constructors, all class methods: 1970 through 2038. Note that on non-POSIX systems that include leap seconds in their notion of a timestamp, leap seconds are ignored by :meth:`fromtimestamp`, and then it's possible to have two timestamps differing by a second that yield - identical :class:`datetime` objects. See also :meth:`utcfromtimestamp`. + identical :class:`.datetime` objects. See also :meth:`utcfromtimestamp`. .. classmethod:: datetime.utcfromtimestamp(timestamp) - Return the UTC :class:`datetime` corresponding to the POSIX timestamp, with + Return the UTC :class:`.datetime` corresponding to the POSIX timestamp, with :attr:`tzinfo` ``None``. This may raise :exc:`ValueError`, if the timestamp is out of the range of values supported by the platform C :c:func:`gmtime` function. It's common for this to be restricted to years in 1970 through 2038. See also @@ -740,7 +740,7 @@ Other constructors, all class methods: .. classmethod:: datetime.fromordinal(ordinal) - Return the :class:`datetime` corresponding to the proleptic Gregorian ordinal, + Return the :class:`.datetime` corresponding to the proleptic Gregorian ordinal, where January 1 of year 1 has ordinal 1. :exc:`ValueError` is raised unless ``1 <= ordinal <= datetime.max.toordinal()``. The hour, minute, second and microsecond of the result are all 0, and :attr:`tzinfo` is ``None``. @@ -748,18 +748,18 @@ Other constructors, all class methods: .. classmethod:: datetime.combine(date, time) - Return a new :class:`datetime` object whose date components are equal to the + Return a new :class:`.datetime` object whose date components are equal to the given :class:`date` object's, and whose time components and :attr:`tzinfo` - attributes are equal to the given :class:`time` object's. For any - :class:`datetime` object *d*, + attributes are equal to the given :class:`.time` object's. For any + :class:`.datetime` object *d*, ``d == datetime.combine(d.date(), d.timetz())``. If date is a - :class:`datetime` object, its time components and :attr:`tzinfo` attributes + :class:`.datetime` object, its time components and :attr:`tzinfo` attributes are ignored. .. classmethod:: datetime.strptime(date_string, format) - Return a :class:`datetime` corresponding to *date_string*, parsed according to + Return a :class:`.datetime` corresponding to *date_string*, parsed according to *format*. This is equivalent to ``datetime(*(time.strptime(date_string, format)[0:6]))``. :exc:`ValueError` is raised if the date_string and format can't be parsed by :func:`time.strptime` or if it returns a value which isn't a @@ -771,19 +771,19 @@ Class attributes: .. attribute:: datetime.min - The earliest representable :class:`datetime`, ``datetime(MINYEAR, 1, 1, + The earliest representable :class:`.datetime`, ``datetime(MINYEAR, 1, 1, tzinfo=None)``. .. attribute:: datetime.max - The latest representable :class:`datetime`, ``datetime(MAXYEAR, 12, 31, 23, 59, + The latest representable :class:`.datetime`, ``datetime(MAXYEAR, 12, 31, 23, 59, 59, 999999, tzinfo=None)``. .. attribute:: datetime.resolution - The smallest possible difference between non-equal :class:`datetime` objects, + The smallest possible difference between non-equal :class:`.datetime` objects, ``timedelta(microseconds=1)``. @@ -826,24 +826,24 @@ Instance attributes (read-only): .. attribute:: datetime.tzinfo - The object passed as the *tzinfo* argument to the :class:`datetime` constructor, + The object passed as the *tzinfo* argument to the :class:`.datetime` constructor, or ``None`` if none was passed. Supported operations: -+---------------------------------------+-------------------------------+ -| Operation | Result | -+=======================================+===============================+ -| ``datetime2 = datetime1 + timedelta`` | \(1) | -+---------------------------------------+-------------------------------+ -| ``datetime2 = datetime1 - timedelta`` | \(2) | -+---------------------------------------+-------------------------------+ -| ``timedelta = datetime1 - datetime2`` | \(3) | -+---------------------------------------+-------------------------------+ -| ``datetime1 < datetime2`` | Compares :class:`datetime` to | -| | :class:`datetime`. (4) | -+---------------------------------------+-------------------------------+ ++---------------------------------------+--------------------------------+ +| Operation | Result | ++=======================================+================================+ +| ``datetime2 = datetime1 + timedelta`` | \(1) | ++---------------------------------------+--------------------------------+ +| ``datetime2 = datetime1 - timedelta`` | \(2) | ++---------------------------------------+--------------------------------+ +| ``timedelta = datetime1 - datetime2`` | \(3) | ++---------------------------------------+--------------------------------+ +| ``datetime1 < datetime2`` | Compares :class:`.datetime` to | +| | :class:`.datetime`. (4) | ++---------------------------------------+--------------------------------+ (1) datetime2 is a duration of timedelta removed from datetime1, moving forward in @@ -862,7 +862,7 @@ Supported operations: in isolation can overflow in cases where datetime1 - timedelta does not. (3) - Subtraction of a :class:`datetime` from a :class:`datetime` is defined only if + Subtraction of a :class:`.datetime` from a :class:`.datetime` is defined only if both operands are naive, or if both are aware. If one is aware and the other is naive, :exc:`TypeError` is raised. @@ -891,16 +891,16 @@ Supported operations: In order to stop comparison from falling back to the default scheme of comparing object addresses, datetime comparison normally raises :exc:`TypeError` if the - other comparand isn't also a :class:`datetime` object. However, + other comparand isn't also a :class:`.datetime` object. However, ``NotImplemented`` is returned instead if the other comparand has a :meth:`timetuple` attribute. This hook gives other kinds of date objects a - chance at implementing mixed-type comparison. If not, when a :class:`datetime` + chance at implementing mixed-type comparison. If not, when a :class:`.datetime` object is compared to an object of a different type, :exc:`TypeError` is raised unless the comparison is ``==`` or ``!=``. The latter cases return :const:`False` or :const:`True`, respectively. -:class:`datetime` objects can be used as dictionary keys. In Boolean contexts, -all :class:`datetime` objects are considered to be true. +:class:`.datetime` objects can be used as dictionary keys. In Boolean contexts, +all :class:`.datetime` objects are considered to be true. Instance methods: @@ -911,13 +911,13 @@ Instance methods: .. method:: datetime.time() - Return :class:`time` object with same hour, minute, second and microsecond. + Return :class:`.time` object with same hour, minute, second and microsecond. :attr:`tzinfo` is ``None``. See also method :meth:`timetz`. .. method:: datetime.timetz() - Return :class:`time` object with same hour, minute, second, microsecond, and + Return :class:`.time` object with same hour, minute, second, microsecond, and tzinfo attributes. See also method :meth:`time`. @@ -931,7 +931,7 @@ Instance methods: .. method:: datetime.astimezone(tz) - Return a :class:`datetime` object with new :attr:`tzinfo` attribute *tz*, + Return a :class:`.datetime` object with new :attr:`tzinfo` attribute *tz*, adjusting the date and time data so the result is the same UTC time as *self*, but in *tz*'s local time. @@ -1005,7 +1005,7 @@ Instance methods: .. method:: datetime.utctimetuple() - If :class:`datetime` instance *d* is naive, this is the same as + If :class:`.datetime` instance *d* is naive, this is the same as ``d.timetuple()`` except that :attr:`tm_isdst` is forced to 0 regardless of what ``d.dst()`` returns. DST is never in effect for a UTC time. @@ -1066,7 +1066,7 @@ Instance methods: .. method:: datetime.__str__() - For a :class:`datetime` instance *d*, ``str(d)`` is equivalent to + For a :class:`.datetime` instance *d*, ``str(d)`` is equivalent to ``d.isoformat(' ')``. @@ -1215,19 +1215,19 @@ Class attributes: .. attribute:: time.min - The earliest representable :class:`time`, ``time(0, 0, 0, 0)``. + The earliest representable :class:`.time`, ``time(0, 0, 0, 0)``. .. attribute:: time.max - The latest representable :class:`time`, ``time(23, 59, 59, 999999)``. + The latest representable :class:`.time`, ``time(23, 59, 59, 999999)``. .. attribute:: time.resolution - The smallest possible difference between non-equal :class:`time` objects, - ``timedelta(microseconds=1)``, although note that arithmetic on :class:`time` - objects is not supported. + The smallest possible difference between non-equal :class:`.time` objects, + ``timedelta(microseconds=1)``, although note that arithmetic on + :class:`.time` objects is not supported. Instance attributes (read-only): @@ -1254,13 +1254,13 @@ Instance attributes (read-only): .. attribute:: time.tzinfo - The object passed as the tzinfo argument to the :class:`time` constructor, or + The object passed as the tzinfo argument to the :class:`.time` constructor, or ``None`` if none was passed. Supported operations: -* comparison of :class:`time` to :class:`time`, where *a* is considered less +* comparison of :class:`.time` to :class:`.time`, where *a* is considered less than *b* when *a* precedes *b* in time. If one comparand is naive and the other is aware, :exc:`TypeError` is raised. If both comparands are aware, and have the same :attr:`tzinfo` attribute, the common :attr:`tzinfo` attribute is @@ -1268,7 +1268,7 @@ Supported operations: have different :attr:`tzinfo` attributes, the comparands are first adjusted by subtracting their UTC offsets (obtained from ``self.utcoffset()``). In order to stop mixed-type comparisons from falling back to the default comparison by - object address, when a :class:`time` object is compared to an object of a + object address, when a :class:`.time` object is compared to an object of a different type, :exc:`TypeError` is raised unless the comparison is ``==`` or ``!=``. The latter cases return :const:`False` or :const:`True`, respectively. @@ -1276,7 +1276,7 @@ Supported operations: * efficient pickling -* in Boolean contexts, a :class:`time` object is considered to be true if and +* in Boolean contexts, a :class:`.time` object is considered to be true if and only if, after converting it to minutes and subtracting :meth:`utcoffset` (or ``0`` if that's ``None``), the result is non-zero. @@ -1285,10 +1285,10 @@ Instance methods: .. method:: time.replace([hour[, minute[, second[, microsecond[, tzinfo]]]]]) - Return a :class:`time` with the same value, except for those attributes given + Return a :class:`.time` with the same value, except for those attributes given new values by whichever keyword arguments are specified. Note that - ``tzinfo=None`` can be specified to create a naive :class:`time` from an - aware :class:`time`, without conversion of the time data. + ``tzinfo=None`` can be specified to create a naive :class:`.time` from an + aware :class:`.time`, without conversion of the time data. .. method:: time.isoformat() @@ -1366,13 +1366,13 @@ Example: :class:`tzinfo` is an abstract base class, meaning that this class should not be instantiated directly. You need to derive a concrete subclass, and (at least) supply implementations of the standard :class:`tzinfo` methods needed by the -:class:`datetime` methods you use. The :mod:`datetime` module supplies +:class:`.datetime` methods you use. The :mod:`datetime` module supplies a simple concrete subclass of :class:`tzinfo` :class:`timezone` which can reprsent timezones with fixed offset from UTC such as UTC itself or North American EST and EDT. An instance of (a concrete subclass of) :class:`tzinfo` can be passed to the -constructors for :class:`datetime` and :class:`time` objects. The latter objects +constructors for :class:`.datetime` and :class:`.time` objects. The latter objects view their attributes as being in local time, and the :class:`tzinfo` object supports methods revealing offset of local time from UTC, the name of the time zone, and DST offset, all relative to a date or time object passed to them. @@ -1427,7 +1427,7 @@ methods. Exactly which methods are needed depends on the uses made of aware ``tz.utcoffset(dt) - tz.dst(dt)`` - must return the same result for every :class:`datetime` *dt* with ``dt.tzinfo == + must return the same result for every :class:`.datetime` *dt* with ``dt.tzinfo == tz`` For sane :class:`tzinfo` subclasses, this expression yields the time zone's "standard offset", which should not depend on the date or the time, but only on geographic location. The implementation of :meth:`datetime.astimezone` @@ -1459,7 +1459,7 @@ methods. Exactly which methods are needed depends on the uses made of aware .. method:: tzinfo.tzname(dt) - Return the time zone name corresponding to the :class:`datetime` object *dt*, as + Return the time zone name corresponding to the :class:`.datetime` object *dt*, as a string. Nothing about string names is defined by the :mod:`datetime` module, and there's no requirement that it mean anything in particular. For example, "GMT", "UTC", "-500", "-5:00", "EDT", "US/Eastern", "America/New York" are all @@ -1472,11 +1472,11 @@ methods. Exactly which methods are needed depends on the uses made of aware The default implementation of :meth:`tzname` raises :exc:`NotImplementedError`. -These methods are called by a :class:`datetime` or :class:`time` object, in -response to their methods of the same names. A :class:`datetime` object passes -itself as the argument, and a :class:`time` object passes ``None`` as the +These methods are called by a :class:`.datetime` or :class:`.time` object, in +response to their methods of the same names. A :class:`.datetime` object passes +itself as the argument, and a :class:`.time` object passes ``None`` as the argument. A :class:`tzinfo` subclass's methods should therefore be prepared to -accept a *dt* argument of ``None``, or of class :class:`datetime`. +accept a *dt* argument of ``None``, or of class :class:`.datetime`. When ``None`` is passed, it's up to the class designer to decide the best response. For example, returning ``None`` is appropriate if the class wishes to @@ -1484,7 +1484,7 @@ say that time objects don't participate in the :class:`tzinfo` protocols. It may be more useful for ``utcoffset(None)`` to return the standard UTC offset, as there is no other convention for discovering the standard offset. -When a :class:`datetime` object is passed in response to a :class:`datetime` +When a :class:`.datetime` object is passed in response to a :class:`.datetime` method, ``dt.tzinfo`` is the same object as *self*. :class:`tzinfo` methods can rely on this, unless user code calls :class:`tzinfo` methods directly. The intent is that the :class:`tzinfo` methods interpret *dt* as being in local @@ -1623,7 +1623,7 @@ made to civil time. .. method:: timezone.fromutc(dt) Return ``dt + offset``. The *dt* argument must be an aware - :class:`datetime` instance, with ``tzinfo`` set to ``self``. + :class:`.datetime` instance, with ``tzinfo`` set to ``self``. Class attributes: @@ -1637,18 +1637,18 @@ Class attributes: :meth:`strftime` and :meth:`strptime` Behavior ---------------------------------------------- -:class:`date`, :class:`datetime`, and :class:`time` objects all support a +:class:`date`, :class:`.datetime`, and :class:`.time` objects all support a ``strftime(format)`` method, to create a string representing the time under the control of an explicit format string. Broadly speaking, ``d.strftime(fmt)`` acts like the :mod:`time` module's ``time.strftime(fmt, d.timetuple())`` although not all objects support a :meth:`timetuple` method. Conversely, the :meth:`datetime.strptime` class method creates a -:class:`datetime` object from a string representing a date and time and a +:class:`.datetime` object from a string representing a date and time and a corresponding format string. ``datetime.strptime(date_string, format)`` is equivalent to ``datetime(*(time.strptime(date_string, format)[0:6]))``. -For :class:`time` objects, the format codes for year, month, and day should not +For :class:`.time` objects, the format codes for year, month, and day should not be used, as time objects have no such values. If they're used anyway, ``1900`` is substituted for the year, and ``1`` for the month and day. @@ -1806,5 +1806,5 @@ Notes: .. versionchanged:: 3.2 When the ``%z`` directive is provided to the :meth:`strptime` method, an - aware :class:`datetime` object will be produced. The ``tzinfo`` of the + aware :class:`.datetime` object will be produced. The ``tzinfo`` of the result will be set to a :class:`timezone` instance. |