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gh-114728: Fix documentation for comparison of objects in datetime module #114749
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Original file line number | Diff line number | Diff line change |
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@@ -400,30 +400,7 @@ objects (see below). | |
the :func:`divmod` function. True division and multiplication of a | ||
:class:`timedelta` object by a :class:`float` object are now supported. | ||
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Comparisons of :class:`timedelta` objects are supported, with some caveats. | ||
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The comparisons ``==`` or ``!=`` *always* return a :class:`bool`, no matter | ||
the type of the compared object:: | ||
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>>> from datetime import timedelta | ||
>>> delta1 = timedelta(seconds=57) | ||
>>> delta2 = timedelta(hours=25, seconds=2) | ||
>>> delta2 != delta1 | ||
True | ||
>>> delta2 == 5 | ||
False | ||
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For all other comparisons (such as ``<`` and ``>``), when a :class:`timedelta` | ||
object is compared to an object of a different type, :exc:`TypeError` | ||
is raised:: | ||
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>>> delta2 > delta1 | ||
True | ||
>>> delta2 > 5 | ||
Traceback (most recent call last): | ||
File "<stdin>", line 1, in <module> | ||
TypeError: '>' not supported between instances of 'datetime.timedelta' and 'int' | ||
:class:`timedelta` objects support equality and order comparisons. | ||
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In Boolean contexts, a :class:`timedelta` object is | ||
considered to be true if and only if it isn't equal to ``timedelta(0)``. | ||
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@@ -606,8 +583,13 @@ Supported operations: | |
+-------------------------------+----------------------------------------------+ | ||
| ``timedelta = date1 - date2`` | \(3) | | ||
+-------------------------------+----------------------------------------------+ | ||
| ``date1 < date2`` | *date1* is considered less than *date2* when | | ||
| | *date1* precedes *date2* in time. (4) | | ||
| ``date1 == date2`` | Equality comparison. (4) | | ||
| ``date1 != date2`` | | | ||
+-------------------------------+----------------------------------------------+ | ||
| ``date1 < date2`` | Order comparison. (5) | | ||
| ``date1 > date2`` | | | ||
| ``date1 <= date2`` | | | ||
| ``date1 >= date2`` | | | ||
+-------------------------------+----------------------------------------------+ | ||
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Notes: | ||
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@@ -627,15 +609,20 @@ Notes: | |
timedelta.microseconds are 0, and date2 + timedelta == date1 after. | ||
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(4) | ||
:class:`date` objects are equal if they represent the same date. | ||
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:class:`!date` objects that are not also :class:`.datetime` instances | ||
are never equal to :class:`!datetime` objects, even if they represent | ||
the same date. | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Actually, this is not true. See #49766. |
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(5) | ||
*date1* is considered less than *date2* when *date1* precedes *date2* in time. | ||
In other words, ``date1 < date2`` if and only if ``date1.toordinal() < | ||
date2.toordinal()``. Date comparison raises :exc:`TypeError` if | ||
the other comparand isn't also a :class:`date` object. However, | ||
``NotImplemented`` is returned instead if the other comparand has a | ||
:attr:`~date.timetuple` attribute. This hook gives other kinds of date objects a | ||
chance at implementing mixed-type comparison. If not, when a :class:`date` | ||
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. | ||
date2.toordinal()``. | ||
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Order comparison between a :class:`!date` object that is not also a | ||
:class:`.datetime` instance and a :class:`!datetime` object raises | ||
:exc:`TypeError`. | ||
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In Boolean contexts, all :class:`date` objects are considered to be true. | ||
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@@ -1158,8 +1145,12 @@ Supported operations: | |
+---------------------------------------+--------------------------------+ | ||
| ``timedelta = datetime1 - datetime2`` | \(3) | | ||
+---------------------------------------+--------------------------------+ | ||
| ``datetime1 < datetime2`` | Compares :class:`.datetime` to | | ||
| | :class:`.datetime`. (4) | | ||
| ``datetime1 == datetime2`` | Equality comparison. (4) | | ||
+---------------------------------------+--------------------------------+ | ||
| ``datetime1 < datetime2`` | Order comparison. (5) | | ||
| ``datetime1 > datetime2`` | | | ||
| ``datetime1 <= datetime2`` | | | ||
| ``datetime1 >= datetime2`` | | | ||
+---------------------------------------+--------------------------------+ | ||
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(1) | ||
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@@ -1187,40 +1178,41 @@ Supported operations: | |
are done in this case. | ||
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If both are aware and have different :attr:`~.datetime.tzinfo` attributes, ``a-b`` acts | ||
as if *a* and *b* were first converted to naive UTC datetimes first. The | ||
as if *a* and *b* were first converted to naive UTC datetimes. The | ||
result is ``(a.replace(tzinfo=None) - a.utcoffset()) - (b.replace(tzinfo=None) | ||
- b.utcoffset())`` except that the implementation never overflows. | ||
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(4) | ||
:class:`.datetime` objects are equal if they represent the same date | ||
and time, taking into account the time zone. | ||
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Naive and aware :class:`!datetime` objects are never equal. | ||
:class:`!datetime` objects are never equal to :class:`date` objects | ||
that are not also :class:`!datetime` instances, even if they represent | ||
the same date. | ||
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If both comparands are aware and have different :attr:`~.datetime.tzinfo` | ||
attributes, the comparison acts as comparands were first converted to UTC | ||
datetimes except that the implementation never overflows. | ||
:class:`!datetime` instances in a repeated interval are never equal to | ||
:class:`!datetime` instances in other time zone. | ||
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(5) | ||
*datetime1* is considered less than *datetime2* when *datetime1* precedes | ||
*datetime2* in time. | ||
*datetime2* in time, taking into account the time zone. | ||
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If one comparand is naive and the other is aware, :exc:`TypeError` | ||
is raised if an order comparison is attempted. For equality | ||
comparisons, naive instances are never equal to aware instances. | ||
Order comparison between naive and aware :class:`.datetime` objects, | ||
as well as a :class:`!datetime` object and a :class:`!date` object | ||
that is not also a :class:`!datetime` instance, raises :exc:`TypeError`. | ||
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If both comparands are aware, and have the same :attr:`~.datetime.tzinfo` attribute, the | ||
common :attr:`~.datetime.tzinfo` attribute is ignored and the base datetimes are | ||
compared. If both comparands are aware and have different :attr:`~.datetime.tzinfo` | ||
attributes, the comparands are first adjusted by subtracting their UTC | ||
offsets (obtained from ``self.utcoffset()``). | ||
If both comparands are aware and have different :attr:`~.datetime.tzinfo` | ||
attributes, the comparison acts as comparands were first converted to UTC | ||
datetimes except that the implementation never overflows. | ||
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.. versionchanged:: 3.3 | ||
Equality comparisons between aware and naive :class:`.datetime` | ||
instances don't raise :exc:`TypeError`. | ||
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.. note:: | ||
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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, | ||
``NotImplemented`` is returned instead if the other comparand has a | ||
:attr:`~.datetime.timetuple` attribute. This hook gives other kinds of date objects a | ||
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. | ||
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Instance methods: | ||
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.. method:: datetime.date() | ||
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@@ -1754,21 +1746,18 @@ Instance attributes (read-only): | |
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.. versionadded:: 3.6 | ||
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:class:`.time` objects support 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 an order comparison is attempted. For equality | ||
comparisons, naive instances are never equal to aware instances. | ||
:class:`.time` objects support equality and order comparisons, | ||
where *a* is considered less than *b* when *a* precedes *b* in time. | ||
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Naive and aware :class:`!time` objects are never equal. | ||
Order comparison between naive and aware :class:`!time` objects raises | ||
:exc:`TypeError`. | ||
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If both comparands are aware, and have | ||
the same :attr:`~.time.tzinfo` attribute, the common :attr:`!tzinfo` attribute is | ||
ignored and the base times are compared. If both comparands are aware and | ||
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 | ||
different type, :exc:`TypeError` is raised unless the comparison is ``==`` or | ||
``!=``. The latter cases return :const:`False` or :const:`True`, respectively. | ||
subtracting their UTC offsets (obtained from ``self.utcoffset()``). | ||
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.. versionchanged:: 3.3 | ||
Equality comparisons between aware and naive :class:`.time` instances | ||
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