DateTime 3.0b3

The DateTime package
====================

Encapsulation of date/time values.


Function Timezones()
--------------------

Returns the list of recognized timezone names:

>>> from DateTime import Timezones
>>> zones = set(Timezones())

Almost all of the standard pytz timezones are included, with the exception
of some commonly-used but ambiguous abbreviations, where historical Zope
usage conflicts with the name used by pytz:

>>> import pytz
>>> [x for x in pytz.all_timezones if x not in zones]
['CET', 'EET', 'EST', 'MET', 'MST', 'WET']

Class DateTime
--------------

DateTime objects represent instants in time and provide interfaces for
controlling its representation without affecting the absolute value of
the object.

DateTime objects may be created from a wide variety of string or
numeric data, or may be computed from other DateTime objects.
DateTimes support the ability to convert their representations to many
major timezones, as well as the ablility to create a DateTime object
in the context of a given timezone.

DateTime objects provide partial numerical behavior:

* Two date-time objects can be subtracted to obtain a time, in days
between the two.

* A date-time object and a positive or negative number may be added to
obtain a new date-time object that is the given number of days later
than the input date-time object.

* A positive or negative number and a date-time object may be added to
obtain a new date-time object that is the given number of days later
than the input date-time object.

* A positive or negative number may be subtracted from a date-time
object to obtain a new date-time object that is the given number of
days earlier than the input date-time object.

DateTime objects may be converted to integer, long, or float numbers
of days since January 1, 1901, using the standard int, long, and float
functions (Compatibility Note: int, long and float return the number
of days since 1901 in GMT rather than local machine timezone).
DateTime objects also provide access to their value in a float format
usable with the python time module, provided that the value of the
object falls in the range of the epoch-based time module.

A DateTime object should be considered immutable; all conversion and numeric
operations return a new DateTime object rather than modify the current object.

A DateTime object always maintains its value as an absolute UTC time,
and is represented in the context of some timezone based on the
arguments used to create the object. A DateTime object's methods
return values based on the timezone context.

Note that in all cases the local machine timezone is used for
representation if no timezone is specified.

Constructor for DateTime
------------------------

DateTime() returns a new date-time object. DateTimes may be created
with from zero to seven arguments:

* If the function is called with no arguments, then the current date/
time is returned, represented in the timezone of the local machine.

* If the function is invoked with a single string argument which is a
recognized timezone name, an object representing the current time is
returned, represented in the specified timezone.

* If the function is invoked with a single string argument
representing a valid date/time, an object representing that date/
time will be returned.

As a general rule, any date-time representation that is recognized
and unambigous to a resident of North America is acceptable. (The
reason for this qualification is that in North America, a date like:
2/1/1994 is interpreted as February 1, 1994, while in some parts of
the world, it is interpreted as January 2, 1994.) A date/ time
string consists of two components, a date component and an optional
time component, separated by one or more spaces. If the time
component is omited, 12:00am is assumed. Any recognized timezone
name specified as the final element of the date/time string will be
used for computing the date/time value. (If you create a DateTime
with the string "Mar 9, 1997 1:45pm US/Pacific", the value will
essentially be the same as if you had captured time.time() at the
specified date and time on a machine in that timezone).

o Returns current date/time, represented in US/Eastern:

>>> from DateTime import DateTime
>>> e = DateTime('US/Eastern')
>>> e.timezone()
'US/Eastern'

o Returns specified time, represented in local machine zone:

>>> x = DateTime('1997/3/9 1:45pm')
>>> x.parts() # doctest: +ELLIPSIS
(1997, 3, 9, 13, 45, 0.0, ...)

o Specified time in local machine zone, verbose format:

>>> y = DateTime('Mar 9, 1997 13:45:00')
>>> y.parts() # doctest: +ELLIPSIS
(1997, 3, 9, 13, 45, 0.0, ...)
>>> y == x
True

The date component consists of year, month, and day values. The
year value must be a one-, two-, or four-digit integer. If a one-
or two-digit year is used, the year is assumed to be in the
twentieth century. The month may an integer, from 1 to 12, a month
name, or a month abreviation, where a period may optionally follow
the abreviation. The day must be an integer from 1 to the number of
days in the month. The year, month, and day values may be separated
by periods, hyphens, forward, shashes, or spaces. Extra spaces are
permitted around the delimiters. Year, month, and day values may be
given in any order as long as it is possible to distinguish the
components. If all three components are numbers that are less than
13, then a a month-day-year ordering is assumed.

The time component consists of hour, minute, and second values
separated by colons. The hour value must be an integer between 0
and 23 inclusively. The minute value must be an integer between 0
and 59 inclusively. The second value may be an integer value
between 0 and 59.999 inclusively. The second value or both the
minute and second values may be ommitted. The time may be followed
by am or pm in upper or lower case, in which case a 12-hour clock is
assumed.

* If the DateTime function is invoked with a single Numeric argument,
the number is assumed to be either a floating point value such as
that returned by time.time() , or a number of days after January 1,
1901 00:00:00 UTC.

A DateTime object is returned that represents either the gmt value
of the time.time() float represented in the local machine's
timezone, or that number of days after January 1, 1901. Note that
the number of days after 1901 need to be expressed from the
viewpoint of the local machine's timezone. A negative argument will
yield a date-time value before 1901.

* If the function is invoked with two numeric arguments, then the
first is taken to be an integer year and the second argument is
taken to be an offset in days from the beginning of the year, in the
context of the local machine timezone. The date-time value returned
is the given offset number of days from the beginning of the given
year, represented in the timezone of the local machine. The offset
may be positive or negative. Two-digit years are assumed to be in
the twentieth century.

* If the function is invoked with two arguments, the first a float
representing a number of seconds past the epoch in gmt (such as
those returned by time.time()) and the second a string naming a
recognized timezone, a DateTime with a value of that gmt time will
be returned, represented in the given timezone.

>>> import time
>>> t = time.time()

Time t represented as US/Eastern:

>>> now_east = DateTime(t, 'US/Eastern')

Time t represented as US/Pacific:

>>> now_west = DateTime(t, 'US/Pacific')

Only their representations are different:

>>> now_east.equalTo(now_west)
True

* If the function is invoked with three or more numeric arguments,
then the first is taken to be an integer year, the second is taken
to be an integer month, and the third is taken to be an integer day.
If the combination of values is not valid, then a DateTimeError is
raised. One- or two-digit years up to 69 are assumed to be in the
21st century, whereas values 70-99 are assumed to be 20th century.
The fourth, fifth, and sixth arguments are floating point, positive
or negative offsets in units of hours, minutes, and days, and
default to zero if not given. An optional string may be given as
the final argument to indicate timezone (the effect of this is as if
you had taken the value of time.time() at that time on a machine in
the specified timezone).

If a string argument passed to the DateTime constructor cannot be
parsed, it will raise SyntaxError. Invalid date, time, or
timezone components will raise a DateTimeError.

The module function Timezones() will return a list of the timezones
recognized by the DateTime module. Recognition of timezone names is
case-insensitive.

Instance Methods for DateTime (IDateTime interface)
---------------------------------------------------

Conversion and comparison methods
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* ``timeTime()`` returns the date/time as a floating-point number in
UTC, in the format used by the python time module. Note that it is
possible to create date /time values with DateTime that have no
meaningful value to the time module, and in such cases a
DateTimeError is raised. A DateTime object's value must generally
be between Jan 1, 1970 (or your local machine epoch) and Jan 2038 to
produce a valid time.time() style value.

>>> dt = DateTime('Mar 9, 1997 13:45:00 US/Eastern')
>>> dt.timeTime()
857933100.0

>>> DateTime('2040/01/01 UTC').timeTime()
2208988800.0

>>> DateTime('1900/01/01 UTC').timeTime()
-2208988800.0

* ``toZone(z)`` returns a DateTime with the value as the current
object, represented in the indicated timezone:

>>> dt.toZone('UTC')
DateTime('1997/03/09 18:45:00 UTC')

>>> dt.toZone('UTC').equalTo(dt)
True

* ``isFuture()`` returns true if this object represents a date/time
later than the time of the call:

>>> dt.isFuture()
False
>>> DateTime('Jan 1 3000').isFuture() # not time-machine safe!
True

* ``isPast()`` returns true if this object represents a date/time
earlier than the time of the call:

>>> dt.isPast()
True
>>> DateTime('Jan 1 3000').isPast() # not time-machine safe!
False

* ``isCurrentYear()`` returns true if this object represents a
date/time that falls within the current year, in the context of this
object's timezone representation:

>>> dt.isCurrentYear()
False
>>> DateTime().isCurrentYear()
True

* ``isCurrentMonth()`` returns true if this object represents a
date/time that falls within the current month, in the context of
this object's timezone representation:

>>> dt.isCurrentMonth()
False
>>> DateTime().isCurrentMonth()
True

* ``isCurrentDay()`` returns true if this object represents a
date/time that falls within the current day, in the context of this
object's timezone representation:

>>> dt.isCurrentDay()
False
>>> DateTime().isCurrentDay()
True

* ``isCurrentHour()`` returns true if this object represents a
date/time that falls within the current hour, in the context of this
object's timezone representation:

>>> dt.isCurrentHour()
False

>>> DateTime().isCurrentHour()
True

* ``isCurrentMinute()`` returns true if this object represents a
date/time that falls within the current minute, in the context of
this object's timezone representation:

>>> dt.isCurrentMinute()
False
>>> DateTime().isCurrentMinute()
True

* ``isLeapYear()`` returns true if the current year (in the context of
the object's timezone) is a leap year:

>>> dt.isLeapYear()
False
>>> DateTime('Mar 8 2004').isLeapYear()
True

* ``earliestTime()`` returns a new DateTime object that represents the
earliest possible time (in whole seconds) that still falls within
the current object's day, in the object's timezone context:

>>> dt.earliestTime()
DateTime('1997/03/09 00:00:00 US/Eastern')

* ``latestTime()`` return a new DateTime object that represents the
latest possible time (in whole seconds) that still falls within the
current object's day, in the object's timezone context

>>> dt.latestTime()
DateTime('1997/03/09 23:59:59 US/Eastern')

Component access
~~~~~~~~~~~~~~~~

* ``parts()`` returns a tuple containing the calendar year, month,
day, hour, minute second and timezone of the object

>>> dt.parts()
(1997, 3, 9, 13, 45, 0.0, 'US/Eastern')

* ``timezone()`` returns the timezone in which the object is represented:

>>> dt.timezone() in Timezones()
True

* ``tzoffset()`` returns the timezone offset for the objects timezone:

>>> dt.tzoffset()
-18000

* ``year()`` returns the calendar year of the object:

>>> dt.year()
1997

* ``month()`` retursn the month of the object as an integer:

>>> dt.month()
3

* ``Month()`` returns the full month name:

>>> dt.Month()
'March'

* ``aMonth()`` returns the abreviated month name:

>>> dt.aMonth()
'Mar'

* ``pMonth()`` returns the abreviated (with period) month name:

>>> dt.pMonth()
'Mar.'

* ``day()`` returns the integer day:

>>> dt.day()
9

* ``Day()`` returns the full name of the day of the week:

>>> dt.Day()
'Sunday'

* ``dayOfYear()`` returns the day of the year, in context of the
timezone representation of the object:

>>> dt.dayOfYear()
68

* ``aDay()`` returns the abreviated name of the day of the week:

>>> dt.aDay()
'Sun'

* ``pDay()`` returns the abreviated (with period) name of the day of
the week:

>>> dt.pDay()
'Sun.'

* ``dow()`` returns the integer day of the week, where Sunday is 0:

>>> dt.dow()
0

* ``dow_1()`` returns the integer day of the week, where sunday is 1:

>>> dt.dow_1()
1

* ``h_12()`` returns the 12-hour clock representation of the hour:

>>> dt.h_12()
1

* ``h_24()`` returns the 24-hour clock representation of the hour:

>>> dt.h_24()
13

* ``ampm()`` returns the appropriate time modifier (am or pm):

>>> dt.ampm()
'pm'

* ``hour()`` returns the 24-hour clock representation of the hour:

>>> dt.hour()
13

* ``minute()`` returns the minute:

>>> dt.minute()
45

* ``second()`` returns the second:

>>> dt.second()
0.0

* ``millis()`` returns the milliseconds since the epoch in GMT.

>>> dt.millis()
857933100000L

strftime()
~~~~~~~~~~

See ``tests/testDateTime.py``.

General formats from previous DateTime
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* ``Date()`` return the date string for the object:

>>> dt.Date()
'1997/03/09'

* ``Time()`` returns the time string for an object to the nearest
second:

>>> dt.Time()
'13:45:00'

* ``TimeMinutes()`` returns the time string for an object not showing
seconds:

>>> dt.TimeMinutes()
'13:45'

* ``AMPM()`` returns the time string for an object to the nearest second:

>>> dt.AMPM()
'01:45:00 pm'

* ``AMPMMinutes()`` returns the time string for an object not showing
seconds:

>>> dt.AMPMMinutes()
'01:45 pm'

* ``PreciseTime()`` returns the time string for the object:

>>> dt.PreciseTime()
'13:45:00.000'

* ``PreciseAMPM()`` returns the time string for the object:

>>> dt.PreciseAMPM()
'01:45:00.000 pm'

* ``yy()`` returns the calendar year as a 2 digit string

>>> dt.yy()
'97'

* ``mm()`` returns the month as a 2 digit string

>>> dt.mm()
'03'

* ``dd()`` returns the day as a 2 digit string:

>>> dt.dd()
'09'

* ``rfc822()`` returns the date in RFC 822 format:

>>> dt.rfc822()
'Sun, 09 Mar 1997 13:45:00 -0500'

New formats
~~~~~~~~~~~

* ``fCommon()`` returns a string representing the object's value in
the format: March 9, 1997 1:45 pm:

>>> dt.fCommon()
'March 9, 1997 1:45 pm'

* ``fCommonZ()`` returns a string representing the object's value in
the format: March 9, 1997 1:45 pm US/Eastern:

>>> dt.fCommonZ()
'March 9, 1997 1:45 pm US/Eastern'

* ``aCommon()`` returns a string representing the object's value in
the format: Mar 9, 1997 1:45 pm:

>>> dt.aCommon()
'Mar 9, 1997 1:45 pm'

* ``aCommonZ()`` return a string representing the object's value in
the format: Mar 9, 1997 1:45 pm US/Eastern:

>>> dt.aCommonZ()
'Mar 9, 1997 1:45 pm US/Eastern'

* ``pCommon()`` returns a string representing the object's value in
the format Mar. 9, 1997 1:45 pm:

>>> dt.pCommon()
'Mar. 9, 1997 1:45 pm'

* ``pCommonZ()`` returns a string representing the object's value in
the format: Mar. 9, 1997 1:45 pm US/Eastern:

>>> dt.pCommonZ()
'Mar. 9, 1997 1:45 pm US/Eastern'

* ``ISO()`` returns a string with the date/time in ISO format. Note:
this is not ISO 8601-format! See the ISO8601 and HTML4 methods below
for ISO 8601-compliant output. Dates are output as: YYYY-MM-DD HH:MM:SS

>>> dt.ISO()
'1997-03-09 13:45:00'

* ``ISO8601()`` returns the object in ISO 8601-compatible format
containing the date, time with seconds-precision and the time zone
identifier - see http://www.w3.org/TR/NOTE-datetime. Dates are
output as: YYYY-MM-DDTHH:MM:SSTZD (T is a literal character, TZD is
Time Zone Designator, format +HH:MM or -HH:MM).

The ``HTML4()`` method below offers the same formatting, but
converts to UTC before returning the value and sets the TZD"Z"

>>> dt.ISO8601()
'1997-03-09T13:45:00-05:00'


* ``HTML4()`` returns the object in the format used in the HTML4.0
specification, one of the standard forms in ISO8601. See
http://www.w3.org/TR/NOTE-datetime. Dates are output as:
YYYY-MM-DDTHH:MM:SSZ (T, Z are literal characters, the time is in
UTC.):

>>> dt.HTML4()
'1997-03-09T18:45:00Z'

* ``JulianDay()`` returns the Julian day according to
http://www.tondering.dk/claus/cal/node3.html#sec-calcjd

>>> dt.JulianDay()
2450517

* ``week()`` returns the week number according to ISO
see http://www.tondering.dk/claus/cal/node6.html#SECTION00670000000000000000

>>> dt.week()
10

Deprecated API
~~~~~~~~~~~~~~

* DayOfWeek(): see Day()

* Day_(): see pDay()

* Mon(): see aMonth()

* Mon_(): see pMonth

General Services Provided by DateTime
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

DateTimes can be repr()'ed; the result will be a string indicating how
to make a DateTime object like this:

>>> `dt`
"DateTime('1997/03/09 13:45:00 US/Eastern')"

When we convert them into a string, we get a nicer string that could
actually be shown to a user:

>>> str(dt)
'1997/03/09 13:45:00 US/Eastern'

The hash value of a DateTime is based on the date and time and is
equal for different representations of the DateTime:

>>> hash(dt)
3618678
>>> hash(dt.toZone('UTC'))
3618678

DateTime objects can be compared to other DateTime objects OR floating
point numbers such as the ones which are returned by the python time
module by using the equalTo method. Using this API, True is returned if the
object represents a date/time equal to the specified DateTime or time module
style time:

>>> dt.equalTo(dt)
True
>>> dt.equalTo(dt.toZone('UTC'))
True
>>> dt.equalTo(dt.timeTime())
True
>>> dt.equalTo(DateTime())
False

Same goes for inequalities:

>>> dt.notEqualTo(dt)
False
>>> dt.notEqualTo(dt.toZone('UTC'))
False
>>> dt.notEqualTo(dt.timeTime())
False
>>> dt.notEqualTo(DateTime())
True

Normal equality operations only work with datetime objects and take the
timezone setting into account:

>>> dt == dt
True
>>> dt == dt.toZone('UTC')
False
>>> dt == DateTime()
False

>>> dt != dt
False
>>> dt != dt.toZone('UTC')
True
>>> dt != DateTime()
True

But the other comparison operations compare the referenced moment in time and
not the representation itself:

>>> dt > dt
False
>>> DateTime() > dt
True
>>> dt > DateTime().timeTime()
False
>>> DateTime().timeTime() > dt
True

>>> dt.greaterThan(dt)
False
>>> DateTime().greaterThan(dt)
True
>>> dt.greaterThan(DateTime().timeTime())
False

>>> dt >= dt
True
>>> DateTime() >= dt
True
>>> dt >= DateTime().timeTime()
False
>>> DateTime().timeTime() >= dt
True

>>> dt.greaterThanEqualTo(dt)
True
>>> DateTime().greaterThanEqualTo(dt)
True
>>> dt.greaterThanEqualTo(DateTime().timeTime())
False

>>> dt < dt
False
>>> DateTime() < dt
False
>>> dt < DateTime().timeTime()
True
>>> DateTime().timeTime() < dt
False

>>> dt.lessThan(dt)
False
>>> DateTime().lessThan(dt)
False
>>> dt.lessThan(DateTime().timeTime())
True

>>> dt <= dt
True
>>> DateTime() <= dt
False
>>> dt <= DateTime().timeTime()
True
>>> DateTime().timeTime() <= dt
False

>>> dt.lessThanEqualTo(dt)
True
>>> DateTime().lessThanEqualTo(dt)
False
>>> dt.lessThanEqualTo(DateTime().timeTime())
True

Numeric Services Provided by DateTime
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

A DateTime may be added to a number and a number may be added to a
DateTime:

>>> dt + 5
DateTime('1997/03/14 13:45:00 US/Eastern')
>>> 5 + dt
DateTime('1997/03/14 13:45:00 US/Eastern')

Two DateTimes cannot be added:

>>> dt + dt
Traceback (most recent call last):
...
DateTimeError: Cannot add two DateTimes

Either a DateTime or a number may be subtracted from a DateTime,
however, a DateTime may not be subtracted from a number:

>>> DateTime('1997/03/10 13:45 US/Eastern') - dt
1.0
>>> dt - 1
DateTime('1997/03/08 13:45:00 US/Eastern')
>>> 1 - dt
Traceback (most recent call last):
...
TypeError: unsupported operand type(s) for -: 'int' and 'DateTime'

DateTimes can also be converted to integers (number of seconds since
the epoch), longs (not too long ;)) and floats:

>>> int(dt)
857933100
>>> long(dt)
857933100L
>>> float(dt)
857933100.0


Changelog
=========

Backwards compatibility of DateTime 3
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

DateTime 3 changes its pickle representation. DateTime instances pickled with
former versions of DateTime can be read, but older DateTime versions cannot read
DateTime instances pickled with version 3.

DateTime 3 changes DateTime to be a new-style class with slots instead of being
an old-style class.

DateTime 3 tries to preserve microsecond resolution throughout most of its API's
while former versions were often only accurate to millisecond resolution. Due to
the representation of float values in Python versions before Python 2.7 you
shouldn't compare string or float representations of DateTime instances if you
want high accuracy. The same is true for calculated values returned by methods
like `timeTime()`. You get the highest accuracy of comparing DateTime values by
calling its `micros()` methods. DateTime is not particular well suited to be
used in comparing timestamps of file systems - use the time and datetime objects
from the Python standard library instead.

3.0b3 (2011-10-19)
------------------

- Allow comparison of DateTime objects against None.

3.0b2 (2011-10-19)
------------------

- Reverted the single argument `None` special case handling for unpickling and
continue to treat it as meaning `now`.

3.0b1 (2011-05-07)
------------------

- Restored `strftimeFormatter` as a class.

- Added tests for read-only class attributes and interface.

3.0a2 (2011-05-07)
------------------

- Added back support for reading old DateTime pickles without a `_micros` value.

- Avoid storing `_t` representing the time as a float in seconds since the
epoch, as we already have `_micros` doing the same as a long. Memory use is
down to about 300 bytes per DateTime instance.

- Updated exception raising syntax to current style.

- Avoid storing `_aday`, `_fday`, `_pday`, `_amon`, `_fmon`, `_pmon`, `_pmhour`
and `_pm` in memory for every instance but look them up dynamically based on
`_dayoffset`, `_month` and `_hour`. This saves another 150 bytes of memory
per DateTime instance.

- Moved various internal parsing related class variables to module constants.

- No longer provide the `DateError`, `DateTimeError`, `SyntaxError` and
`TimeError` exceptions as class attributes, import them from their canonical
`DateTime.interfaces` location instead.

- Removed deprecated `_isDST` and `_localzone` class variables.

- Moved pytz cache from `DateTime._tzinfo` to a module global `_TZINFO`.

- Make DateTime a new-style class and limit its available attributes via a
slots definition. The pickle size increases to 110 bytes thanks to the
`ccopy_reg\n_reconstructor` stanza. But the memory size drops from 3kb to
500 bytes for each instance.

3.0a1 (2011-05-06)
------------------

- Reordered some calculations in `_calcIndependentSecondEtc` to preserve more
floating point precision.

- Optimized the pickled data, by only storing a tuple of `_micros` and time
zone information - this reduces the pickle size from an average of 300 bytes
to just 60 bytes.

- Optimized un-pickling, by avoiding the creation of an intermediate DateTime
value representing the current time.

- Removed in-place migration of old DateTime pickles without a `_micros` value.

- Removed deprecated support for using `DateTime.__cmp__`.

- Take time zone settings into account when comparing two date times for
(non-) equality.

- Fixed (possibly unused) _parse_iso8601 function.

- Removed unused import of legacy DateTimeZone, strftime and re.
Remove trailing whitespace.

- Removed reference to missing version section from buildout.

2.12.6 (2010-10-17)
-------------------

- Changed ``testDayOfWeek`` test to be independent of OS locale.

2.12.5 (2010-07-29)
-------------------

- Launchpad #143269: Corrected the documentation for year value
behavior when constructing a DateTime object with three numeric
arguments.

- Launchpad #142521: Removed confusing special case in
DateTime.__str__ where DateTime instances for midnight
(e.g. '2010-07-27 00:00:00 US/Eastern') values would
render only their date and nothing else.

2.12.4 (2010-07-12)
-------------------

- Fixed mapping of EDT (was -> 'GMT-0400', now 'GMT-4').

2.12.3 (2010-07-09)
-------------------

- Added EDT timezone support. Addresses bug #599856.
[vangheem]

2.12.2 (2010-05-05)
-------------------

- Launchpad #572715: Relaxed pin on pytz, after applying a patch from
Marius Gedminus which fixes the apparent API breakage.

2.12.1 (2010-04-30)
-------------------

- Removed an undeclared testing dependency on zope.testing.doctest in favor of
the standard libraries doctest module.

- Added a maximum version requirement on pytz <= 2010b. Later versions produce
test failures related to timezone changes.

2.12.0 (2009-03-04)
-------------------

- Launchpad #290254: Forward-ported fix for '_micros'-less pickles from
the Zope 2.11 branch version.

2.11.2 (2009-02-02)
-------------------

- Include *all* pytz zone names, not just "common" ones.

- Fix one fragile doctest, band-aid another.

- Fix for launchpad #267545: DateTime(DateTime()) should preserve the
correct hour.

2.11.1 (2008-08-05)
-------------------

- DateTime conversion of datetime objects with non-pytz tzinfo. Timezones()
returns a copy of the timezone list (allows tests to run).

- Merged the slinkp-datetime-200007 branch: fix the DateTime(anotherDateTime)
constructor to preserve timezones.

2.11.0b1 (2008-01-06)
---------------------

- Split off from the Zope2 main source code tree.