mxDateTime - Date and Time types for Python

Old History Entries

These are the really old history entries for those interested in how mxDateTime discovered the world of split seconds...

Things that changed from 0.8.4 to 0.9.0:

• Added oneWeek constant.

• Added ISO submodule for interfacing to ISO date and time representations.

• Added ISO.Week() constructor and .iso_week attribute to DateTime objects. (Hope I got that right...)

• Added gmticks method, a test to make sure ticks(offset,dst) always returns proper values for dst = 0 and dst = 1 and documentation on the possible error conditions that can occur when using these. The gmticks method is only available if the platform provides the timegm() C API. Currently, you will have to edit the Setup file to enable/disable the HAVE_TIMEGM compiler flag -- the next Python version (>1.5.1) will do the check for you.

• Fixed gmticks() to first try datetime.gmticks() and only revert to the ticks offset method if it is not available.

• Changed API for mktime(): the arguments are no longer defined as keywords and it now excepts three additional arguments to be call compatible to time.mktime().

• Added string parsing constructors to ISO that handle the most common cases of ISO string representation.

• Added ARPA submodule for parsing Internet dates.

Things that changed from 0.8.3 to 0.8.4:

• Added gmticks() and new parameters to the ticks()-method. This should make storing and retrieving UTC-time values a little easier.

Things that changed from 0.8.2 to 0.8.3:

• Fixed a small bugglet that caused the module not to compile with compilers that have problems with static forward declarations.

• Trimmed down the DateTime object size by a few bytes.

• Fixed the mxDateTime/__init__.py module to import all symbols from the extension module mxDateTime. This used to confuse some users.

Things that changed from 0.8.1 to 0.8.2:

• Added today().

• DateTime.tuple() now tries to determine the DST value assuming the stored value is given in local time.

• DateTime instances now have two extra attributes: datetime.dst is an integer stating if the given time uses DST or not and datetime.tz returns a timezone string.

• Reduced the pickle size for both types by providing function name shortcuts for the unpickling routines.

• The functions localtime() and gmtime() now return the current time rounded to the nearest micro-second. This makes un/pickling the current time more reliable (rounding errors become less likely).

• Added methods needed for the copy protocol as defined by the copy module: __copy__ and __deepcopy__. Since both types have immutable instances these functions merely return a new reference to the instance. Thanks to Stephane Bidoul for suggesting this addition.

• Fixed the documentation a little.

Things that changed from 0.8 to 0.8.1:

• Fixed a typo that caused conversion from DateTime to ticks using the ticks()-method to be off by one hour in summertime.

Things that changed from 0.7 to 0.8:

• Important change: Conversions from and to Unix time values (ticks) are now done assuming the broken down values represent local time, not UTC as in previous versions. now() returns local time instead of UTC -- this was confusing to some users. The change had to be done since I didn't want to carry the timemodule.c stuff all along the way... the method I used to convert from mktime() output to UTC was flaky anyway.

• Important for programmers wanting to use the C interface: I dropped the direct access macros in the mxDateTime header file. If you want to access the broken down representation of the instances from C, use the new DateTime[Delta]_BrokenDown() APIs. I did this, because I may decide to put the two types on a diet in a next version (i.e. dropping the cached broken down values).

• Added an alias 'Format' for the method DateTime.strftime. This makes the DateTime type compatible with the existing PythonWin date type.

• DateTime.strftime() defaults to '%c' as format string if no parameters are given.

• Dropped the plan to add keywords handling: it would produce a noticable performance hit due to the way keyword handling works in the interpreter.

• Dropped the module specific ConversionError in favour of the standard OverflowError. Conversion to ticks will raise an OverflowError in case the converted value doesn't fit into the machines time value format.

• Moved some constructors and objects from mxDateTime to DateTime. You won't notice any difference if you are using the DateTime interface (which you should), except the fact that some functions are now coded in Python rather than C.

• The TimeDelta() constructor now accepts keywords. This is a side-effect from moving it out of the C module into the Python package module. You can now write twoMinutes = TimeDelta(minutes=2).

• Added an experimental ODMG submodule that uses date/time classes built on top of the two basic types. The main difference is that they support timezone offsets.

• Added support for storing COM dates as-is. DateTimeFromCOMDate(x).COMDate() will always return x unchanged.

Things that changed from 0.6 to 0.7:

• To make the transition from usage of time values to usage of the new types easier, they can convert themselves to floats and integers on demand (e.g. with float() or int()). The DateTime instances return their value in ticks, the DateTimeDelta instances in seconds. The necessary conversion can cause a ConversionError to be raised in case the objects value doesn't fit into the converted types range.

• Since it is sometimes needed to have the date/time value stored in one number (begin sufficiently accurate to hold a vast range of dates), interfaces to both types were added that return the internal value as days Python float (maps to a C double). The fraction part is calculated using a 86400.0 seconds/day basis and does not account for leap seconds.

• Fixed a bug in the value of the constant Epoch. The epoch for this module is 1.1.0001 0:00:00.00 and not 1.1.0001 0:00:01.00.

• Added code from Modules/timemodule.c (found in the 1.5 Python distribution) that allows now() to return fractions of a second.

• Added __members__ attribute to both types. The builtin dir() function will now tell you what attributes the types have.

• The module now defines a cleanup function which it registers with Py_AtExit(). This will free the free lists upon finalization of the interpreter.

• Added #ifdefs and #defines to make the module more portable to platforms which don't provide the C lib functions strftime() and strptime(). These interfaces are only available on platforms which provide the corresponding C functions. You may have to enable them manually (see mxDateTime.c) on platforms other than Unix.

• When converting the date/time values to the representation used by the C API strftime(), seconds are now rounded to the next integer (the struct tm defines second as being an integer, thus fraction parts can not be displayed).

• Changed the default date/time representation for str() and repr() to ISO format. I previously used the strftime() C-API but that has the disadvantage of not displaying fractions of a second which can lead to representations off by up to 0.5 seconds.

• The second attributes of both types now return floats instead of integers.

Things that changed from 0.5 to 0.6:

• The constructor DateTimeDeltaFromTicks has been renamed to DateTimeDeltaFromSeconds, since the old name was misleading (ticks being a seconds since the epoch value). The corresponding C API's was dropped, since there already is a function providing the same functionality (DateTimeDelta_FromDaysAndSeconds with 0 days).

• The installation structure now uses a package layout. The package is called DateTime and imports the C extension mxDateTime.

• Fixed a bug causing overflow errors for larger deltas.

• Fixed a bugglet that prevented the module from being used inside packages.

• Fixed a naming bug in mxDateTime.h. The interface for DateTimeDelta now also uses function names without the 'mx' prefix. Changed DateTimeDelta_AsTicks to DateTimeDelta_AsDouble (see note above).

• The DateTimeDelta API now also provides low-level macros, like the DateTime API.

• Fixed a bug in DateTimeDelta() and in the str()/repr() routines that caused a core dump for very large deltas, e.g. DateTimeDeltaFromSeconds(-443243329200.0).

• Made the two types pickleable. Importing the package registers them via copy_reg.

• Added free lists for both types reducing the number of free/malloc calls necessary. If you don't want these lists, have a look at the top of the C file.

• Fixed a bug that caused comparing numbers and instances to always returned 0 (meaning equal).

Interface change from 0.4 to 0.5 (thanks to Greg Stein for suggesting many of these changes):

• The as_XXX methods have been renamed and some of them now return more information (that's why they were renamed, so an exception will be raised in case you still use them).

• Further attributes were added to DateTimeDelta objects. Because of this the method as_ticks and as_timetuple have been dropped.

• The DateTime constructor now takes arguments year, month, day, hour, minute, second instead of just absolute days and seconds. The old constructor is still available, but the name has been changed to DateTimeFromAbsDateTime().

• The constructors Date(), Time() and Timestamp() are just different names for DateTime(), TimeDelta(), DateTime() resp.

• The str() and repr() outputs have changed. These now use a format that should be usable in most standard situations.

• The DateTimeDelta attributes hour, minute, second now return negative values for negative time deltas.

The change index starts with version 0.4, the first one that also provided a type for time values.