[issue1673409] datetime module missing some important methods
Alexander Belopolsky alexander.belopol...@gmail.com added the comment: With issue2706 accepted, I think this issue can now be rejected because proposed td.tosecs() can now be spelled simply as td/timedelta(seconds=1). The other RFE for a totimestamp() method is a duplicate of issue2736. -- nosy: +Alexander.Belopolsky, mark.dickinson -belopolsky ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Mark Dickinson dicki...@gmail.com added the comment: Closing this as a duplicate of issue 2736, as suggested. I'll combine the nosy lists. (BTW, as well as the newly introduced division methods, td.tosecs already exists, except that it's spelt td.total_seconds.) -- resolution: - duplicate status: open - closed superseder: - datetime needs an epoch method ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Alexander Belopolsky alexander.belopol...@gmail.com added the comment: On Wed, Apr 21, 2010 at 2:03 PM, Mark Dickinson rep...@bugs.python.org wrote: .. (BTW, as well as the newly introduced division methods, td.tosecs already exists, except that it's spelt td.total_seconds.) Aggrrr! How did that slip in? :-) 8639913600.0 Shouldn't td.total_seconds() return Decimal? Maybe in py4k ... -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Mark Dickinson dicki...@gmail.com added the comment: Aggrrr! How did that slip in? :-) Blame Antoine. :) (See issue 5788 and revision 76529.) Shouldn't td.total_seconds() return Decimal? Maybe in py4k ... Yes, that would have been nice. I'm not sure that the Decimal type is well-established enough yet that it's okay to return Decimal instances from random unrelated modules, though. Maybe someday. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Changes by Marc-Andre Lemburg m...@egenix.com: -- nosy: -lemburg ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Sebastian Rittau srit...@jroger.in-berlin.de added the comment: A timedelta.toseconds method (or equivalent) makes no sense. The number of seconds in a day is not fixed (due to leap seconds) and relying on such a method would introduce subtle bugs. The only way to find out the number of seconds in a range of dates is if you have a concrete date range. -- nosy: +srittau ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Changes by STINNER Victor victor.stin...@haypocalc.com: Removed file: http://bugs.python.org/file11919/timedelta_toseconds_float.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Jon Ribbens jribb...@users.sourceforge.net added the comment: A timedelta.toseconds method (or equivalent) makes no sense. The number of seconds in a day is not fixed (due to leap seconds) and relying on such a method would introduce subtle bugs. You are misunderstanding what timedelta is. It is a fixed-length period of time. It is stored as a number of (24x3600-second) days, seconds and microseconds. There is no start date or end date, so the concept of leap seconds just does not apply. ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
STINNER Victor victor.stin...@haypocalc.com added the comment: The number of seconds in a day is not fixed (due to leap seconds) POSIX timestamp doesn't count leap seconds. It looks like the datetime module is not aware of the leap seconds: print datetime.datetime(2006, 1, 1) - datetime.datetime(2005, 12, 31) 1 day, 0:00:00 About my method: I finally prefer datetime/datetime or datetime//datetime instead of a toseconds() method. And to convert a timestamp to a timestamp: see my patch attached to issue #2736. ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Antoine Pitrou pit...@free.fr added the comment: I also think totimestamp() on datetime objects would be useful, I've missed it myself a couple of times. The return value should be similar to that of time.time(), i.e. a float. -- nosy: +pitrou ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Sebastian Rittau srit...@jroger.in-berlin.de added the comment: Leap second handling is usually configurable. Default on Debian Linux (but similar on RHEL and SuSE): int(date(1994,1,1).strftime(%s)) - int(date(1993,1,1).strftime(%s)) 31536000 After doing cp /usr/share/zoneinfo/right/Europe/Berlin /etc/localtime: int(date(1994,1,1).strftime(%s)) - int(date(1993,1,1).strftime(%s)) 31536001 Also, NTP servers usually get this right. I don't think, Python should promote a wrong date handling by default, even if it's convenient. ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Antoine Pitrou pit...@free.fr added the comment: What you say is with 99500 days or more, the microsecond error is bigger than 90%. It means that with epoch starting at 1970, you can still return timestamps with a 1-2 microsecond accuracy for the year 2242. Additional precision would be overkill. ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
STINNER Victor victor.stin...@haypocalc.com added the comment: I removed my .toseconds() method patch because I prefer division. See issue #2706 for divison, divmod, etc. ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
STINNER Victor victor.stin...@haypocalc.com added the comment: (...) totimestamp() (...) return value should be similar to that of time.time(), i.e. a float float is a source of many problems (rounding problems), especially for huge values: float is unable to store correctly microseconds for big values: see msg75426. A simple tuple (int, int) is simple and there is no rounding/float limit. ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Changes by Brett Cannon br...@python.org: -- nosy: -brett.cannon ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
STINNER Victor [EMAIL PROTECTED] added the comment: (t - epoch) // timedelta(seconds=1) I don't like this syntax, because I can't guess the result unit: datetime - datetime - timedelta but: timedelta / timedelta - seconds? days? nanoseconds? If you example, you used timedelta(seconds=1), but what is the result unit if you use timedelta(hours=1)? or timedelta(days=1, microseconds=1)? The problem is that timedelta has no unit (or has multiple units), whereas timedelta.toseconds() are seconds. So about your example: (t - epoch).toseconds() -- fractional seconds int((t - epoch).toseconds()) -- whole seconds ___ Python tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Amaury Forgeot d'Arc [EMAIL PROTECTED] added the comment: timedelta / timedelta - seconds? days? nanoseconds? The quotient of two timedelta is a dimensionless number with no unit: timedelta(hours=1) / timedelta(minutes=5) == 12.0 This seems well defined, where is the ambiguity? -- nosy: +amaury.forgeotdarc ___ Python tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Alexander Belopolsky [EMAIL PROTECTED] added the comment: I was going to say the same as Amaury: timedelta / timedelta is dimensionless (time units cancel each other in division) and the advantage of this notation is that you get a way to express timedelta.toxxx for all units accepted in constructor and even toweeks becomes simple d / timedelta(7). I've started flashing out a patch and then recalled that I've seen one at issue2706 . So instead of attaching a new patch here, I am going to review the one in issue2706 now. There was also some related discussion at issue4291 . Apparently it has been suggested that timedelta to integer and float conversions would be a better alternative to timedelta / timedelta division. I disagree. Integer conversion is ambiguous - should it be to seconds, to microseconds or to timedelta.resolution (whatever that will become in the future)? Floating point conversion may loose precision as Tim pointed out in msg26266 . That would lead users to scratching their heads over what to use float(d1)/float(d2) or float(d1)/int(d2) or even int(d1)/int(d2) with true division on. This said, let's move this discussion to issue2706 now. On Fri, Nov 14, 2008 at 7:17 AM, Amaury Forgeot d'Arc [EMAIL PROTECTED] wrote: Amaury Forgeot d'Arc [EMAIL PROTECTED] added the comment: timedelta / timedelta - seconds? days? nanoseconds? The quotient of two timedelta is a dimensionless number with no unit: timedelta(hours=1) / timedelta(minutes=5) == 12.0 This seems well defined, where is the ambiguity? -- nosy: +amaury.forgeotdarc ___ Python tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 ___ ___ Python tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Alexander Belopolsky [EMAIL PROTECTED] added the comment: Chris I keep needing to know the number of seconds that a timedelta Chris represents. I propose an alternative approach that I believe will neatly solve fractional vs. whole seconds and multitude of conceivable toxxx methods: Let's extend timedelta's div and floordiv methods to allow (t - epoch) // timedelta(seconds=1) -- whole seconds and (t - epoch) / timedelta(seconds=1) -- fractional seconds -- nosy: +belopolsky ___ Python tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
STINNER Victor [EMAIL PROTECTED] added the comment: See also issue2736 ___ Python tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Steve Roberts [EMAIL PROTECTED] added the comment: I would like to add a use case, generating random dates. Especially generating random dates/times according to different probability distributions and within ranges. It would be nicest if operations could be done directly with datetime, date, time and timedelta objects, but easy conversion to and from timestamps as requested here would also make for reasonably convenient code (i.e. get timestamp conversions from objects to represent ranges, generate random numbers and convert back) -- nosy: +steve.roberts ___ Python tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Marc-Andre Lemburg [EMAIL PROTECTED] added the comment: You can have all this by using the time module's functions. It is true that these don't work for all dates, but they are still useful to have. FWIW: mxDateTime has always had methods to convert the date/time values to ticks and back again: http://www.egenix.com/products/python/mxBase/mxDateTime/ Since most of the datetime module was inspired by mxDateTime, I wonder why these were left out. -- nosy: +lemburg ___ Python tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Skip Montanaro [EMAIL PROTECTED] added the comment: Unassigning. Haven't heard from Tim in quite awhile and he's made no input on this issue. Also bump to 2.7. -- assignee: tim_one - versions: +Python 2.7 -Python 2.6 ___ Python tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
STINNER Victor [EMAIL PROTECTED] added the comment: I wrote this function is my program: def timedelta2seconds(delta): Convert a datetime.timedelta() objet to a number of second (floatting point number). timedelta2seconds(timedelta(seconds=2, microseconds=4)) 2.04 timedelta2seconds(timedelta(minutes=1, milliseconds=250)) 60.25 return delta.microseconds / 100.0 \ + delta.seconds + delta.days * 60*60*24 About the use cases: I use it to compute the compression rate of an audio song (bytes / seconds), to compute the bit rate of a video (bytes / seconds). I'm using datetime.timedelta() to store the audio/video duration. It's not related to time_t: see issue #2736 for datetime.datetime.totimestamp(). And about time_t: I don't about 31 bits signed integer. It's not beacuse other programs have arbitrary limits than Python should also be limited. About the patch: I don't like the name tosecs, it's not consistent with the constructor: timedelta(seconds=...).tosec[ond]s(). And why dropping the microseconds? For short duration, microseconds are useful. -- nosy: +haypo ___ Python tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Erik Stephens [EMAIL PROTECTED] added the comment: I'm not sure this is still being considered, so I just wanted to add my opinion. This seems like such a simple request being made overly complicated. We just want seconds since epoch since that is used in many other functions and libraries (i.e. the time module, os.stat().st_mtime). Why is there toordinal()?!? If there is going to be any toxxx() methods, there should definitely be a tosecs()/totimestamp() method or an 'epoch/timestamp' attribute. For boundary cases, I would look to the std time module for guidance. -- nosy: +erik.stephens ___ Python tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Chris AtLee added the comment: timedelta.todays() could be useful in general I suppose. I think timedelta.toweeks() could be omitted since it's simple division by an easy to recognize constant...also the timedelta docs say that it stores data in terms of microseconds, seconds, and days. OTOH tohours(), tominutes(), etc. (all the units that the constructor uses) could be useful in some cases. My feeling is that adding a method for each time unit bloats the API too much. Personally I've only ever wanted to know the number of seconds a timedelta represents. It seems like seconds are a good base unit to support since it allows easier interoperability with other python types and external data. _ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 _ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Skip Montanaro added the comment: Chris I keep needing to know the number of seconds that a timedelta Chris represents, so I implemented the following patch. I can sympathize, but if we accept this patch, for symmetry reasons shouldn't we also add .todays, .tomicroseconds and maybe even .toweeks? Skip _ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 _ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Chris AtLee added the comment:
I keep needing to know the number of seconds that a timedelta represents,
so I implemented the following patch.
This returns only the integer portion, but could be modified to return a
floating point value.
--
nosy: +catlee
Added file: http://bugs.python.org/file8837/timedelta.diff
_
Tracker [EMAIL PROTECTED]
http://bugs.python.org/issue1673409
_Index: Doc/library/datetime.rst
===
--- Doc/library/datetime.rst (revision 59236)
+++ Doc/library/datetime.rst (working copy)
@@ -266,7 +266,13 @@
efficient pickling, and in Boolean contexts, a :class:`timedelta` object is
considered to be true if and only if it isn't equal to ``timedelta(0)``.
+Instance methods:
+.. method:: timedelta.tosecs()
+
+ Returns the total number of seconds this timedelta object represents.
+ This is equivalent to (timedelta.days * 3600 * 24) + timedelta.seconds
+
.. _datetime-date:
:class:`date` Objects
Index: Lib/test/test_datetime.py
===
--- Lib/test/test_datetime.py (revision 59236)
+++ Lib/test/test_datetime.py (working copy)
@@ -475,6 +475,11 @@
self.assertEqual(str(t3), str(t4))
self.assertEqual(t4.as_hours(), -1)
+def test_tosecs(self):
+for s in (100, 1000, 1000, 1000):
+td = timedelta(seconds = s)
+self.assertEqual(td.tosecs(), s)
+
#
# date tests
Index: Modules/datetimemodule.c
===
--- Modules/datetimemodule.c (revision 59236)
+++ Modules/datetimemodule.c (working copy)
@@ -2058,6 +2058,28 @@
return Py_BuildValue(ON, Py_Type(self), delta_getstate(self));
}
+static PyObject *
+delta_tosecs(PyDateTime_Delta* self)
+{
+PyObject*t1, *t2;
+PyObject*days, *secs;
+PyObject*retval;
+
+t1 = PyLong_FromLong(GET_TD_DAYS(self));
+t2 = PyLong_FromLong(3600*24);
+days = PyNumber_Multiply(t1, t2);
+Py_DECREF(t1);
+Py_DECREF(t2);
+
+secs = PyLong_FromLong(GET_TD_SECONDS(self));
+
+retval = PyNumber_Add(days, secs);
+Py_DECREF(days);
+Py_DECREF(secs);
+
+return retval;
+}
+
#define OFFSET(field) offsetof(PyDateTime_Delta, field)
static PyMemberDef delta_members[] = {
@@ -2077,6 +2099,8 @@
{__reduce__, (PyCFunction)delta_reduce, METH_NOARGS,
PyDoc_STR(__reduce__() - (cls, state))},
+{tosecs, (PyCFunction)delta_tosecs, METH_NOARGS,
+ PyDoc_STR(Total number of seconds represented by this timedelta object.)},
{NULL, NULL},
};
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[issue1673409] datetime module missing some important methods
Jon Ribbens added the comment: No fractions of a second... If we're expecting floating-point, then everything you said earlier about the limitations of ints was a bit redundant ;-) _ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 _ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Tom Lazar added the comment: unless I'm missing something important this will do the trick quite nicely: from datetime import datetime datetime(2007, 12, 24, 20, 0).strftime(%s) '1198522800' For most imaginable use cases, where an epoch style time stamp is required this should be enough. HTH, Tom -- nosy: +tomster _ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 _ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Skip Montanaro added the comment: Tom unless I'm missing something important this will do the trick quite Tom nicely: from datetime import datetime datetime(2007, 12, 24, 20, 0).strftime(%s) Tom '1198522800' Tom For most imaginable use cases, where an epoch style time stamp is Tom required this should be enough. No fractions of a second... Skip _ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 _ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Skip Montanaro added the comment: One other thing worth noting is that %s is not universally available. Solaris, for example, lacks it in its strftime() implementation. (It has a bazillion other non-standard format strings but not %s.) Skip _ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 _ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Skip Montanaro added the comment: No fractions of a second... Jon If we're expecting floating-point, then everything you said earlier Jon about the limitations of ints was a bit redundant ;-) Yes, sorry. I responded to the mail without going back and reviewing the entire thread. (It's been a couple months.) Note however that my example to_timestamp() function converts the microseconds field to seconds and include them in the result. So, are we concluding that nothing needs to be added to the datetime module? Skip _ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 _ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Jon Ribbens added the comment: Well, I still think that a convert-to-time_t function is essential, and I don't buy any of the counter-arguments so far. The only argument I can see is should it return float or integer? - floats are inaccurate and integers can't represent partial seconds. _ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 _ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Brett Cannon added the comment: This is not going to go anywhere without someone offering a patch to implement this. Plus I suspect this has a much greater use in the C API than in the Python API for datetime. -- nosy: +brett.cannon _ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 _ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Jon Ribbens added the comment: Skip has already provided what amounts to a patch. It just needs to be decided whether to (a) not include it, (b) include it with the floating point part, or (c) include it without the floating point part. I couldn't comment as to how many people need it. I can say that I need it, and anyone else who's used to manipulating dates and times either in a unixy sort of way or with libraries that are expecting time_t's will need it. _ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 _ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Jon Ribbens added the comment: Almost everything you just said about time_t is wrong. time_t is signed, and always has been (otherwise the 'end of time' for 32-bit time_t would be 2106, not 2038). Also, time_t does not end at 2038 because nothing says it must be 32 bits. Also, Python has 'long integers' which do not overflow. Also, I don't understand what you mean about use cases. The use case is dealing with anything which expects standard Unix time_t, for example the Python standard library. The use case I have personally is the program I was working on when I encountered the problem described in this bug report. Also I think symmetry is a darn good argument. Why does fromtimestamp exist if, as you claim, nobody uses time_t? _ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 _ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Skip Montanaro added the comment: Jon Almost everything you just said about time_t is wrong. time_t is Jon signed, and always has been (otherwise the 'end of time' for 32-bit Jon time_t would be 2106, not 2038). Also, time_t does not end at 2038 Jon because nothing says it must be 32 bits. Also, Python has 'long Jon integers' which do not overflow. My apologies about goofing up on the signedness of time_t. What are you going to do with a long integer that you can't do with a datetime object? You clearly can't pass it directly to any Unix library functions which expect time_t. Converting it can overflow. Jon Also, I don't understand what you mean about use cases. The use Jon case is dealing with anything which expects standard Unix time_t, Jon for example the Python standard library. The use case I have Jon personally is the program I was working on when I encountered the Jon problem described in this bug report. Also I think symmetry is a Jon darn good argument. Why does fromtimestamp exist if, as you claim, Jon nobody uses time_t? What should datetime.datetime(, 1, 1).totimestamp() return? How would you pass it to something which accepts a time_t? The fromtimestamp functions work simply because the range of time_t is a proper subset of the range of Python's datetime objects. Symmetry gets you little. In situations where you need Unix timestamps and you know your datetime objects are within the bounds representable by time_t, you can define a convenience function: def totimestamp(dt): return time.mktime(dt.timetuple()) + dt.microsecond/1e6 This will, of course, fail if the year is too big or too small (and will fail in platform-dependent ways if the underlying platform's range of representable dates has different bounds than Unix does). Doing it without resorting to calling time.mktime is also nontrivial. Under the covers the datetime module currently uses platform functions to get time information anyway. It doesn't do a lot of low-level time arithmethic itself. Implementing fromtimestamp would require a fair amount of effort unless you were willing to punt and just raise OverflowError for dates outside the system's range. Skip _ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 _ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1673409] datetime module missing some important methods
Skip Montanaro added the comment: There is no datetime.totimestamp because the range of time represented by a datetime object far exceeds the range of a normal int-based Unix timestamp (roughly 1970-2038). Datetime objects before the start of the Unix epoch would be represented by negative numbers. As far as I know, the common Unix library functions which accept epoch times wouldn't know what to do with a negative number. That said, you stated these missing methods were important. Can you offer some use cases which would support that contention? I personally don't think a argument for symmetry would be a convincing use case and that's the only one I can think of. -- nosy: +skip.montanaro _ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue1673409 _ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
