Update of /cvsroot/python/python/nondist/peps In directory sc8-pr-cvs1:/tmp/cvs-serv7859 Modified Files: pep-0000.txt Added Files: pep-0321.txt Log Message: Add PEP 321: Date/time parsing --- NEW FILE: pep-0321.txt --- PEP: 321 Title: Date/Time Parsing and Formatting Version: $Revision: 1.1 $ Last-Modified: $Date: 2003/09/16 12:07:56 $ Author: A.M. Kuchling <amk@amk.ca> Status: Draft Type: Standards Track Content-Type: text/x-rst Python-Version: 2.4 Created: 16-Sep-2003 Post-History: Abstract ======== Python 2.3 added a number of simple date and time types in the ``datetime`` module. There's no support for parsing strings in various formats and returning a corresponding instance of one of the types. This PEP proposes adding a family of predefined parsing function for several commonly used date and time formats, and a facility for generic parsing. The types provided by the ``datetime`` module all have ``.isoformat()`` and ``.ctime()`` methods that return string representations of a time, and the ``.strftime()`` method can be used to construct new formats. There are a number of additional commonly-used formats that would be useful to have as part of the standard library; this PEP also suggests how to add them. Input Formats ======================= Useful formats to support include `ISO8601`_, `RFC2822`_, `ctime`_, and some that are commonly written by humans such as the American "MM/DD/YYYY", the European "YYYY/MM/DD", and variants such as "DD-Month-YYYY". XXX The Perl `ParseDate.pm`_ module supports many different input formats, both absolute and relative. Should we try to support them all? Options: 1) Add functions to the ``datetime`` module:: import datetime d = datetime.parse_iso8601("2003-09-15T10:34:54") 2) Add class methods to the various types. There are already various class methods such as ``.now()``, so this would be pretty natural.:: import datetime d = datetime.date.parse_iso8601("2003-09-15T10:34:54") 3) Add a separate module (possible names: date, date_parse, parse_date) or subpackage (possible names: datetime.parser) containing parsing functions:: import datetime d = datetime.parser.parse_iso8601("2003-09-15T10:34:54") Unresolved questions: * Naming convention to use. * What exception to raise on errors? ValueError, or a specialized exception? * Should you know what type you're expecting, or should the parsing figure it out? (e.g. ``parse_iso8601("yyyy-mm-dd")`` returns a ``date`` instance, but parsing "yyyy-mm-ddThh:mm:ss" returns a ``datetime``.) Should there be an option to signal an error if a time is provided where none is expected, or if no time is provided? * Anything special required for I18N? For time zones? Generic Input Parsing ======================= Is a strptime() implementation that returns ``datetime`` types sufficient? XXX if yes, describe strptime here. Can the existing pure-Python implementation be easily retargeted? Output Formats ======================= Not all input formats need to be supported as output formats, because it's pretty trivial to get the ``strftime()`` argument right for simple things such as YYYY/MM/DD. Only complicated formats need to be supported; RFC2822 is currently the only one I can think of. Options: 1) Provide predefined format strings, so you could write this:: import datetime d = datetime.datetime(...) print d.strftime(d.RFC2822_FORMAT) # or datetime.RFC2822_FORMAT? 2) Provide new methods on all the objects:: d = datetime.datetime(...) print d.rfc822_time() References ========== .. _RFC2822: http://rfc2822.x42.com .. _ISO8601: http://www.cl.cam.ac.uk/~mgk25/iso-time.html .. _ParseDate.pm: http://search.cpan.org/author/MUIR/Time-modules-2003.0211/lib/Time/ParseDate... .. _ctime: http://www.opengroup.org/onlinepubs/007908799/xsh/asctime.html Other useful links: http://www.egenix.com/files/python/mxDateTime.html http://ringmaster.arc.nasa.gov/tools/time_formats.html http://www.thinkage.ca/english/gcos/expl/b/lib/0tosec.html Copyright ========= This document has been placed in the public domain.  .. Local Variables: mode: indented-text indent-tabs-mode: nil sentence-end-double-space: t fill-column: 70 End: Index: pep-0000.txt =================================================================== RCS file: /cvsroot/python/python/nondist/peps/pep-0000.txt,v retrieving revision 1.251 retrieving revision 1.252 diff -C2 -d -r1.251 -r1.252 *** pep-0000.txt 7 Sep 2003 13:56:12 -0000 1.251 --- pep-0000.txt 16 Sep 2003 12:07:56 -0000 1.252 *************** *** 117,120 **** --- 117,121 ---- S 318 Function/Method Decorator Syntax Smith S 319 Python Synchronize/Asynchronize Block Pelletier + S 321 Date/Time Parsing and Formatting Kuchling S 754 IEEE 754 Floating Point Special Values Warnes *************** *** 334,337 **** --- 335,339 ---- S 319 Python Synchronize/Asynchronize Block Pelletier I 320 Python 2.4 Release Schedule Warsaw + S 321 Date/Time Parsing and Formatting Kuchling SR 666 Reject Foolish Indentation Creighton S 754 IEEE 754 Floating Point Special Values Warnes