PEP 321: Date/Time Parsing and Formatting

[A.M. Kuchling]

On Mon, 17 Nov 2003 18:55:20 +0100, 
	Gerrit Holl <gerrit at nl.linux.org> wrote:
> I think there should be a 'strptime' equivalent, on which the former
> three input formats are build. I think the latter should be a class
> method of Timedelta. Then, those examples would be used as such:

There's already a _strptime module used internally by time.strptime().  It
wouldn't be difficult to rearrange the module a little to have functions
that returned datetime instances.

Let's assume we add a strptime() method to date, time, and datetime. What
happens when you provide a time or date where it's not useful e.g.
date.strptime(..., '1992-10-15 12:05:32')?  Does it raise an exception? Does
it silently ignore the time data?  Or is it illegal to use time-related
specifiers such as %H with date.strptime, or date-related ones such as %m
with time.strptime?

> I prefer solution 2. I think it is the most object-oriented way. And we

So do we have one parsing method -- strptime() -- or several, one for each
variant date format?  Perhaps the simplest thing is to just add strptime()
for now.

> though. Shouldn't datetime be a subclass of both date and time?

Probably not; a time represents a time independent of any particular day, 
while a datetime is certainly tied to a day, so a subclass relationship
doesn't make sense.

I'm lukewarm about CVS or tar-style times ("12 hours ago" "yesterday"). They
may be good command-line user interface, because you don't need to look up
the current time and then figure out what time 18 hours ago was, but writing
such command-line UIs probably isn't very common.

--amk