[Python-bugs-list] [ python-Bugs-665194 ] datetime-RFC2822 roundtripping

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Bugs item #665194, was opened at 2003-01-09 13:24
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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=665194&group_id=5470

Category: None
Group: Feature Request
Status: Open
Resolution: None
Priority: 5
Submitted By: Walter Dörwald (doerwalter)
Assigned to: Nobody/Anonymous (nobody)
Summary: datetime-RFC2822 roundtripping

Initial Comment:
It would be good to have a simply way to convert
between datetime objects and RFC2822 style strings.
>From string to datetime is easy with
datetime.datetime(*email.Utils.parsedate(m)[:7]) (but
this drops the timezone), but the other direction seems
impossible. email.Utils.formatdate takes a timestamp
argument, but AFAICT there's no way to get a timestamp
out of a datetime object.

Of course the best solution (ignoring backwards
compatibility) would be for parsedate und formatdate to
return/accept datetime objects or for datetime to have
the appropriate methods.

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>Comment By: Tim Peters (tim_one)
Date: 2003-01-11 11:32

Message:
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Define what totimestamp() should do.  The range of 
timestamps supported by the *platform* C library (and so 
indirectly by Python's time module) isn't defined by any 
standard, and isn't easily discoverable either.  It may or 
may not work before 1970, may or may not after 2038.  
datetime covers days far outside that range.  Note that 
even a double doesn't have enough bits of precision to 
cover the full range of datetime values, either.

In contrast, ordinals are wholly under Python's control, so 
we can promise surprise-free conversion in both directions.  
All we can promise about timestamps is that if the platform 
supports a timestamp for a time in datetime's range, 
datetime can make sense of it.

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Comment By: Walter Dörwald (doerwalter)
Date: 2003-01-11 07:33

Message:
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OK, I'll mark this a feature request.

datetime has fromordinal() and toordinal(), it has 
fromtimestamp(), so I'd say a totimestamp() method would be 
a logical addition.

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Comment By: Tim Peters (tim_one)
Date: 2003-01-11 00:10

Message:
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You can get a timestamp like so:

>>> time.mktime(datetime.date(2002, 1, 1).timetuple())
1009861200.0
>>>

The dates for which this works depends on the platform 
mktime implementation, though.

BTW, this sounds a lot more like a new feature request 
than a bug!

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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=665194&group_id=5470