Guido has in mind an easier way for users to code this stuff, but the
only tests we have now are for fixed-offset tzinfo classes, and this
stuff is extremely delicate in the endcases (read the new test code
for why: there are holes in time <wink>).
operands have identical tzinfo members (meaning object identity -- "is").
I misunderstood the intent here, reading wrong conclusion into
conflicting clues.
subtraction, work as documented. In the Python implementation,
they weren't calling utcoffset() if both operands had the same
tzinfo object. That's fine if it so happens that the shared
tzinfo object returns a fixed offset (independent of operand),
but can give wrong results if that's not so, and the latter
obtains in a tzinfo subclass instance trying to model both
standard and daylight times. The C implementation was already
doing this "correctly", so we're just adding tests to verify it.
be trusted with years before 1900, so now we raise ValueError if a date or
datetime or datetimetz .strftime() method is called with a year before
1900.
{timetz,datetimetz}.{utcoffset,dst}() now return a timedelta (or None)
instead of an int (or None).
tzinfo.{utcoffset,dst)() can now return a timedelta (or an int, or None).
Curiously, this was much easier to do in the C implementation than in the
Python implementation (which lives in the Zope3 code tree) -- the C code
already had lots of hair to extract C ints from offset objects, and used
C ints internally.
used that.
wrap_strftime(): Removed the most irritating uses of buf.
TestDate.test_ordinal_conversions(): The C implementation is fast enough
that we can afford to check the endpoints of every year. Also added
tm_yday tests at the endpoints.
Tim Peters