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#2525: update tzinfo example.

This commit is contained in:
Georg Brandl 2008-04-07 18:53:33 +00:00
parent a269762fb0
commit 45c2f778c4
1 changed files with 38 additions and 8 deletions
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46
Doc/lib/tzinfo-examples.py
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@ -87,11 +87,31 @@ def first_sunday_on_or_after(dt):
dt += timedelta(days_to_go)
return dt
# In the US, DST starts at 2am (standard time) on the first Sunday in April.
DSTSTART = datetime(1, 4, 1, 2)
# and ends at 2am (DST time; 1am standard time) on the last Sunday of Oct.
# which is the first Sunday on or after Oct 25.
DSTEND = datetime(1, 10, 25, 1)
# US DST Rules
#
# This is a simplified (i.e., wrong for a few cases) set of rules for US
# DST start and end times. For a complete and up-to-date set of DST rules
# and timezone definitions, visit the Olson Database (or try pytz):
# http://www.twinsun.com/tz/tz-link.htm
# http://sourceforge.net/projects/pytz/ (might not be up-to-date)
#
# In the US, since 2007, DST starts at 2am (standard time) on the second
# Sunday in March, which is the first Sunday on or after Mar 8.
DSTSTART_2007 = datetime(1, 3, 8, 2)
# and ends at 2am (DST time; 1am standard time) on the first Sunday of Nov.
DSTEND_2007 = datetime(1, 11, 1, 1)
# From 1987 to 2006, DST used to start at 2am (standard time) on the first
# Sunday in April and to end at 2am (DST time; 1am standard time) on the last
# Sunday of October, which is the first Sunday on or after Oct 25.
DSTSTART_1987_2006 = datetime(1, 4, 1, 2)
DSTEND_1987_2006 = datetime(1, 10, 25, 1)
# From 1967 to 1986, DST used to start at 2am (standard time) on the last
# Sunday in April (the one on or after April 24) and to end at 2am (DST time;
# 1am standard time) on the last Sunday of October, which is the first Sunday
# on or after Oct 25.
DSTSTART_1967_1986 = datetime(1, 4, 24, 2)
DSTEND_1967_1986 = DSTEND_1987_2006
class USTimeZone(tzinfo):
@ -122,9 +142,19 @@ class USTimeZone(tzinfo):
return ZERO
assert dt.tzinfo is self
# Find first Sunday in April & the last in October.
start = first_sunday_on_or_after(DSTSTART.replace(year=dt.year))
end = first_sunday_on_or_after(DSTEND.replace(year=dt.year))
# Find start and end times for US DST. For years before 1967, return
# ZERO for no DST.
if 2006 < dt.year:
dststart, dstend = DSTSTART_2007, DSTEND_2007
elif 1986 < dt.year < 2007:
dststart, dstend = DSTSTART_1987_2006, DSTEND_1987_2006
elif 1966 < dt.year < 1987:
dststart, dstend = DSTSTART_1967_1986, DSTEND_1967_1986
else:
return ZERO
start = first_sunday_on_or_after(dststart.replace(year=dt.year))
end = first_sunday_on_or_after(dstend.replace(year=dt.year))
# Can't compare naive to aware objects, so strip the timezone from
# dt first.