[REBOL] Daylight Savings function
From: ryan:christiansen:intellisol at: 18-Jun-2001 10:20
If you are in the United States in a location where Daylight Savings Time
is observed, here is a function to figure out whether or not you are in
Daylight Savings Time.
U.S._DaylightSavings?: func [
/local FirstSundayOfApril LastSundayOfOctober GMT GMT-based_U.S.
_DaylightSavingsBeginDate_CurrentYear GMT-based_U.S.
_DaylightSavingsEndDate_CurrentYear
][
FirstSundayOfApril: func [
year
][
make-begin-date: rejoin [{1-Apr-} year]
begin-date: make date! (make-begin-date)
either begin-date/weekday = 7 [
begin-date
][
until [
begin-date: begin-date + 1
begin-date/weekday = 7
]
begin-date
]
]
LastSundayOfOctober: func [
year
][
make-begin-date: rejoin [{31-Oct-} year]
begin-date: make date! (make-begin-date)
either begin-date/weekday = 7 [
begin-date
][
until [
begin-date: begin-date - 1
begin-date/weekday = 7
]
begin-date
]
]
GMT: now - now/zone
GMT-based_U.S._DaylightSavingsBeginDate_CurrentYear: FirstSundayOfApril
now/year
GMT-based_U.S._DaylightSavingsBeginDate_CurrentYear/time: 8:00:00
GMT-based_U.S._DaylightSavingsEndDate_CurrentYear: LastSundayOfOctober
now/year
GMT-based_U.S._DaylightSavingsEndDate_CurrentYear/time: 8:00:00
either all [(GMT > GMT-based_U.S.
_DaylightSavingsBeginDate_CurrentYear) (GMT < GMT-based_U.S.
_DaylightSavingsEndDate_CurrentYear)][
true
][
false
]
]
Ryan C. Christiansen
Web Developer
Intellisol International
4733 Amber Valley Parkway
Fargo, ND 58104
701-235-3390 ext. 6671
FAX: 701-235-9940
http://www.intellisol.com
Global Leader in People Performance Software
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