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Daylight Savings?

 [1/4] from: ryan::christiansen::intellisol::com at: 18-Jun-2001 10:11


I worked up a function for finding out whether or not you are in Daylight Savings time in the United States. 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 _____________________________________ Confidentiality Notice This message may contain privileged and confidential information. If you think, for any reason, that this message may have been addressed to you in error, you must not disseminate, copy or take any action in reliance on it, and we would ask you to notify us immediately by return email to [ryan--christiansen--intellisol--com]

 [2/4] from: ryan:christiansen:intellisol at: 18-Jun-2001 10:20

Daylight Savings function


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 _____________________________________ Confidentiality Notice This message may contain privileged and confidential information. If you think, for any reason, that this message may have been addressed to you in error, you must not disseminate, copy or take any action in reliance on it, and we would ask you to notify us immediately by return email to [ryan--christiansen--intellisol--com]

 [3/4] from: jelinem1::nationwide::com at: 18-Jun-2001 14:39


I don't think I've ever made variable names (ie word names) that long before. Watch those line wraps! <tucks the Daylight Savings function away in his folder of REBOL tool-scripts> - Michael Jelinek

 [4/4] from: dness:home at: 19-Jun-2001 13:10


[ryan--christiansen--intellisol--com] wrote:
> 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. >
... Complex as it is, your function is a wild over-simplification of the `real' situation wrt DaylightSavings in the US. It may work well enough for most people's purposes, but it should be recognized that the real situation is quite `political' in nature, and that your code will produce the wrong answers for some places at some times...