Time

A talk about how to handle time and timezones. Given at Twente.rb

Transcript

1. Time
   Dirkjan Bussink!
   @dbussink
   

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2. Time is hard
   

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8. Basics
   

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10. Timezones
    

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11. http://momentjs.com/
    

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12. http://momentjs.com/
    

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13. Storing
    

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14. UTC
    

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15. Why?
    

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16. 2014-10-26 02:34
    

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17. A bit more!
    complicated
    

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18. Group!
    by date
    

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20. Who’s date?
    

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21. http://pellepim.bitbucket.org/jstz/
    

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24. Calculations
    

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26. Perspective
    

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28. UTC loses data
    

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29. UTC + offset
    

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30. 2014-08-19 16:12:50 +0200
    

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31. Time as a feature
    

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32. Calendars
    

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35. DST
    

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36. amsterdam = ActiveSupport::TimeZone["Europe/Amsterdam"]
    time = amsterdam.parse("2014-08-19 17:15")
    => Tue, 19 Aug 2014 17:15:00 CEST +02:00
    

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37. sydney = ActiveSupport::TimeZone[“Australia/Sydney"]
    !
    time
    => Tue, 19 Aug 2014 17:15:00 CEST +02:00
    time.in_time_zone(sydney)
    => Wed, 20 Aug 2014 01:15:00 EST +10:00
    

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38. later = time + 6.months
    => Thu, 19 Feb 2015 17:15:00 CET +01:00
    !
    later.in_time_zone(sydney)
    => Fri, 20 Feb 2015 03:15:00 EST +11:00
    

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39. Our recurring meeting!
    just moved 2 hours!
    

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40. UTC + offset!
    isn’t good enough
    

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41. Time & time zone
    Europe/Amsterdam
    Tue, 19 Aug 2014 17:15:00 CEST +02:00
    

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42. Time tracking
    

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43. Check in & check out
    

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44. 125%
    22:00 00:00
    150% Break 150%
    01:00 01:30 06:00
    

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45. DST
    

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46. 125% 150% Break 150%
    01:30 02:00 02:59
    02:00
    03:00
    

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47. 9 hours from 22:00 until 06:00
    

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48. Very specific!
    storage format
    

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49. Day!! ! ! ! ! ! ! 2014-10-26!
    Start!! ! ! ! ! ! 79200!! ! !
    End!! ! ! ! ! ! ! 108000!
    Duration!! ! 32400
    

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50. Take away
    

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51. Start with UTC
    

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52. Be careful!
    with timezones
    

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53. Make conscious!
    decisions
    

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