Time

B012094b37ab6946c44eaa41d7828478?s=47 Dirkjan Bussink
February 10, 2015
Programming
0
41

 Time

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

B012094b37ab6946c44eaa41d7828478?s=128

Dirkjan Bussink

February 10, 2015
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Transcript

  1. 1.

    Time Dirkjan Bussink! @dbussink

  2. 2.

    Time is hard

  3. 3.
    None
  4. 4.
    None
  5. 5.
    None
  6. 6.
    None
  7. 7.
    None
  8. 8.

    Basics

  9. 9.
    None
  10. 10.

    Timezones

  11. 11.

    http://momentjs.com/

  12. 12.

    http://momentjs.com/

  13. 13.

    Storing

  14. 14.

    UTC

  15. 15.

    Why?

  16. 16.

    2014-10-26 02:34

  17. 17.

    A bit more! complicated

  18. 18.

    Group! by date

  19. 19.
    None
  20. 20.

    Who’s date?

  21. 21.

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

  22. 22.
    None
  23. 23.
    None
  24. 24.

    Calculations

  25. 25.
    None
  26. 26.

    Perspective

  27. 27.
    None
  28. 28.

    UTC loses data

  29. 29.

    UTC + offset

  30. 30.

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

  31. 31.

    Time as a feature

  32. 32.

    Calendars

  33. 33.
    None
  34. 34.
    None
  35. 35.

    DST

  36. 36.

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

    Aug 2014 17:15:00 CEST +02:00
  37. 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
  38. 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
  39. 39.

    Our recurring meeting! just moved 2 hours!

  40. 40.

    UTC + offset! isn’t good enough

  41. 41.

    Time & time zone Europe/Amsterdam Tue, 19 Aug 2014 17:15:00

    CEST +02:00
  42. 42.

    Time tracking

  43. 43.

    Check in & check out

  44. 44.

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

  45. 45.

    DST

  46. 46.

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

  47. 47.

    9 hours from 22:00 until 06:00

  48. 48.

    Very specific! storage format

  49. 49.

    Day!! ! ! ! ! ! ! 2014-10-26! Start!! !

    ! ! ! ! 79200!! ! ! End!! ! ! ! ! ! ! 108000! Duration!! ! 32400
  50. 50.

    Take away

  51. 51.

    Start with UTC

  52. 52.

    Be careful! with timezones

  53. 53.

    Make conscious! decisions