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A Tale about Time @hannesvdvreken @phpday
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Hi, my name is Hannes.
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This is a 50 minute talk in 25 minutes.
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“We'd like to start the happy hour 30 minutes earlier than previously planned … and the best solution would be to move your talk”
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EDT = UTC-04:00 CEST = UTC+02:00
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EDT = UTC-04:00 CEST = UTC+02:00
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# UTC+05:30
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UTC+05:45 $
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DST CET/CEST
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Helsinki Sunrise: 9:24 - 3:54 Sunset: 15:13 - 22:50 Quito Sunrise: 6:08 - 6:12 Sunset: 18:16 - 18:19
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EST/EDT - March 12 CET/CEST - March 24
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%
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&/'
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Calendars
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Weeks - 7 days Starts on Monday. Or Sunday? First week of the year?
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Months Lunar vs Tropical
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Years Lunisolar vs Tropical
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2018AD 1500BC
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Leap years
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Leap years Leap seconds
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Storing vs Expressing time
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Expressing time: 6:00PM vs 18:00
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Expressing time: May 12 12/05/2018
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Storing time: 1521261900
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Storing time: 1521261900 >1970-01-01T00:00:00+00:00
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Storing time: 1521261900 >1970-01-01T00:00:00+00:00 <2038-01-19T03:14:07+00:00 (32bit)
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Storing time: RFC3339: 2018-03-17T10:15:00+05:30
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Storing time: RFC3339 extended: 2018-03-17T10:15:00.000+05:30
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Storing time: Sortable (in UTC): 2018-03-17T05:45:00.000+00:00
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Storing time: Sortable (in UTC): 2018-03-17T05:45:00.000+00:00 + user’s location for timezone & locale
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Time in PHP
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DateTimeInterface - DateTime (date, time, tz) - DateTimeImmutable
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$date = DateTimeImmutable::createFromMutable($mutable);
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Change in PHP 7.1: microseconds
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$date = $date->setTimezone('Europe/Rome');
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// Magic $date = new DateTimeImmutable('now'); $date = $date->modify('first day of next month');
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“now + 5 hours” “first day of next month” "first weekday” …
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“2016-03-00” → “2016-02-29” “2018-06-31” → “2018-07-01” …
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“69-12-31” → “2069-12-31” “70-01-01” → “1970-01-01” …
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nesbot/carbon - Mutable cakephp/chronos - Immutable
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interface Clock { public function now(): DateTimeImmutable }
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The future
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E=mc²
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c ~ 299.000.000m/s
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(new DateTimeImmutable(‘now’)) ->setPlanet(new Planet(‘mars’));
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Wrapping up
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Thanks for your time! @hannesvdvreken @phpday
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Time for questions. @hannesvdvreken @phpday