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AS guide: documents date/datetime/time arithmetic with durations

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Xavier Noria 2010-08-10 01:30:37 +02:00
parent 394f4c9679
commit 898bd38d7a
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railties/guides/source/active_support_core_extensions.textile
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@ -3009,6 +3009,26 @@ Date.new(2010, 1, 31).change(:month => 2)
# => ArgumentError: invalid date
</ruby>
h5. Durations
Durations can be added and substracted to dates:
<ruby>
d = Date.current
# => Mon, 09 Aug 2010
d + 1.year
# => Tue, 09 Aug 2011
d - 3.hours
# => Sun, 08 Aug 2010 21:00:00 UTC +00:00
</ruby>
They translate to calls to +since+ or +advance+. For example here we get the correct jump in the calendar reform:
<ruby>
Date.new(1582, 10, 4) + 1.day
# => Fri, 15 Oct 1582
</ruby>
h5. Timestamps
INFO: The following methods return a +Time+ object if possible, otherwise a +DateTime+. If set, they honor the user time zone.
@ -3195,7 +3215,25 @@ DateTime.current.change(:month => 2, :day => 30)
# => ArgumentError: invalid date
</ruby>
h4(#datetime-conversions). Conversions
h5. Durations
Durations can be added and substracted to datetimes:
<ruby>
now = DateTime.current
# => Mon, 09 Aug 2010 23:15:17 +0000
now + 1.year
# => Tue, 09 Aug 2011 23:15:17 +0000
now - 1.week
# => Mon, 02 Aug 2010 23:15:17 +0000
</ruby>
They translate to calls to +since+ or +advance+. For example here we get the correct jump in the calendar reform:
<ruby>
DateTime.new(1582, 10, 4, 23) + 1.hour
# => Fri, 15 Oct 1582 00:00:00 +0000
</ruby>
h3. Extensions to +Time+
@ -3243,6 +3281,9 @@ They are analogous. Please refer to their documentation above and take into acco
* +Time+ understands DST, so you get correct DST calculations as in
<ruby>
Time.zone_default
# => #<ActiveSupport::TimeZone:0x7f73654d4f38 @utc_offset=nil, @name="Madrid", ...>
# In Barcelona, 2010/03/28 02:00 +0100 becomes 2010/03/28 03:00 +0200 due to DST.
t = Time.local_time(2010, 3, 28, 1, 59, 59)
# => Sun Mar 28 01:59:59 +0100 2010
@ -3287,6 +3328,26 @@ Both +local_time+ and +utc_time+ accept up to seven positional arguments: year,
If the time to be constructed lies beyond the range supported by +Time+ in the runtime platform, usecs are discarded and a +DateTime+ object is returned instead.
h5. Durations
Durations can be added and substracted to time objects:
<ruby>
now = Time.current
# => Mon, 09 Aug 2010 23:20:05 UTC +00:00
now + 1.year
# => Tue, 09 Aug 2011 23:21:11 UTC +00:00
now - 1.week
# => Mon, 02 Aug 2010 23:21:11 UTC +00:00
</ruby>
They translate to calls to +since+ or +advance+. For example here we get the correct jump in the calendar reform:
<ruby>
Time.utc_time(1582, 10, 3) + 5.days
# => Mon Oct 18 00:00:00 UTC 1582
</ruby>
h3. Extensions to +Process+
...