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author | Xavier Noria <fxn@hashref.com> | 2010-08-06 17:29:52 +0200 |
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committer | Xavier Noria <fxn@hashref.com> | 2010-08-06 17:29:52 +0200 |
commit | 62bb83d0a27e83b0800e67676cfa0d0c47453f8e (patch) | |
tree | 881d86c5c63f7e9561eea581b97646d2ef254bd7 /railties/guides | |
parent | 3e678240f402fbf68cd25cc5daf1856ccb55f7cd (diff) | |
download | rails-62bb83d0a27e83b0800e67676cfa0d0c47453f8e.tar.gz rails-62bb83d0a27e83b0800e67676cfa0d0c47453f8e.tar.bz2 rails-62bb83d0a27e83b0800e67676cfa0d0c47453f8e.zip |
AS guide: documents calculations with Time objects
Diffstat (limited to 'railties/guides')
-rw-r--r-- | railties/guides/source/active_support_core_extensions.textile | 112 |
1 files changed, 99 insertions, 13 deletions
diff --git a/railties/guides/source/active_support_core_extensions.textile b/railties/guides/source/active_support_core_extensions.textile index d7d14236f6..9d9053d856 100644 --- a/railties/guides/source/active_support_core_extensions.textile +++ b/railties/guides/source/active_support_core_extensions.textile @@ -3053,30 +3053,30 @@ h4(#date-conversions). Conversions h3. Extensions to +DateTime+ -NOTE: All the following methods are defined in +active_support/core_ext/date_time/calculations.rb+. - WARNING: +DateTime+ is not aware of DST rules and so some of these methods have edge cases when a DST change is going on. For example +seconds_since_midnight+ might not return the real amount in such a day. h4(#calculations-datetime). Calculations +NOTE: All the following methods are defined in +active_support/core_ext/date_time/calculations.rb+. + The class +DateTime+ is a subclass of +Date+ so by loading +active_support/core_ext/date/calculations.rb+ you inherit these methods and their aliases, except that they will always return datetimes: <ruby> yesterday tomorrow -beginning_of_week -end_on_week +beginning_of_week (monday, at_beginning_of_week) +end_on_week (at_end_of_week) next_week months_ago months_since -beginning_of_month -end_of_month +beginning_of_month (at_beginning_of_month) +end_of_month (at_end_of_month) prev_month next_month -beginning_of_quarter -end_of_quarter -beginning_of_year -end_of_year +beginning_of_quarter (at_beginning_of_quarter) +end_of_quarter (at_end_of_quarter) +beginning_of_year (at_beginning_of_year) +end_of_year (at_end_of_year) years_ago years_since prev_year @@ -3086,10 +3086,10 @@ next_year The following methods are reimplemented so you do *not* need to load +active_support/core_ext/date/calculations.rb+ for these ones: <ruby> -beginning_of_day +beginning_of_day (midnight, at_midnight, at_beginning_of_day) end_of_day ago -since +since (in) </ruby> On the other hand, +advance+ and +change+ are also defined and support more options, they are documented below. @@ -3199,7 +3199,93 @@ h4(#datetime-conversions). Conversions h3. Extensions to +Time+ -... +h4(#time-calculations). Calculations + +NOTE: All the following methods are defined in +active_support/core_ext/date_time/calculations.rb+. + +Active Support adds to +Time+ many of the methods available for +DateTime+: + +<ruby> +past? +today? +future? +yesterday +tomorrow +seconds_since_midnight +change +advance +ago +since (in) +beginning_of_day (midnight, at_midnight, at_beginning_of_day) +end_of_day +beginning_of_week (monday, at_beginning_of_week) +end_on_week (at_end_of_week) +next_week +months_ago +months_since +beginning_of_month (at_beginning_of_month) +end_of_month (at_end_of_month) +prev_month +next_month +beginning_of_quarter (at_beginning_of_quarter) +end_of_quarter (at_end_of_quarter) +beginning_of_year (at_beginning_of_year) +end_of_year (at_end_of_year) +years_ago +years_since +prev_year +next_year +</ruby> + +They are analogous. Please refer to their documentation above and take into account the following differences: + +* +change+ accepts an additional +:usec+ option. +* +Time+ understands DST, so you get correct DST calculations as in + +<ruby> +# 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 +t.advance(:seconds => 1) +# => Sun Mar 28 03:00:00 +0200 2010 +</ruby> + +* If +since+ or +ago+ jump to a time that can't be expressed with +Time+ a +DateTime+ object is returned instead. + +h4. Time Constructors + +Active Support defines +Time.current+ to be +Time.zone.now+ if there's a user time zone defined, with fallback to +Time.now+: + +<ruby> +Time.zone_default +# => #<ActiveSupport::TimeZone:0x7f73654d4f38 @utc_offset=nil, @name="Madrid", ...> +Time.current +# => Fri, 06 Aug 2010 17:11:58 CEST +02:00 +</ruby> + +Analogously to +DateTime+, the predicates +past?+, and +future?+ are relative to +Time.current+. + +Use the +local_time+ class method to create time objects honoring the user time zone: + +<ruby> +Time.zone_default +# => #<ActiveSupport::TimeZone:0x7f73654d4f38 @utc_offset=nil, @name="Madrid", ...> +Time.local_time(2010, 8, 15) +# => Sun Aug 15 00:00:00 +0200 2010 +</ruby> + +The +utc_time+ class method returns a time in UTC: + +<ruby> +Time.zone_default +# => #<ActiveSupport::TimeZone:0x7f73654d4f38 @utc_offset=nil, @name="Madrid", ...> +Time.utc_time(2010, 8, 15) +# => Sun Aug 15 00:00:00 UTC 2010 +</ruby> + +Both +local_time+ and +utc_time+ accept up to seven positional arguments: year, month, day, hour, min, sec, usec. Year is mandatory, month and day default to 1, and the rest default to 0. + +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. h3. Extensions to +Process+ |