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diff --git a/doc/date/calendars.rdoc b/doc/date/calendars.rdoc deleted file mode 100644 index 4e6fd8334b..0000000000 --- a/doc/date/calendars.rdoc +++ /dev/null @@ -1,62 +0,0 @@ -== Julian and Gregorian Calendars - -The difference between the -{Julian calendar}[https://en.wikipedia.org/wiki/Julian_calendar] -and the -{Gregorian calendar}[https://en.wikipedia.org/wiki/Gregorian_calendar] -may matter to your program if it uses dates before the switchovers. - -- October 15, 1582. -- September 14, 1752. - -A date will be different in the two calendars, in general. - -=== Different switchover dates - -The reasons for the difference are religious/political histories. - -- On October 15, 1582, several countries changed - from the Julian calendar to the Gregorian calendar; - these included Italy, Poland, Portugal, and Spain. - Other countries in the Western world retained the Julian calendar. -- On September 14, 1752, most of the British empire - changed from the Julian calendar to the Gregorian calendar. - -When your code uses a date before these switchover dates, -it will matter whether it considers the switchover date -to be the earlier date or the later date (or neither). - -See also {a concrete example here}[rdoc-ref:DateTime@When+should+you+use+DateTime+and+when+should+you+use+Time-3F]. - -=== Argument +start+ - -Certain methods in class \Date handle differences in the -{Julian and Gregorian calendars}[rdoc-ref:date/calendars.rdoc@Julian+and+Gregorian+Calendars] -by accepting an optional argument +start+, whose value may be: - -- Date::ITALY (the default): the created date is Julian - if before October 15, 1582, Gregorian otherwise: - - d = Date.new(1582, 10, 15) - d.prev_day.julian? # => true - d.julian? # => false - d.gregorian? # => true - -- Date::ENGLAND: the created date is Julian if before September 14, 1752, - Gregorian otherwise: - - d = Date.new(1752, 9, 14, Date::ENGLAND) - d.prev_day.julian? # => true - d.julian? # => false - d.gregorian? # => true - -- Date::JULIAN: the created date is Julian regardless of its value: - - d = Date.new(1582, 10, 15, Date::JULIAN) - d.julian? # => true - -- Date::GREGORIAN: the created date is Gregorian regardless of its value: - - d = Date.new(1752, 9, 14, Date::GREGORIAN) - d.prev_day.gregorian? # => true - |
