date2 - An alternative date class
Date
Terms and definitions
Some terms and definitions are based on ISO 8601 and JIS X 0301.
calendar date
The calendar date is a particular day of a calendar year, identified
by its ordinal number within a calendar month within that year.
ordinal date
The ordinal date is a particular day of a calendar year identified by
its ordinal number within the year.
week date
The week date is a date identified by calendar week and day numbers.
The calendar week is a seven day period within a calendar year,
starting on a Monday and identified by its ordinal number within the
year; the first calendar week of the year is the one that includes the
first Thursday of that year. In the Gregorian calendar, this is
equivalent to the week which includes January 4.
julian day number
The Julian day number is in elapsed days since noon (Greenwich mean
time) on January 1, 4713 BCE (in the Julian calendar).
In this document, the astronomical Julian day number is same as the
original Julian day number. And the chronological Julian day number is
a variation of the Julian day number. Its days begin at midnight on
local time.
In this document, when the term "Julian day number" simply appears, it
just refers to "chronological Julian day number", not the original.
modified julian day number
The modified Julian day number is in elapsed days since midnight
(Coordinated universal time) on November 17, 1858 CE (in the Gregorian
calendar).
In this document, the astronomical modified Julian day number is same
as the original modified Julian day number. And the chronological
modified Julian day number is a variation of the modified Julian day
number. Its days begin at midnight on local time.
In this document, when the term "modified Julian day number" simply
appears, it just refers to "chronological modified Julian day number",
not the original.
Super Class
Object
Included Modules
Comparable
Class Methods
civil([year[, mon[, mday[, start]]]])
new([year[, mon[, mday[, start]]]])
Creates a date object denoting the given calendar date.
In this class, BCE years are counted astronomically. Thus, the
year before the year 1 is the year zero, and the year preceding
the year zero is the year -1. The month and the day of month
should be a negative or a positive number (reverse order when
negative). They should not be zero.
The last argument should be a Julian day number which denotes
the first day of the Gregorian calendar. You can also give true
which mean the proleptic Gregorian calendar, and false which
mean the proleptic Julian calendar. Default is Date::ITALY
(October 15, 1582).
See also jd.
commercial([cwyear[, cweek[, cwday[, start]]]])
Creates a date object denoting the given week date.
The week and the day of week should be a negative or a positive
number (reverse order when negative). They should not be zero.
This method does not accept dates before the day of calendar
reform.
See also jd and new.
jd ([jd[, start]])
Creates a date object denoting the given Julian day number.
In this class, some important methods do not accept negative
Julian day numbers.
See also new.
ordinal([year[, yday[, start]]])
Creates a date object denoting the given ordinal date.
The day of year should be a negative or a positive number
(reverse order when negative). It should not be zero.
See also jd and new.
parse(str[, complete[, start]])
Parses the given representation of dates and times, and creates
a date object.
If the optional second argument is true and the detected year
is in the range 0 to 99, considers the year a 2-digit form and
makes it full. Default is false.
_parse is also available. This method is similar to parse, but
returns a hash which contain detected elements, not creates a
date object.
strptime(str[, format[, start]])
Parses the given representation of dates and times with the
given template, and creates a date object.
_strptime is also available. This method is similar to
strptime, but returns a hash which contain detected elements,
not creates a date object.
See also strptime(3) and strftime.
today([start])
Creates a date object denoting the present day.
valid_civil? (year, mon, mday[, start])
valid_date? (year, mon, mday[, start])
Returns a Julian day number if the given calendar date is
valid, and nil if not.
See also jd and civil.
valid_commercial? (cwyear, cweek, cwday[, start])
Returns a Julian day number if the given week date is valid,
and nil if not.
See also jd and commercial.
valid_jd? (jd[, start])
Just returns the first argument immediately.
It's nonsense, but is for symmetry.
See also jd.
valid_ordinal? (year, yday[, start])
Returns a Julian day number if the given ordinal date is valid,
and nil if not.
See also jd and ordinal.
Methods
self + n
Returns a date object pointing n days after self. The n should
be a numeric value.
self - x
Returns the difference between the two dates if the x is a date
object. If the x is a numeric value, it returns a date object
pointing x days before self.
self << n
Returns a date object pointing n months before self. The n
should be a numeric value.
self <=> other
Compares the two dates and returns -1, zero or 1. The other
should be a date object or a numeric value as an astronomical
Julian day number.
self === other
Returns true if they are the same day.
self >> n
Returns a date object pointing n months after self. The n
should be a numeric value.
asctime
ctime
Returns a string in asctime(3) format (but without "\n\0" at
the end).
cwday
Returns the day of calendar week (1-7, Monday is 1).
cweek
Returns the calendar week number (1-53).
cwyear
Returns the calendar week based year.
downto(min){|date| ...}
This method is equivalent to step(min, -1){|date| ...}.
england
This method is equivalent to new_start(Date::ENGLAND).
gregorian
This method is equivalent to new_start(Date::GREGORIAN).
italy
This method is equivalent to new_start(Date::ITALY).
jd
Returns the Julian day number. It has no time of the day.
rjd is also available. This method is similar to jd, but
returns the astronomical Julian day number. It may have time of
the day.
julian
This method is equivalent to new_start(Date::JULIAN).
leap?
Returns true if the year is a leap year.
mday
day
Returns the day of month (1-31).
mjd
Returns the modified Julian day number. It has no time of the
day.
rmjd is also available. This method is similar to mjd, but
returns the astronomical modified Julian day number. It may
have time of the day.
mon
month
Returns the month (1-12).
new_start([start])
Duplicates self and resets the its first day of the Gregorian
calendar. Default is Date::ITALY (October 15, 1582).
See also new.
start
Returns a Julian day number denoting the first day of the
Gregorian calendar.
See also new.
step(limit, step){|date| ...}
Iterates evaluation of the given block, which takes a date
object. The limit should be a date object, and the step should
be a nonzero value.
strftime([format])
Formats the date with the given template. The following
conversion specifications are supported:
%A, %a, %B, %b, %C, %c, %D, %d, %e, %F, %G, %g, %H, %h, %I, %j,
%k, %l, %M, %m, %n, %P, %p, %R, %r, %S, %s, %T, %t, %U, %u, %V,
%v, %W, %w, %X, %x, %Y, %y, %Z, %z, %%, %+
See also strftime(3) and strptime.
succ
next
Returns a date object denoting the following day.
to_s
Returns a string in an ISO 8601 format (This method doesn't use
the expanded representations).
upto(max){|date| ...}
This method is equivalent to step(max, 1){|date| ...}.
wday
Returns the day of week (0-6, Sunday is zero).
yday
Returns the day of year (1-366).
year
Returns the year.
DateTime
Super Class
Date
Class Methods
civil([year[, mon[, mday[, hour[, min[, sec[, offset[, start]]]]]]]])
new([year[, mon[, mday[, hour[, min[, sec[, offset[, start]]]]]]]])
Creates a date-time object denoting the given calendar date.
commercial([cwyear[, cweek[, cwday[, hour[, min[, sec[, offset[,
start]]]]]]]])
Creates a date-time object denoting the given week date.
jd([jd[, hour[, min[, sec[, offset[, start]]]]]])
Creates a date-time object denoting the given Julian day
number.
now([start])
Creates a date-time object denoting the present time.
ordinal([year[, yday[, hour[, min[, sec[, offset[, start]]]]]]])
Creates a date-time object denoting the given ordinal date.
Methods
hour
Returns the hour (0-23).
min
Returns the minute (0-59).
new_offset([offset])
Duplicates self and resets the its offset. Default is zero
(UTC).
See also new.
offset
Returns the offset.
sec
Returns the second (0-59).
zone
Returns the timezone.
date/holiday - determination of secular and religious holidays
Date
Class Methods
gregorian_easter(year[, start])
easter(year[, start])
Returns a date object denoting the Easter sunday in the given
Gregorian year.
julian_easter(year[, start])
Returns a date object denoting the Easter sunday in the given
Julian year.
nth_kday(n, k, year, mon[, start])
Returns a date object denoting the given Nth (-5 to 5, except
zero) Kday (0-6) in the given month of year.
Methods
easter?
Returns true if the day is an Easter sunday.
national_holiday?
Returns true if the day is a Japanese national holiday.
nth_kday?(n, k)
Returns true if the day is an Nth (-5 to 5, except zero) Kday
(0-6).
old_national_holiday?
Returns true if the day is an old Japanese national holiday.
This is still experimental.
parsedate - date and time parsing
ParseDate
Module Functions
parsedate(str[, complete])
Parses the given representation of dates and times, and returns
an array which contain detected elements (year, month, day of
month, hour, minute, second, timezone and day of week).
If the optional second argument is true and the detected year
is in the range 0 to 99, considers the year a 2-digit form and
makes it full. Default is false.
See also Date::parse.