Class Date
In: lib/vpim/date.rb
Parent: Object

Extensions to the standard library Date.

Methods

bywday   str2wday   vpim_to_time   weekstart  

Constants

TIME_START = Date.new(1970, 1, 1)
SECS_PER_DAY = 24 * 60 * 60

Public Class methods

bywday(year, mon, wday, n = 1, sg=Date::ITALY)

Create a new Date object for the date specified by year year, month mon, and day-of-the-week wday.

The nth, n, occurrence of wday within the period will be generated (n defaults to 1). If n is positive, the nth occurrence from the beginning of the period will be returned, if negative, the nth occurrence from the end of the period will be returned.

The period is a year, unless month is non-nil, in which case it is just that month.

Examples:

  • Date.bywday(2004, nil, 1, 9) => the ninth Sunday of 2004
  • Date.bywday(2004, nil, 1) => the first Sunday of 2004
  • Date.bywday(2004, nil, 1, -2) => the second last Sunday of 2004
  • Date.bywday(2004, 12, 1) => the first sunday in the 12th month of 2004
  • Date.bywday(2004, 2, 2, -1) => last Tuesday in the 2nd month in 2004
  • Date.bywday(2004, -2, 3, -2) => second last Wednesday in the second last month of 2004

Compare this to Date.new, which allows a Date to be created by day-of-the-month, mday, to Date.ordinal, which allows a Date to be created by day-of-the-year, yday, and to Date.commercial, which allows a Date to be created by day-of-the-week, but within a specific week.

str2wday(wdaystr)

If wday responds to to_str, convert it to the wday number by searching for a wday that matches, using as many characters as are in wday to do the comparison. wday must be 2 or more characters long in order to be a unique match, other than that, "mo", "Mon", and "MonDay" are all valid strings for wday 1.

This method can be called on a valid wday, and it will return it. Perhaps it should be called by default inside the Date#new*() methods so that non-integer wday arguments can be used? Perhaps a similar method should exist for months? But with months, we all know January is 1, who can remember where Date chooses to start its wday count!

Examples: 

 Date.bywday(2004, 2, Date.str2wday('TU')) => the first Tuesday in
   February
 Date.bywday(2004, 2, Date.str2wday(2)) => the same day, but notice
   that a valid wday integer can be passed right through.
weekstart(year, mon, day, weekstart="MO")

Return the first day of the week for the specified date. Commercial weeks start on Monday, but the weekstart can be specified (as 0-6, where 0 is sunday, or in formate of Date.str2day).

Public Instance methods

vpim_to_time()

Converts this object to a Time object, or throws an ArgumentError if conversion is not possible because it is before the start of epoch.

[Validate]