Iterate every month with date objects

Question

So I have two ruby Date objects, and I want to iterate them every month. For example if I have Date.new(2008, 12) and Date.new(2009, 3), it would yield me 2008-12, 2009-1, 2009-

Answer 1

I came up with the following solution. It's a mixin for date ranges that adds an iterator for both years and months. It yields sub-ranges of the complete range.

    require 'date'

    module EnumDateRange  
      def each_year
        years = []
        if block_given?    
          grouped_dates = self.group_by {|date| date.year}
          grouped_dates.each_value do |dates|
            years << (yield (dates[0]..dates[-1]))
          end
        else
          return self.enum_for(:each_year)
        end
        years
      end

      def each_month
        months = []
        if block_given?
          self.each_year do |range|
            grouped_dates = range.group_by {|date| date.month}
            grouped_dates.each_value do |dates|
              months << (yield (dates[0]..dates[-1]))
            end
          end
        else
          return self.enum_for(:each_month)
        end
        months
      end  
    end

    first = Date.parse('2009-01-01')
    last = Date.parse('2011-01-01')

    complete_range = first...last
    complete_range.extend EnumDateRange

    complete_range.each_year {|year_range| puts "Year: #{year_range}"}
    complete_range.each_month {|month_range| puts "Month: #{month_range}"}

Will give you:

Year: 2009-01-01..2009-12-31
Year: 2010-01-01..2010-12-31
Month: 2009-01-01..2009-01-31
Month: 2009-02-01..2009-02-28
Month: 2009-03-01..2009-03-31
Month: 2009-04-01..2009-04-30
Month: 2009-05-01..2009-05-31
Month: 2009-06-01..2009-06-30
Month: 2009-07-01..2009-07-31
Month: 2009-08-01..2009-08-31
Month: 2009-09-01..2009-09-30
Month: 2009-10-01..2009-10-31
Month: 2009-11-01..2009-11-30
Month: 2009-12-01..2009-12-31
Month: 2010-01-01..2010-01-31
Month: 2010-02-01..2010-02-28
Month: 2010-03-01..2010-03-31
Month: 2010-04-01..2010-04-30
Month: 2010-05-01..2010-05-31
Month: 2010-06-01..2010-06-30
Month: 2010-07-01..2010-07-31
Month: 2010-08-01..2010-08-31
Month: 2010-09-01..2010-09-30
Month: 2010-10-01..2010-10-31
Month: 2010-11-01..2010-11-30
Month: 2010-12-01..2010-12-31