From: tadayoshi funaba <redmine@...>
Date: 2011-06-09T19:18:22+09:00
Subject: [ruby-core:36881] [Ruby 1.9 - Bug #4460] Date.commercial date calculations don't match strftime output


Issue #4460 has been updated by tadayoshi funaba.


repost code

=begin
 > Date.new(2011,2,28).strftime('%G-%V-%u') 
 #=> "2011-09-1"
 > Date.new(2011,2,28).next_year(2).strftime('%G-%V-%u') 
 #=> "2013-09-4"
 
 > Date.commercial(2011,9,1)
 #=> #<Date: 2011-02-28 ((2455621j,0s,0n),+0s,2299161j)>
 > Date.commercial(2013,9,4)
 #=> #<Date: 2013-02-28 ((2456352j,0s,0n),+0s,2299161j)>
 
 > Date.strptime('2011-09-1', '%G-%V-%u')
 #=> #<Date: 2011-02-28 ((2455621j,0s,0n),+0s,2299161j)>
 
 > Date.strptime('2013-09-4', '%G-%V-%u')
 #=> #<Date: 2013-02-28 ((2456352j,0s,0n),+0s,2299161j)>

=end

----------------------------------------
Bug #4460: Date.commercial date calculations don't match strftime output
http://redmine.ruby-lang.org/issues/4460

Author: Jaap Haagmans
Status: Rejected
Priority: Normal
Assignee: tadayoshi funaba
Category: 
Target version: 
ruby -v: ruby 1.9.2p180 (2011-02-18 revision 30909) [x86_64-linux]


=begin
When retrieving the date for a week number using Date.commercial, the output sometimes differs from what you expect when looking at strftime. In my opinion, the following should always be true:

(({Date.commercial(year, week, day).strftime('%W') => week (String) }))

Which is in fact true today:

(({Date.today.strftime('%W') => "09"
Date.commercial(2011,9,1) => Mon, 28 Feb 2011
Date.today.at_beginning_of_week => Mon, 28 Feb 2011 }))

But not two years from now:

(({(Date.today+2.years).strftime("%W") => "08"
Date.commercial(2013,8,1) => Mon, 18 Feb 2013
(Date.today+2.years).at_beginning_of_week => Mon, 25 Feb 2013 }))

so:

(({Date.commercial(2013,8,1).strftime('%W') => "7"}))

I'm not quite sure why this is, but I think it's a bug and unfortunately it messes up some of my date calculations.
=end



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