From: nobu@...
Date: 2015-01-07T09:57:00+00:00
Subject: [ruby-core:67384] [ruby-trunk - Feature #10701] Class:Array 2 New	methods

Issue #10701 has been updated by Nobuyoshi Nakada.

Description updated

An exception should be raised if the input is not found?

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Feature #10701: Class:Array 2 New methods
https://bugs.ruby-lang.org/issues/10701#change-50827

* Author: Eugene Kuhn
* Status: Open
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
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Hi,

New to this, but this is an Array method that I use a lot and thought it might be included in a release, it's basic, but very helpful when you need to rotate certain defined values ie. log rotation with monthly timestamps

~~~ruby
class Array
	def next(value)
		#Returns next element value (and loop to the beginning if last element is matched ) based on first input found. if not found, returns first value of array
		self[((self.index(value)||-1)+1)%self.size]
	end	
	def prev(value)
		#Returns previous element value (and loop to the end if first element is matched ) based on first input found. if not found, returns first value of array
		self[((self.index(value)||1)-1)%self.size]
	end
end


arr1 = ['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec']

puts arr1.next("")    #=> returns "Jan"
puts arr1.prev("")    #=> returns "Jan"
puts arr1.next("Apr") #=> returns "May"
puts arr1.next("Dec") #=> returns "Jan"
puts arr1.prev("Jan") #=> returns "Dec"
puts arr1.prev("Apr") #=> returns "Mar"
~~~



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