From: "DanDiebolt.exe" <dandiebolt@...>
Date: 2008-09-11T02:53:12+09:00
Subject: Redefe each to include each_with_index and arity=2

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Is is possible to redefine each so that each_with_index behavior can be ach=
eived with an extra parameter to the block each is called with? In other wo=
rds, how do you redefine each so that instead of using this construct:
=A0
=A0 a.each_with_index do |item,index|
=A0
=A0 end
=A0
you can use this one:
=A0
=A0 a.each do |item,index|
=A0
=A0 end
=A0
as well not disturbing this usage:
=A0
=A0 a.each do |item|
=A0
=A0 end
=A0
=3D=3D=3D=3D=3D=3D
This is my attempt to redefine Array#each but it does not work:
=A0
class Array
=A0 alias :old_each :each
=A0 def each(&block)
=A0=A0=A0 puts "arity=3D#{block.arity}"
=A0=A0=A0 case block.arity
=A0=A0=A0 when 1=20
=A0=A0=A0=A0=A0 old_each &block
=A0=A0=A0 when 2
=A0=A0=A0=A0=A0 each_with_index &block
=A0=A0=A0 end
=A0 end
end
=A0
a=3D[1,2,3]
=A0
irb(main):030:0> a.each do |item|
irb(main):031:1*=A0 puts "item=3D#{item}"
irb(main):032:1> end
arity=3D1
item=3D1
item=3D2
item=3D3
=3D> [1, 2, 3]
=A0
irb(main):033:0> a.each do |item,index|
irb(main):034:1*=A0 puts "item=3D#{item}, index=3D#{index}"
irb(main):035:1> end
arity=3D2
arity=3D-1
=3D> [1, 2, 3]
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