From: Josh Cheek <josh.cheek@...>
Date: 2010-08-03T06:40:53+09:00
Subject: Re: .any?{} Behavior

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What about redefining all? to accept an optional param for what to do when
empty? It doesn't change default behaviour, but lets you get your preferred
behaviour out of it. (note this only works on 1.9, because of how procs take
params in 1.8)


module Enumerable
  old_all = instance_method(:all?)
  define_method :all? do |emptyval=true,&block|
    return emptyval if empty?
    old_all.bind(self).call &block
  end
end

require 'test/unit'

class NewAllTest < Test::Unit::TestCase
  def test_empty
    assert ![].all?(false)
    assert  [].all?(true)
    assert  [].all?
  end
  def test_non_empty_no_block
    assert ![ nil, true, 99 ].all?(true)
    assert ![ nil, true, 99 ].all?(false)
    assert ![ nil, true, 99 ].all?
    assert  [  '', true, 99 ].all?(true)
    assert  [  '', true, 99 ].all?(false)
    assert  [  '', true, 99 ].all?
  end
  def test_non_empty_block
    assert  [ 1, 3, 99 ].all?( true    , &:odd? )
    assert  [ 1, 3, 99 ].all?( false   , &:odd? )
    assert  [ 1, 3, 99 ].all?(           &:odd? )
    assert ![ 1, 2, 99 ].all?( true    , &:odd? )
    assert ![ 1, 2, 99 ].all?( false   , &:odd? )
    assert ![ 1, 2, 99 ].all?(           &:odd? )
  end
  def test_non_array
    assert Hash[*1..10].all? { |key,value| key.odd? && value.even? }
  end
end

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