تضمين Enumerable

الحصول على map وselect مجانًا

class Bag
  include Enumerable
  def initialize(*x); @x = x; end
  def each; @x.each { |i| yield i }; end
end
p Bag.new(1, 2, 3).map { |n| n * 10 }

العقد

class Squares
  include Enumerable
  def initialize(n); @n = n; end
  def each
    (1..@n).each { |i| yield i * i }
  end
end
p Squares.new(5).to_a

التصفية باستخدام select

class Nums
  include Enumerable
  def initialize(*x); @x = x; end
  def each; @x.each { |i| yield i }; end
end
n = Nums.new(1, 2, 3, 4, 5, 6)
p n.select(&:even?)
p n.reject(&:even?)

التجميع باستخدام reduce

class Cart
  include Enumerable
  def initialize(*p); @p = p; end
  def each; @p.each { |i| yield i }; end
end
puts Cart.new(5, 10, 15).reduce(:+)

min وmax وsort

class Scores
  include Enumerable
  def initialize(*n); @n = n; end
  def each; @n.each { |i| yield i }; end
end
s = Scores.new(7, 2, 9, 4)
puts s.min
puts s.max
p s.sort

find وinclude?

class Words
  include Enumerable
  def initialize(*w); @w = w; end
  def each; @w.each { |x| yield x }; end
end
w = Words.new("cat", "dog", "bird")
puts w.find { |x| x.length == 4 }
puts w.include?("dog")

group_by وpartition

class Nums
  include Enumerable
  def initialize(*x); @x = x; end
  def each; @x.each { |i| yield i }; end
end
n = Nums.new(1, 2, 3, 4, 5)
p n.group_by(&:even?)
p n.partition(&:odd?)

يتطلب الفرز عناصر قابلة للمقارنة

Item = Struct.new(:price) do
  include Comparable
  def <=>(o); price <=> o.price; end
end
class Shelf
  include Enumerable
  def initialize(*i); @i = i; end
  def each; @i.each { |x| yield x }; end
end
shelf = Shelf.new(Item.new(30), Item.new(10), Item.new(20))
p shelf.min.price

each_with_index

class Letters
  include Enumerable
  def initialize(*l); @l = l; end
  def each; @l.each { |x| yield x }; end
end
Letters.new("a", "b", "c").each_with_index do |letter, i|
  puts "#{i}: #{letter}"
end

ربط الأساليب

class Nums
  include Enumerable
  def initialize(*x); @x = x; end
  def each; @x.each { |i| yield i }; end
end
result = Nums.new(1, 2, 3, 4, 5, 6).select(&:even?).map { |n| n * n }
p result

تجميع المفاهيم

class Range5
  include Enumerable
  def each; (1..5).each { |n| yield n }; end
end
puts Range5.new.sum

اختبار سريع

مراجعة

class Tens
  include Enumerable
  def each; [10, 20, 30].each { |n| yield n }; end
end
p Tens.new.map { |n| n + 1 }