to_proc

to_proc.rb

class Filter
  def initialize()
    @constraints = []
  end

  def constraint(&block)
    @constraints << block
  end

  def to_proc
    lambda { |e| @constraints.all? {|fn| fn.call(e) }}
  end
end

if __FILE__ == $0
  filter = Filter.new
  filter.constraint {|x| x > 10 }
  filter.constraint {|x| x.even? }

  p (8..34).select(&filter)
  p (8..34).select(&filter.to_proc)


  puts ['a','b','c'].map(&:upcase)

  class Symbol
    def to_proc
       lambda { |e| puts "You want me to do #{self}. hahaha no way" }
    end
  end

  puts ['a','b','c'].map(&:upcase)

end

~