Ruby的一些疑问
1、网点看到一断程序，

class Filter  def initialize    @constraints = []  end  def constraint(&block)    @constraints << block  end  def to_proc    lambda { |e| @constraints.all? { |fn| fn.call(e) } }  endendfilter = Filter.newfilter.constraint { |x| x > 10 }filter.constraint { |x| x.even? }filter.constraint { |x| x % 3 == 0 }p (8..24).select(&filter) #=> [12,18,24]