函数对象作为case语句中的条件

Ruby 1.9的Proc#===作为call的一个别名，所以函数对象可以作为case语句中的条件

def multiple_of(factor)
    lambda{|num| num % factor == 0}
end
#or
#def multiple_of(factor)
#    proc{|num| num % factor == 0}
#end
#
while number = gets.to_i
    case number
        when multiple_of(2)
            puts "multiple of 2"
        when multiple_of(3)
            puts "multiple of 3"
        when multiple_of(5)
            puts "multiple of 5"
        else
            puts "#{number} is not multiple of 2,3,5" 
    end
end