eval_api_类中类_map

（一）eval("a=1;b=2;puts a+b")
运行结果
vagrant@vagrant-Ubuntu-trusty-64:/vagrant/test_PRoject$ ruby Apple4.rb
3
（二）查看api
Reference Documentation就是API


（三）类中类及类中类之方法
class Fruit
  COLOR='red'
  class Apple
    COLOR='red'
    def size
      puts 'big'
    end
  end
end
puts Fruit::Apple::COLOR
puts Fruit::Apple.new.size运行结果
vagrant@vagrant-ubuntu-trusty-64:/vagrant/test_project$ ruby Apple4.rb
red
big
（四）map用法
result=[1,2,3].map do |e|
  e*e
end
puts result.inspect