ruby学习--block

#当前块
class Block
    def a_method
        return yield if block_given?
        'no block'
    end
end
obj=Block.new
puts "#{obj.a_method}"
puts "#{obj.a_method {"here's a block!"}}"

#闭包
class Greeter
    def initialize(name)
        @name=name
    end
    def name
        @name
    end
    def name=(new_name)
        @name=new_name
    end
end
g=Greeter.new("Barney")
puts g.name 　　　　
g.name="Betty"
puts g.name　　　　　　 

#切换作用域
v1=1
class MyClass
    v2=2
    local_variables                    
    #puts "#{local_variables}"　　     #[:v2]　　
    def my_method
        v3=3
        local_variables
        #puts "#{local_variables}"    #[:v3]
    end
    local_variables
    #puts "#{local_variables}"        #[:v2]

end
obj=MyClass.new
obj.my_method                        #[:v3]
puts "#{local_variables}"            #[:v1, :obj]