块中的可变范围

Question

David A Black(The Well Grounded Rubyist,第6章)提供了以下代码:

def block_local_parameter
  x = 100
  [1,2,3].each do |x|
    puts "Parameter x is #{x}"
    x += 10
    puts "Reassigned to x in block; it is now #{x}"
  end
  puts "The value of outer x is now #{x}"
end

block_local_parameter

按照本书的预期输出(Ruby 1.9.1):

Parameter x is 1
Reassigned to x in block; it's now 11
Parameter x is 2
Reassigned to x in block; it's now 12
Parameter x is 3
Reassigned to x in block; it's now 13
Outer x is still 100

我的输出(Ruby 1.8.7):

Parameter x is 1
Reassigned to x in block; it's now 11
Parameter x is 2
Reassigned to x in block; it's now 12
Parameter x is 3
Reassigned to x in block; it's now 13
Outer x is still 13

这本书错了吗？或者,我错过了什么？

Answer 1

你看到的是Ruby 1.8.x的行为.块的可变范围在1.9中引入,切换到1.9.x,您将获得与书中相同的结果.