块中的变量范围

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

根据本书的预期输出（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

您看到的是 Ruby 1.8.x 的行为。块的可变作用域是在 1.9 中引入的，切换到 1.9.x，你会得到与书中相同的结果。