Ruby在while循环期间会忘记局部变量？

所以我已经建立了一个简单的程序来做到这一点,但是我看到一些令我震惊的东西：看起来Ruby正在忘记局部变量存在 – 或者我发现编程错误？ [虽然我不认为我有：如果我在我的循环之前定义变量’message’,我看不到错误].

这是一个简化的示例,其中包含注释中的输入数据和错误消息：

flag=false
# message=nil # this is will prevent the issue.
while line=gets do
    if line =~/hello/ then
        if flag==true then
            puts "#{message}"
        end
        message=StringIO.new(line);
        puts message
        flag=true
    else
        message << line
    end
end

# Input File example:
# hello this is a record
# this is also part of the same record
# hello this is a new record
# this is still record 2
# hello this is record 3 etc etc
# 
# Error when running: [nb,first iteration is fine]
# <StringIO:0x2e845ac>
# hello
# test.rb:5: undefined local variable or method `message' for main:Object (NameError)
#