Ruby forgets local variables during a while loop?

Question

I\'m processing a record-based text file: so I\'m looking for a starting string which constitutes the start of a record: there is no end-of-record marker, so I use the start

Answer 1

I'm not sure why you're surprised: on line 5 (assuming that the message = nil line isn't there), you potentially use a variable that the interpreter has never heard of before. The interpreter says "What's message? It's not a method I know, it's not a variable I know, it's not a keyword..." and then you get an error message.

Here's a simpler example to show you what I mean:

while line = gets do
  if line =~ /./ then
    puts message # How could this work?
    message = line
  end
end

Which gives:

telemachus ~ $ ruby test.rb < huh 
test.rb:3:in `
': undefined local variable or method `message' for main:Object (NameError)

Also, if you want to prepare the way for message, I would initialize it as message = '', so that it's a string (rather than nil). Otherwise, if your first line doesn't match hello, you end up tring to add line to nil - which will get you this error:

telemachus ~ $ ruby test.rb < huh 
test.rb:4:in `
': undefined method `<<' for nil:NilClass (NoMethodError)