From: Massimiliano Mirra <list@...>
Date: 2002-07-09T00:14:33+09:00
Subject: Re: Redirecting standard error

On Mon, Jul 08, 2002 at 10:04:04PM +0900, Gilles Filippini wrote:
> I saw many examples about how to redirect standard output to - say - a
> string buffer.
> What about standard error? Has anybody already done this?

I wrote and currently use a StringIO.  You can do something like this:

out, err = StringIO.new, StringIO.new

redir(out, err) do
  puts "hello, world!"
  $stderr.puts "ooops!"
end

p out.to_s  >>  "hello, world!\n"
p err.to_s  >>  "ooops!\n"


I use it mostly for writing test cases of things that would otherwise
hold conversation with the user.  Just assign a StringIO to $stdin, in
fact, and you can simulate user input as well.

It's far from perfect, biggest deficiency being that it always works
in `w+' (read/write) mode, so it doesn't prevent from doing stupid
things.  It will become unnecessary when Ruby 1.8 will be out as it
contains a StringIO of its own.

If you want to have a look at it, I'll put it online at
http://www.allruby.com/rpkg/stringio.rb by tonight.


Massimiliano