Can you temporarily turn off STDERR?

Awesome. Now, can we break this with threads? Aredridel?

Of course, I wonder if IO#reopen is thread safe anyway, regardless of
the block. I've never seriously tested it.

Regards,

Dan

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-----Original Message-----
From: Stephen Veit [mailto:srveit@gmail.com]
Sent: Friday, August 25, 2006 3:32 PM
To: ruby-talk ML
Subject: Re: Can you temporarily turn off STDERR ??

On 8/25/06, Berger, Daniel <Daniel.Berger@qwest.com> wrote:
>
> This comes up often enough that I wonder if allowing
IO#reopen to take
> a block would be a good idea:
>
> $stderr.reopen('/dev/null') do
> # Code here redirects to /dev/null
> end
>
> # Code outside the block behaves normally
>
> I thought this idea had been brought up before, and that there was
> some downside to this, but I can't find any references to it now.
>
> Thoughts?
>
> - Dan

How about this?

#!/usr/bin/env ruby

# reopen_with_block.rb

class IO

  alias_method :_orig_reopen, :reopen

  def reopen(*args)
    if block_given?
      is_path = args.length == 2
      path_or_io, mode_str = args
      old_io = clone
      path_or_io = File.open(path_or_io, mode_str || "w") if is_path
      _orig_reopen(path_or_io)
      begin
        yield
      ensure
        _orig_reopen(old_io)
        path_or_io.close if is_path
      end
    else
      _orig_reopen(*args)
    end
  end

end

if $0 == __FILE__
  $stderr.reopen('error_log', 'w') do
    $stderr.puts "Stuff on error"
    puts "normal stuff"
  end

  File.open('error_log_2', "w") do |file|
    $stderr.reopen(file) do
      $stderr.puts "Stuff on error 2"
      puts "normal stuff 2"
    end
  end

  $stderr.reopen('/dev/null') do
    $stderr.puts "Stuff on error 3"
    puts "normal stuff 3"
  end

  # Make sure old way works
  old_stderr = $stderr.clone
  File.open('error_log_4', 'w') do |log_file|
    $stderr.reopen(log_file)
    begin
      $stderr.puts "Stuff on error 4"
      puts "normal stuff 4"
    ensure
      $stderr.reopen(old_stderr)
    end
  end

  begin
    $stderr.reopen('error_log_5', 'w') do
      $stderr.puts "Stuff on error 5"
      puts "normal stuff 5"
      raise "This message courtesy of raise"
    end
  rescue => e
    puts e
  end

end

Awesome. Now, can we break this with threads? Aredridel?

Of course, I wonder if IO#reopen is thread safe anyway, regardless of
the block. I've never seriously tested it.

Well, it's thread-safe, but it's process-global. It'd get turned off for
the duration of the block, regardless of other threads.