From: Robert Gleeson <rob@...>
Date: 2009-12-11T22:49:14+09:00
Subject: Re: Redirecting standard output

> The gem was not needed for the redirection functionality but for
> getting at information about the method.
Yup, I completely missed that! I was tired, and misread the thread 
completely.

>> $stdout = File.new '/path/to/file', 'w'
>> puts 'foobar'
>> $stdout = STDOUT
>> puts 'foobar'
> 
> This does only work for redirections of output for the particular
> process.  It will fail in these cases
> 
> - sub processes started

Hmm really? I thought a fork() would copy the memory from the parent 
process into the subprocess.
Example:

  $stdout = File.open 'foobar.txt', 'w'; fork { $stdout.puts 'Hello' }

  $ cat foobar.txt
    Hello
    => 4301

Am I misunderstanding you?


> - all entities which remembered $stdout instance (e.g. a logger)

I'm not sure I follow you here either.
A reference to $stdout would persist.

  foo = $stdout
  $stdout = File.new 'foobar.txt', 'w'
  # foo still references $stdout

Unless they use #dup, I don't see how the reference to $stdout wouldn't 
persist.

> Your last solution is better (although you do not necessarily need a
> constant for that).

Yup. I just choose a constant to illustrate an example - if $stdout was 
changing often, I'd use something more appropriate.

> Btw, apparently you don't even need the mode -
> that is inherited from the original.  So you can do:
> 
> $ ruby19 -e '$stderr.reopen("log"); $stderr.puts("foo")' ; cat log
> foo
> $ ruby19 -e '$stdin.reopen("log"); p gets'
> "foo\n"
> $

Cool, good to know

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