From: Martin DeMello <martindemello@...>
Date: 2009-12-21T19:37:45+09:00
Subject: Re: redirecting stderr in irb

On Mon, Dec 21, 2009 at 3:39 PM, Ryan Davis <ryand-ruby@zenspider.com> wrote:
>
> On Dec 21, 2009, at 00:26 , Martin DeMello wrote:
>
>> Redirecting $stderr in irb doesn't work but redirecting
>> $DEFAULT_OUTPUT does.
>
> "doesn't work" is hardly true. You're certainly redirecting $stderr at the time. What you're confusing is that $DEFAULT_OUTPUT is not an alias for $stderr, but for $stdout. This is easily testable just by playing with the shell:

Yeah, i know that, but irb seems to be printing its errors to $DEFAULT_OUTPUT

> I think what you really want to do is to temporarily reassign output_method in the context.

Well, irb.rb has

   def output_value
      if @context.inspect?
        printf @context.return_format, @context.last_value.inspect
      else
        printf @context.return_format, @context.last_value
      end
    end

So, if I redefine output_method I also need to reopen Irb to override
output_value and have it call @context.output_method.printf rather
than printf. Anyway I did that, and regular output gets redirected
appropriately, but errors don't. It looks like it's hardcoding
StdioOutputMethod somewhere, but I couldn't figure out how to override
that.

martin