From: WATANABE Hirofumi <eban@...>
Date: 2002-11-15T12:48:56+09:00
Subject: Re: Howot redirect STDOUT to a string within a script?

Phil Tomson <ptkwt@shell1.aracnet.com> writes:

> Let's say I've got some strings with Ruby code to be eval'ed, like:
> 
> evalstr = 'puts "this is the string"'
> 
> and let's say I want to get the part that's sent to STDOUT (by puts) and 
> capture it in a string, like so:
> 
> outputStr = eval evalstr #=> outputStr = "this is the string"
> 
> I suspect I could do this by redefining 'puts', but is there a way of 
> doing it so that puts is only redefined within the context of the eval?

Ruby 1.7 has StringIO.

require 'stringio'

def redirect
  orig_defout = $defout
  $defout = StringIO.new
  yield
  $defout.string
ensure
  $defout = orig_defout
end

evalstr = 'puts "this is the string"'
outputStr = redirect { eval evalstr }
p outputStr

If you want to use StringIO in Ruby 1.6, check Ruby Shim:
  http://www.ruby-lang.org/en/raa-list.rhtml?name=Ruby+Shim+for+1.6
or MoonWolf's StringIO:
  //http://www.moonwolf.com/ruby/archive/stringio01.zip

-- 
eban