Is there an easy way to capture standard out in Ruby, so that "puts"
throws its output into a buffer instead of just popping up on the
screen?
I have a scriopt producing output for bash, for running the test spec
I plugin output into an array, more or less like this:
class Output
@data =
class << self
attr_reader :data
end
end
if $TESTING then
def Kernl.puts *args, &blk
Output.data << args.join("")
Output.data << blk.call if blk
end
end
I have also Output.data.clear in #setup of the testsuite.
HTH
Robert
···
On 3/19/07, Giles Bowkett <gilesb@gmail.com> wrote:
Is there an easy way to capture standard out in Ruby, so that "puts"
throws its output into a buffer instead of just popping up on the
screen?--
Giles Bowkett
http://www.gilesgoatboy.org
http://gilesbowkett.blogspot.com
http://giles.tumblr.com/
--
You see things; and you say Why?
But I dream things that never were; and I say Why not?
-- George Bernard Shaw
This is exactly the problem shell IO redirection was designed to solve.
$ ruby script.rb > output
What is the use case that prevents you from using shell redirection?
Gary Wright
···
On Mar 19, 2007, at 6:18 PM, Giles Bowkett wrote:
Is there an easy way to capture standard out in Ruby, so that "puts"
throws its output into a buffer instead of just popping up on the
screen?
You can set the $stdout global variable to point to whatever object you
like, as long as it adheres to a simple interface. Kernel#puts simply
redirects to $stdout.
Cheers,
Daniel
···
On Tue, 2007-03-20 at 07:18 +0900, Giles Bowkett wrote:
Is there an easy way to capture standard out in Ruby, so that "puts"
throws its output into a buffer instead of just popping up on the
screen?
I would do it like this:
#!/usr/bin/env ruby -w
require "stringio"
def capture_stdout(buffer = StringIO.new)
saved_stdout = $stdout
$stdout = buffer
yield
$stdout = saved_stdout
buffer.string rescue buffer
end
if __FILE__ == $PROGRAM_NAME
puts "This will be printed."
output = capture_stdout { puts "Meanwhile, this was captured." }
puts "This also will be printed."
p output
end
__END__
James Edward Gray II
···
On Mar 19, 2007, at 5:18 PM, Giles Bowkett wrote:
Is there an easy way to capture standard out in Ruby, so that "puts"
throws its output into a buffer instead of just popping up on the
screen?
> Is there an easy way to capture standard out in Ruby, so that "puts"
> throws its output into a buffer instead of just popping up on the
> screen?You can set the $stdout global variable to point to whatever object you
like, as long as it adheres to a simple interface. Kernel#puts simply
redirects to $stdout.
That is a good idea too, especially with this idiom
def xxx(..., out = $stdout)
Robert
···
On 3/19/07, Daniel Schierbeck <daniel.schierbeck@gmail.com> wrote:
On Tue, 2007-03-20 at 07:18 +0900, Giles Bowkett wrote:
Cheers,
Daniel
--
You see things; and you say Why?
But I dream things that never were; and I say Why not?
-- George Bernard Shaw
Hey Daniel, I found an example of the $stdout technique from Matz:
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/15519
That's what I ended up using, although I used $stdout and instead of
$defout, and the documentation I found said assigning to $stdout is
deprecated in favor of $stdout.reopen, which I couldn't seem to get to
work for me.
···
On 3/19/07, Daniel Schierbeck <daniel.schierbeck@gmail.com> wrote:
On Tue, 2007-03-20 at 07:18 +0900, Giles Bowkett wrote:
> Is there an easy way to capture standard out in Ruby, so that "puts"
> throws its output into a buffer instead of just popping up on the
> screen?You can set the $stdout global variable to point to whatever object you
like, as long as it adheres to a simple interface. Kernel#puts simply
redirects to $stdout.Cheers,
Daniel
--
Giles Bowkett
http://www.gilesgoatboy.org
I have no idea, I'm solving this for somebody I work with, but I'm
pretty confident they're familiar with shell redirection already.
Thanks tho.
···
On 3/19/07, Gary Wright <gwtmp01@mac.com> wrote:
What is the use case that prevents you from using shell redirection?
--
Giles Bowkett
http://www.gilesgoatboy.org
Here's a code snippet from my log library.
gegroet,
Erik V. - http://www.erikveen.dds.nl/
···
----------------------------------------------------------------
["$stdout", "$stderr"].each do |std|
io = eval(std)
old_write = io.method(:write)
class << io
self
end.module_eval do
define_method(:write) do |text|
unless text =~ /^[\r\n]+$/ # Because puts calls twice.
File.open("logfile.log", "a") do |f|
f.puts [std[1..-1].upcase, caller[2], text].join(" ")
end
end
old_write.call(text)
end
end
end
$stdout.puts "text on stdout"
$stderr.puts "text on stderr"
----------------------------------------------------------------