123456789_123456789_123456789_123456789_123456789_

Module: Bundler::Thor::Actions

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Class Method Details

.included(base)

This method is for internal use only.
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 14

def self.included(base) #:nodoc:
  base.extend ClassMethods
end

Instance Attribute Details

#behavior (rw)

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 12

attr_accessor :behavior

#destination_root (rw)

Returns the root for this thor class (also aliased as destination root).

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 100

def destination_root
  @destination_stack.last
end

#destination_root=(root) (rw)

Sets the root for this thor class. Relatives path are added to the directory where the script was invoked and expanded.

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 107

def destination_root=(root)
  @destination_stack ||= []
  @destination_stack[0] = File.expand_path(root || "")
end

#output_buffer (rw, private)

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 330

attr_accessor :output_buffer

Instance Method Details

#_cleanup_options_and_set(options, key) (protected)

This method is for internal use only.
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 310

def _cleanup_options_and_set(options, key) #:nodoc:
  case options
  when Array
    %w(--force -f --skip -s).each { |i| options.delete(i) }
    options << "--#{key}"
  when Hash
    [:force, :skip, "force", "skip"].each { |i| options.delete(i) }
    options.merge!(key => true)
  end
end

#_shared_configuration (protected)

This method is for internal use only.

Allow current root to be shared between invocations.

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 306

def _shared_configuration #:nodoc:
  super.merge!(:destination_root => destination_root)
end

#action(instance)

This method is for internal use only.

Wraps an action object and call it accordingly to the thor class behavior.

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 90

def action(instance) #:nodoc:
  if behavior == :revoke
    instance.revoke!
  else
    instance.invoke!
  end
end

#add_file(destination, *args, &block)

Alias for #create_file.

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/create_file.rb', line 27

alias_method :add_file, :create_file

#append_file(path, *args, &block)

Alias for #append_to_file.

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 191

alias_method :append_file, :append_to_file

#append_to_file(path, *args, &block) Also known as: #append_file

Append text to a file. Since it depends on insert_into_file, it’s reversible.

Parameters

path<String>

path of the file to be changed

data<String>

the data to append to the file, can be also given as a block.

config<Hash>

give :verbose => false to not log the status.

Example

append_to_file 'config/environments/test.rb', 'config.gem "rspec"'

append_to_file 'config/environments/test.rb' do
  'config.gem "rspec"'
end
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 186

def append_to_file(path, *args, &block)
  config = args.last.is_a?(Hash) ? args.pop : {}
  config[:before] = /\z/
  insert_into_file(path, *(args << config), &block)
end

#apply(path, config = {})

Loads an external file and execute it in the instance binding.

Parameters

path<String>

The path to the file to execute. Can be a web address or a relative path from the source root.

Examples

apply "http://gist.github.com/103208"

apply "recipes/jquery.rb"
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 211

def apply(path, config = {})
  verbose = config.fetch(:verbose, true)
  is_uri  = path =~ %r{^https?\://}
  path    = find_in_source_paths(path) unless is_uri

  say_status :apply, path, verbose
  shell.padding += 1 if verbose

  contents = if is_uri
    open(path, "Accept" => "application/x-thor-template", &:read)
  else
    open(path, &:read)
  end

  instance_eval(contents, path)
  shell.padding -= 1 if verbose
end

#capture(*args) (private)

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 339

def capture(*args)
  with_output_buffer { yield(*args) }
end

#chmod(path, mode, config = {})

Changes the mode of the given file or directory.

Parameters

mode<Integer>

the file mode

path<String>

the name of the file to change mode

config<Hash>

give :verbose => false to not log the status.

Example

chmod "script/server", 0755
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 139

def chmod(path, mode, config = {})
  return unless behavior == :invoke
  path = File.expand_path(path, destination_root)
  say_status :chmod, relative_to_original_destination_root(path), config.fetch(:verbose, true)
  unless options[:pretend]
    require "fileutils"
    FileUtils.chmod_R(mode, path)
  end
end

#comment_lines(path, flag, *args)

Comment all lines matching a given regex. It will leave the space which existed before the beginning of the line in tact and will insert a single space after the comment hash.

Parameters

path<String>

path of the file to be changed

flag<Regexp|String>

the regexp or string used to decide which lines to comment

config<Hash>

give :verbose => false to not log the status.

Example

comment_lines 'config/initializers/session_store.rb', /cookie_store/
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 301

def comment_lines(path, flag, *args)
  flag = flag.respond_to?(:source) ? flag.source : flag

  gsub_file(path, /^(\s*)([^#|\n]*#{flag})/, '\1# \2', *args)
end

#concat(string) (private)

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 335

def concat(string)
  @output_buffer.concat(string)
end

#copy_file(source, *args, &block)

Examples

copy_file "README", "doc/README"

copy_file "doc/README"
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 21

def copy_file(source, *args, &block)
  config = args.last.is_a?(Hash) ? args.pop : {}
  destination = args.first || source
  source = File.expand_path(find_in_source_paths(source.to_s))

  create_file destination, nil, config do
    content = File.binread(source)
    content = yield(content) if block
    content
  end
  if config[:mode] == :preserve
    mode = File.stat(source).mode
    chmod(destination, mode, config)
  end
end

#create_file(destination, *args, &block) Also known as: #add_file

Create a new file relative to the destination root with the given data, which is the return value of a block or a data string.

Parameters

destination<String>

the relative path to the destination root.

data<String|NilClass>

the data to append to the file.

config<Hash>

give :verbose => false to not log the status.

Examples

create_file "lib/fun_party.rb" do
  hostname = ask("What is the virtual hostname I should use?")
  "vhost.name = #{hostname}"
end

create_file "config/apache.conf", "your apache config"
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/create_file.rb', line 22

def create_file(destination, *args, &block)
  config = args.last.is_a?(Hash) ? args.pop : {}
  data = args.first
  action CreateFile.new(self, destination, block || data.to_s, config)
end

#directory(source, *args, &block)

Copies recursively the files from source directory to root directory. If any of the files finishes with .tt, it’s considered to be a template and is placed in the destination without the extension .tt. If any empty directory is found, it’s copied and all #empty_directory files are ignored. If any file name is wrapped within % signs, the text within the % signs will be executed as a method and replaced with the returned value. Let’s suppose a doc directory with the following files:

doc/
  components/.empty_directory
  README
  rdoc.rb.tt
  %app_name%.rb

When invoked as:

directory "doc"

It will create a doc directory in the destination with the following files (assuming that the app_name method returns the value “blog”):

doc/
  components/
  README
  rdoc.rb
  blog.rb

Encoded path note: Since ::Bundler::Thor internals use Object#respond_to? to check if it can expand %something%, this something should be a public method in the class calling #directory. If a method is private, ::Bundler::Thor stack raises PrivateMethodEncodedError.

Parameters

source<String>

the relative path to the source root.

destination<String>

the relative path to the destination root.

config<Hash>

give :verbose => false to not log the status. If :recursive => false, does not look for paths recursively. If :mode => :preserve, preserve the file mode from the source. If :exclude_pattern => /regexp/, prevents copying files that match that regexp.

Examples

directory "doc"
directory "doc", "docs", :recursive => false
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/directory.rb', line 49

def directory(source, *args, &block)
  config = args.last.is_a?(Hash) ? args.pop : {}
  destination = args.first || source
  action Directory.new(self, source, destination || source, config, &block)
end

#empty_directory(destination, config = {})

Creates an empty directory.

Parameters

destination<String>

the relative path to the destination root.

config<Hash>

give :verbose => false to not log the status.

Examples

empty_directory "doc"
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/empty_directory.rb', line 13

def empty_directory(destination, config = {})
  action EmptyDirectory.new(self, destination, config)
end

#find_in_source_paths(file)

Receives a file or directory and search for it in the source paths.

Raises:

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 132

def find_in_source_paths(file)
  possible_files = [file, file + TEMPLATE_EXTNAME]
  relative_root = relative_to_original_destination_root(destination_root, false)

  source_paths.each do |source|
    possible_files.each do |f|
      source_file = File.expand_path(f, File.join(source, relative_root))
      return source_file if File.exist?(source_file)
    end
  end

  message = "Could not find #{file.inspect} in any of your source paths. ".dup

  unless self.class.source_root
    message << "Please invoke #{self.class.name}.source_root(PATH) with the PATH containing your templates. "
  end

  message << if source_paths.empty?
               "Currently you have no source paths."
             else
               "Your current source paths are: \n#{source_paths.join("\n")}"
             end

  raise Error, message
end

#get(source, *args, &block)

Gets the content at the given address and places it at the given relative destination. If a block is given instead of destination, the content of the url is yielded and used as location.

Parameters

source<String>

the address of the given content.

destination<String>

the relative path to the destination root.

config<Hash>

give :verbose => false to not log the status.

Examples

get "http://gist.github.com/103208", "doc/README"

get "http://gist.github.com/103208" do |content|
  content.split("\n").first
end
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 76

def get(source, *args, &block)
  config = args.last.is_a?(Hash) ? args.pop : {}
  destination = args.first

  if source =~ %r{^https?\://}
    require "open-uri"
  else
    source = File.expand_path(find_in_source_paths(source.to_s))
  end

  render = open(source) { |input| input.binmode.read }

  destination ||= if block_given?
    block.arity == 1 ? yield(render) : yield
  else
    File.basename(source)
  end

  create_file destination, render, config
end

#gsub_file(path, flag, *args, &block)

Run a regular expression replacement on a file.

Parameters

path<String>

path of the file to be changed

flag<Regexp|String>

the regexp or string to be replaced

replacement<String>

the replacement, can be also given as a block

config<Hash>

give :verbose => false to not log the status.

Example

gsub_file 'app/controllers/application_controller.rb', /#\s*(filter_parameter_logging :password)/, '\1'

gsub_file 'README', /rake/, :green do |match|
  match << " no more. Use thor!"
end
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 255

def gsub_file(path, flag, *args, &block)
  return unless behavior == :invoke
  config = args.last.is_a?(Hash) ? args.pop : {}

  path = File.expand_path(path, destination_root)
  say_status :gsub, relative_to_original_destination_root(path), config.fetch(:verbose, true)

  unless options[:pretend]
    content = File.binread(path)
    content.gsub!(flag, *args, &block)
    File.open(path, "wb") { |file| file.write(content) }
  end
end

#in_root

Goes to the root and execute the given block.

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 195

def in_root
  inside(@destination_stack.first) { yield }
end

#initialize(args = [], options = {}, config = {})

Extends initializer to add more configuration options.

Configuration

behavior<Symbol>

The actions default behavior. Can be :invoke or :revoke. It also accepts :force, :skip and :pretend to set the behavior and the respective option.

destination_root<String>

The root directory needed for some actions.

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 73

def initialize(args = [], options = {}, config = {})
  self.behavior = case config[:behavior].to_s
  when "force", "skip"
    _cleanup_options_and_set(options, config[:behavior])
    :invoke
  when "revoke"
    :revoke
  else
    :invoke
  end

  super
  self.destination_root = config[:destination_root]
end

#inject_into_class(path, klass, *args, &block)

Injects text right after the class definition. Since it depends on insert_into_file, it’s reversible.

Parameters

path<String>

path of the file to be changed

klass<String|Class>

the class to be manipulated

data<String>

the data to append to the class, can be also given as a block.

config<Hash>

give :verbose => false to not log the status.

Examples

inject_into_class "app/controllers/application_controller.rb", ApplicationController, "  filter_parameter :password\n"

inject_into_class "app/controllers/application_controller.rb", ApplicationController do
  "  filter_parameter :password\n"
end
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 210

def inject_into_class(path, klass, *args, &block)
  config = args.last.is_a?(Hash) ? args.pop : {}
  config[:after] = /class #{klass}\n|class #{klass} .*\n/
  insert_into_file(path, *(args << config), &block)
end

#inject_into_file(destination, *args, &block)

Alias for #insert_into_file.

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/inject_into_file.rb', line 29

alias_method :inject_into_file, :insert_into_file

#inject_into_module(path, module_name, *args, &block)

Injects text right after the module definition. Since it depends on insert_into_file, it’s reversible.

Parameters

path<String>

path of the file to be changed

module_name<String|Class>

the module to be manipulated

data<String>

the data to append to the class, can be also given as a block.

config<Hash>

give :verbose => false to not log the status.

Examples

inject_into_module "app/helpers/application_helper.rb", ApplicationHelper, "  def help; 'help'; end\n"

inject_into_module "app/helpers/application_helper.rb", ApplicationHelper do
  "  def help; 'help'; end\n"
end
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 233

def inject_into_module(path, module_name, *args, &block)
  config = args.last.is_a?(Hash) ? args.pop : {}
  config[:after] = /module #{module_name}\n|module #{module_name} .*\n/
  insert_into_file(path, *(args << config), &block)
end

#insert_into_file(destination, *args, &block) Also known as: #inject_into_file

Injects the given content into a file. Different from gsub_file, this method is reversible.

Parameters

destination<String>

Relative path to the destination root

data<String>

Data to add to the file. Can be given as a block.

config<Hash>

give :verbose => false to not log the status and the flag for injection (:after or :before) or :force => true for insert two or more times the same content.

Examples

insert_into_file "config/environment.rb", "config.gem :thor", :after => "Rails::Initializer.run do |config|\n"

insert_into_file "config/environment.rb", :after => "Rails::Initializer.run do |config|\n" do
  gems = ask "Which gems would you like to add?"
  gems.split(" ").map{ |gem| "  config.gem :#{gem}" }.join("\n")
end
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/inject_into_file.rb', line 24

def insert_into_file(destination, *args, &block)
  data = block_given? ? block : args.shift
  config = args.shift
  action InjectIntoFile.new(self, destination, data, config)
end

#inside(dir = "", config = {}, &block)

Do something in the root or on a provided subfolder. If a relative path is given it’s referenced from the current root. The full path is yielded to the block you provide. The path is set back to the previous path when the method exits.

Parameters

dir<String>

the directory to move to.

config<Hash>

give :verbose => true to log and use padding.

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 167

def inside(dir = "", config = {}, &block)
  verbose = config.fetch(:verbose, false)
  pretend = options[:pretend]

  say_status :inside, dir, verbose
  shell.padding += 1 if verbose
  @destination_stack.push File.expand_path(dir, destination_root)

  # If the directory doesnt exist and we're not pretending
  if !File.exist?(destination_root) && !pretend
    require "fileutils"
    FileUtils.mkdir_p(destination_root)
  end

  if pretend
    # In pretend mode, just yield down to the block
    block.arity == 1 ? yield(destination_root) : yield
  else
    require "fileutils"
    FileUtils.cd(destination_root) { block.arity == 1 ? yield(destination_root) : yield }
  end

  @destination_stack.pop
  shell.padding -= 1 if verbose
end

#prepend_file(path, *args, &block)

Alias for #prepend_to_file.

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 169

alias_method :prepend_file, :prepend_to_file

#prepend_to_file(path, *args, &block) Also known as: #prepend_file

Prepend text to a file. Since it depends on insert_into_file, it’s reversible.

Parameters

path<String>

path of the file to be changed

data<String>

the data to prepend to the file, can be also given as a block.

config<Hash>

give :verbose => false to not log the status.

Example

prepend_to_file 'config/environments/test.rb', 'config.gem "rspec"'

prepend_to_file 'config/environments/test.rb' do
  'config.gem "rspec"'
end
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 164

def prepend_to_file(path, *args, &block)
  config = args.last.is_a?(Hash) ? args.pop : {}
  config[:after] = /\A/
  insert_into_file(path, *(args << config), &block)
end

#relative_to_original_destination_root(path, remove_dot = true)

Returns the given path relative to the absolute root (ie, root where the script started).

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 115

def relative_to_original_destination_root(path, remove_dot = true)
  path = path.dup
  if path.gsub!(@destination_stack[0], ".")
    remove_dot ? (path[2..-1] || "") : path
  else
    path
  end
end

#remove_dir(path, config = {})

Alias for #remove_file.

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 328

alias_method :remove_dir, :remove_file

#remove_file(path, config = {}) Also known as: #remove_dir

Removes a file at the given location.

Parameters

path<String>

path of the file to be changed

config<Hash>

give :verbose => false to not log the status.

Example

remove_file 'README'
remove_file 'app/controllers/application_controller.rb'
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 318

def remove_file(path, config = {})
  return unless behavior == :invoke
  path = File.expand_path(path, destination_root)

  say_status :remove, relative_to_original_destination_root(path), config.fetch(:verbose, true)
  if !options[:pretend] && File.exist?(path)
    require "fileutils"
    ::FileUtils.rm_rf(path)
  end
end

#run(command, config = {})

Executes a command returning the contents of the command.

Parameters

command<String>

the command to be executed.

config<Hash>

give :verbose => false to not log the status, :capture => true to hide to output. Specify :with to append an executable to command execution.

Example

inside('vendor') do
  run('ln -s ~/edge rails')
end
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 242

def run(command, config = {})
  return unless behavior == :invoke

  destination = relative_to_original_destination_root(destination_root, false)
  desc = "#{command} from #{destination.inspect}"

  if config[:with]
    desc = "#{File.basename(config[:with].to_s)} #{desc}"
    command = "#{config[:with]} #{command}"
  end

  say_status :run, desc, config.fetch(:verbose, true)

  unless options[:pretend]
    config[:capture] ? `#{command}` : system(command.to_s)
  end
end

#run_ruby_script(command, config = {})

Executes a ruby script (taking into account WIN32 platform quirks).

Parameters

command<String>

the command to be executed.

config<Hash>

give :verbose => false to not log the status.

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 266

def run_ruby_script(command, config = {})
  return unless behavior == :invoke
  run command, config.merge(:with => Bundler::Thor::Util.ruby_command)
end

#source_paths

Holds source paths in instance so they can be manipulated.

[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 126

def source_paths
  @source_paths ||= self.class.source_paths_for_search
end

#template(source, *args, &block)

Gets an ERB template at the relative source, executes it and makes a copy at the relative destination. If the destination is not given it’s assumed to be equal to the source removing .tt from the filename.

Parameters

source<String>

the relative path to the source root.

destination<String>

the relative path to the destination root.

config<Hash>

give :verbose => false to not log the status.

Examples

template "README", "doc/README"

template "doc/README"
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 112

def template(source, *args, &block)
  config = args.last.is_a?(Hash) ? args.pop : {}
  destination = args.first || source.sub(/#{TEMPLATE_EXTNAME}$/, "")

  source  = File.expand_path(find_in_source_paths(source.to_s))
  context = config.delete(:context) || instance_eval("binding")

  create_file destination, nil, config do
    content = CapturableERB.new(::File.binread(source), nil, "-", "@output_buffer").tap do |erb|
      erb.filename = source
    end.result(context)
    content = yield(content) if block
    content
  end
end

#thor(command, *args)

Run a thor command. A hash of options can be given and it’s converted to switches.

Parameters

command<String>

the command to be invoked

args<Array>

arguments to the command

config<Hash>

give :verbose => false to not log the status, :capture => true to hide to output. Other options are given as parameter to Bundler::Thor.

Examples

thor :install, "http://gist.github.com/103208"
#=> thor install http://gist.github.com/103208

thor :list, :all => true, :substring => 'rails'
#=> thor list --all --substring=rails
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions.rb', line 289

def thor(command, *args)
  config  = args.last.is_a?(Hash) ? args.pop : {}
  verbose = config.key?(:verbose) ? config.delete(:verbose) : true
  pretend = config.key?(:pretend) ? config.delete(:pretend) : false
  capture = config.key?(:capture) ? config.delete(:capture) : false

  args.unshift(command)
  args.push Bundler::Thor::Options.to_switches(config)
  command = args.join(" ").strip

  run command, :with => :thor, :verbose => verbose, :pretend => pretend, :capture => capture
end

#uncomment_lines(path, flag, *args)

Uncomment all lines matching a given regex. It will leave the space which existed before the comment hash in tact but will remove any spacing between the comment hash and the beginning of the line.

Parameters

path<String>

path of the file to be changed

flag<Regexp|String>

the regexp or string used to decide which lines to uncomment

config<Hash>

give :verbose => false to not log the status.

Example

uncomment_lines 'config/initializers/session_store.rb', /active_record/
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 282

def uncomment_lines(path, flag, *args)
  flag = flag.respond_to?(:source) ? flag.source : flag

  gsub_file(path, /^(\s*)#[[:blank:]]*(.*#{flag})/, '\1\2', *args)
end

#with_output_buffer(buf = "".dup) (private)

This method is for internal use only.
[ GitHub ]

  
# File 'lib/bundler/vendor/thor/lib/thor/actions/file_manipulation.rb', line 343

def with_output_buffer(buf = "".dup) #:nodoc:
  raise ArgumentError, "Buffer can not be a frozen object" if buf.frozen?
  old_buffer = output_buffer
  self.output_buffer = buf
  yield
  output_buffer
ensure
  self.output_buffer = old_buffer
end