MyFunnyDev

RVM (Ruby Version Manager) is a tool which lets you install and switch between multiple ruby versions. RVM has also something called Named Gem Sets. This is pretty cool because you can create many different gem sets for different types of apps. Here is how to do it (I assume you have rvm already installed if not check this out):

• go to your project folder and create new file called .rvmrc
• open .rvmrc and add rvm ruby-version@your-gem-set for example rvm ruby-1.9.1@railsgems
• close file and type: rvm gemset create your-gem-set (this will create new set)
• type gem list (you should see empty list with no gems installed)

It’s almost as you would start with a fresh system.

I wrote simple dfs in ruby:

for node:

More about gemcutter & jeweler can be found here.

Here are the steps how to publish patched gem cloned from github:

1. Append username to gem name in .gemspec or if you use jeweler open Rakefile and edit Jeweler::Tasks section save it and run:

rake gemspec

2. Build gem with:

gem build

3. Push new gem to gemcutter

gem push

Check out how Whenever gem can simplify cron configuration.

I’ve created simple rails initiator in order to start Sphinx through daemon_controller based on the Thinking Sphinx configuration. I hope it will help somebody.

require 'daemon_controller'
 
def before_start
  if not ThinkingSphinx.define_indexes?
    config = ThinkingSphinx::Configuration.instance
    cmd = "#{config.bin_path}#{config.indexer_binary_name} --config \"#{config.config_file}\" --all"
    cmd << " --rotate" if ThinkingSphinx.sphinx_running?
    system cmd
  end
end
 
if defined?(ThinkingSphinx)
  if not ThinkingSphinx.sphinx_running? 
    conf_instance = ThinkingSphinx::Configuration.instance
    @controller = DaemonController.new(
      :identifier => 'Sphinx search server',
      :start_command => "#{conf_instance.bin_path}#{conf_instance.searchd_binary_name} --pidfile --config \"#{conf_instance.config_file}\"",
      :before_start => method(:before_start),
      :ping_command => lambda { TCPSocket.new(conf_instance.configuration.searchd.address, conf_instance.configuration.searchd.port) },
      :pid_file => conf_instance.configuration.searchd.pid_file,
      :log_file => conf_instance.configuration.searchd.log)
      @controller.start
  end
end

Very often when looking at the code in rails plugins you can run into this:

module Taggable 
  def self.included(base)
    base.extend(ClassMethods)
  end
  module module ClassMethods
    #methods here
  end
end

This is a part of a bigger pattern which is shown below:

module ModuleA
  def self.included(base)
    # add class methods from ModuleB
    base.extend(ModuleB)
  end
end
 
module ModuleB
  def act_as_hello
    p "hello from module B"
  end
end
 
class ClassC
 #class body here
end
 
# include moduleA in classC
ClassC.send(:include, ModuleA)
 
class ClassD < ClassC
  act_as_hello
end
 
classD = ClassD.new

The pattern is used often when developing plugins with ActiveRecord. What we gain by inheriting from ClassC (class ClassD < ClassC) are instance methods from ModuleA. This is done by:

ClassC.send(:include, ModuleA)

Moreover since ModuleA is included in ClassC, ModuleA’s initializer def self.included(base) will be invoked at the time ModuleA is mixed with ClassC. The invocation will call base.extend(ModuleB). In this case base represents ClassC which will be extended by adding class methods from ModuleB. The ModuleA’s init method is shown again below:

def self.included(base)
  # add class methods from ModuleB to ClassC
  base.extend(ModuleB)
end

At the end our ClassD has now access to all class methods defined in ModuleB. act_as_hello will be called during ClassD initialization:

class ClassD < ClassC
  act_as_hello
end

Few nice capistrano recipes which may help you automate Ubuntu Server setup:

• ubuntu-machine
• slicehost

Interesting discussion about object decoration in ruby.

• class and instance methods
• include vs extend again

Here are few links which helped me understand few ruby concepts:

• include vs extend
• include,extend,module_eval,class_eval
• anonymous classes (aka singleton classes)
• ruby-metaprogramming-techniques