Bundler 1.4.0 (still beta) can install gems in parallel, making a run of bundle install much faster.

Ruby's private keyword might do a lot less than you think.

"private" does not apply to class methods defined on self

This does not make anything private:

class Foo

  private

  def self.foo
    'foo'
  end
  
end

You need to use private_class_method instead:

class Foo

  def self.foo
    'foo'
  end
  
  private_class_method :foo
  
end

"private" does not apply to define_method

This does not make anythin...

RubyLTS is a long term supported fork of Ruby 1.8 that will continue to receive security updates for the forseeable future.

The new exception_notification has awesome options like :ignore_crawlers => true and :ignore_if => lambda { ... }. These options should be helpful in ensuring every notifications means something actionable (instead of a long log of failures that just scrolls by).

Note that you should not ignore crawlers by default. Ideally, cool URLs never change and always respond with a helpful redirect or similar.

Ignore Errors like this:

# config/initializers/exception_notification.rb

Ex...

Consul 0.9 comes with many new features to optimize powers that only check access to a given record. e.g. Power.current.post?(Post.last). See below for details.

Powers that only check a given object

Sometimes it is not convenient to define powers as a collection. Sometimes you only want to store a method that
checks whether a given object is accessible.

To do so, simply define a power that ends in a question mark:

class Power
  ...

  power :upd...

The linked page lists and explains global Ruby "dollar" variables, such as:

• $: (load path)
• $* (ARGV)
• $? (Last exit status)
• $$ (PID)
• $~ (MatchData from last successful match)
• ...and many more you'll need when reading weird code.

Regex

• $~ (last MatchData)
• $1 $2 $3 $4 (match groups from the last pattern match)
• $& (last matched string)
• $+ (last match group)
• `$`` (the string before the last match)
• $' (the string after the last match

See [this extensive list of variables](http://www.tu...

Ruby 1.9 brings a shorter way to define lambdas using the -> operator:

twice = -> (x) { 2 * x }
twice.call(5) # => 10

This is equivalent to:

twice = lambda {|x| 2 * x }
twice.call(5) # => 10

Note that the syntax is subtly different from Coffeescript where you define function parameters before the arrow: (x) -> { 2 * x }.

Using CSS sprites for background images is a technique for optimizing page load time by combining smaller images into a larger image sprite.

There are ongoing arguments on how useful this still is, as modern browsers become more comfortable to load images in parallel. However, many major websites still use them, for example amazon, [facebook](...

Did you know you can do in-place batch processing with plain ruby?

The following script will in-place replace "foo" with "bar" in all files you feed it. Call it with ./my_script path/to/my/files/*

#!ruby -i -p
$_.gsub!(/foo/, "bar")

"'-i -p" means:

Ruby will run your script once for each line in each file. The line will be placed in $_. The value of $_ at the end of your script will be written back to the file.

Shorter

Using the Kernel#gsub shorthand for $_.gsub!:

#!ruby -i -p
gsub(/foo/, "bar")

S...

This card shows how to upgrade a Rails 2 application from Rails 2.3.8 through every single patch level up to 2.3.18, and then, hopefully, Rails LTS.

2.3.8 to 2.3.9

This release has many minor changes and fixes to prepare your application for Rails 3.

Step-by-step upgrade instructions:

0. Upgrade rails gem
1. Change your environment.rb so it says RAILS_GEM_VERSION = '2.3.9'
2. Change your ...

Merge requests are often rejected for similar reasons.

To avoid this, before you send a merge request, please confirm that your code ...

• has been reviewed by yourself beforehand
• fulfills every requirement defined as an acceptance criterion
• does not have any log or debugging statements like console.log(...), byebug etc.
• has green tests
• has tests...

TLDR

Do it like this:

attribute :active, Virtus::Attribute::Boolean

Long story

In Virtus you define attribute with their type like this:

attribute :name, String
attribute :birthday, Date

When defining a boolean attributes, you will probably write it like this:

attribute :active, Boolean

The problem is, there is not actually a Boolean class in Ruby (there's only TrueClass and FalseClass), so use Virtus::Attribute::Boolean instead.

The reason whil...

Essential backports that enable many of the nice features of Ruby 1.8.7 up to 2.0.0 for earlier versions.

The Ruby on Rails security list archive can be found here: http://groups.google.com/group/rubyonrails-security

You can subscribe to this mailing list without a Google account by pasting this URL into your browser (after replacing the email address obviously).

http://groups.google.com/group/rubyonrails-security/boxsubscribe?email=your.name@example.com
                                                                       ^^^^^^^^^^^^^^^^^^^^^ <- Change this

As Bill Dueber has on his blog, you can call rvm in the shebang to select a Ruby version like this:

 #!/usr/bin/env rvm 1.9 do ruby

Standard arguments to do apply, see $> rvm help do.

Note: These instructions are for a quick per-project setup and may require you to change code. If you generally need SSL for development, you probably want to use Passenger.

1. Create a directory .ssl in your home directory. Go there and create a self-signed certificate. It is important to enter localhost.ssl as Common Name when asked. This is to mak...

• You can detect city and country from an IP address by using the GeoLite database. This is a flat file you can copy into your project (~ 20 MB).
• You can access the database using the geoip gem.
• You need to attribute MaxMind if you are using the data.
• Accuracy sort of sucks. For most countries 1/3 of addresses cannot be resolved within 40 kilometers, probably because the Inter...

When you download or upgrade RVM it has a hardcoded notion which patch level it considers to be "1.9.3".

This can give you errors like "ruby-1.9.3-p392 is not installed" even if you have another Ruby 1.9.3 that will do.

The solution is to define an alias:

rvm alias create 1.9.3 ruby-1.9.3-p385

Fuzzy matching

Another solution is to use rvm with the fuzzy flag, as stated by mpapis.

rvm use --fuzzy .

This will make rvm more intelligent in the Ruby selection. To always do fuzz...

tl;dr: Ruby's Bundler environment is passed on to system calls, which may not be what you may want as it changes gem and binary lookup. Use Bundler.with_original_env to restore the environment's state before Bundler was launched. Do this whenever you want to execute shell commands inside other bundles.

Example outline

Consider this setup:

my_project/Gemfile     # says: gem 'rails', '~> 3.0.0'
my_project/foo/Gemfile # says: gem 'rails', '~> 3.2.0'

And, just to confirm this, these are the installed Rails versions for each ...

When using the json gem, you might run into this error when using JSON.parse:

>> json = 'foo'.to_json
>> JSON.parse(json)
JSON::ParserError: 757: unexpected token at '"foo"'
	from /.../gems/json-1.7.7/lib/json/common.rb:155:in `parse'
	from /.../gems/json-1.7.7/lib/json/common.rb:155:in `parse'
	from (irb):1

Why?

The error above happens because the JSON you supplied is invalid.

While to_json does work correctly, the result itself is not JSON that can be parsed back, as that s...

All Rubyists should be familiar with the common definitions for include and extend. You include a module to add instance methods to a class and extend to add class methods. Unfortunately, this common definition isn’t entirely accurate. It fails to explain why we use instance.extend(Module) to add methods to an instance. Shouldn’t it be instance.include(Module)? To figure this out we’re going to start by discussing where methods are stored.

• include: Adds methods from the provided Module to the object
• extend: Calls include on the single...

yaml4r is a juxtaposition of yaml documents and their Ruby couterpart. Thus, it does a great job as YAML-doc, e.g. when writing Rails locale files. Did you know that ...

• << is a merge key (similar to & in SASS)
• there are variables, called aliases. Definition: &alias Some content, usage: *alias.

Caveats

Specifying a key twice does not merge the sub keys, but override the first definition, e.g.

de:
  car: # overridden
    door: Tür
 ...