Ruby Style Guide

Formatting

Indent with 2 spaces. NEVER USE TABS.

def good
  return true
end

Always add a trailing newline to the end of a file.

Try your best not to go over 80 character line widths.

When nesting multiple blocks, use one end per line:

def good
  example do |x|
    puts x
  end
end

Leave one newline between methods in a class. Add documentation comments for the methods in a class above where they are declared. Do not add newlines between the start of a class and the start of the first method, or the end of the last method and the end of a class.

class Format
  ##
  # Initialize with an example formatter 
  def initialize(formatter)
    @formatter = formatter
    @formatter.test!
  end

  def test(str)
    @formatter.test(str).map do |x|
      x.format!
    end
  end
end

When chaining methods on multiple lines, put the dot before the method, and indent twice:

foo.bar
    .baz
    .test
    .image
    .select{|x| x > 3}

# Always indent twice, even if the method is longer
foo.do_a_thing_with_stuff
    .another
    .even_a_bigger_thing

Conventions, Constructs, and Naming

You should never have to use a for in loop. Use constructs like .each instead.

Prefer transformations like map and select over loops.

Use snake_case for variable and method names, and CamelCase for object names. Constants should be SCREAMING_SNAKE_CASE

When working with blocks, it is okay to name the block elements with one-letter variable names, if the block is less than 3 lines long.

# good
[1,2,3].each do |x|
  print(x)
  store(x)
  dance_with(x)
end

# bad:
[1,2,3].each do |x|
  buy(x)
  use(x)
  break(x)
  fix(x)
  trash(x)
  change(x)
  mail(x)
  upgrade(x)
end

When at all possible, avoid mutating your arguments. Try to code in a semi-functional style.

Rails-Specific

Controllers

Create a helper method for the params of the model the controller deals with. Name it "#{model_name}_params". Use protected parameters in this.

Document each action

Models

Place "callbacks", "relations", "validations", "class methods", and "instance methods" all together in their own labeled blocks

Views

Views that are shared go in app/views/shared.