Collections

Collections

• Prefer map over
  collect.[link]

• Prefer detect over find. The use of find
  is ambiguous with regard to ActiveRecord’s find method - detect makes
  clear that you’re working with a Ruby collection, not an AR object.
  [link]

• Prefer reduce over inject.
  [link]

• Prefer size over either length or count
  for performance reasons.[link]

• Prefer literal array and hash creation
  notation unless you need to pass parameters to their constructors.
  [link]

  # bad
  arr = Array.new
  hash = Hash.new

  # good
  arr = []
  hash = {}

  # good because constructor requires parameters
  x = Hash.new { |h, k| h[k] = {} }

• Favor Array#join over Array#* for clarity.
  [link]

  # bad
  %w(one two three) * ', '
  # => 'one, two, three'

  # good
  %w(one two three).join(', ')
  # => 'one, two, three'

• Use symbols instead of strings as hash keys.
  [link]

  # bad
  hash = { 'one' => 1, 'two' => 2, 'three' => 3 }

  # good
  hash = { :one => 1, :two => 2, :three => 3 }

• Relatedly, use plain symbols instead of string
  symbols when possible.[link]

  # bad
  :"symbol"

  # good
  :symbol

• Use Hash#key? instead of
  Hash#has_key? and Hash#value? instead of Hash#has_value?. According
  to Matz, the longer forms are considered deprecated.
  [link]

  # bad
  hash.has_key?(:test)
  hash.has_value?(value)

  # good
  hash.key?(:test)
  hash.value?(value)

• Use multi-line hashes when it makes the code
  more readable, and use trailing commas to ensure that parameter changes
  don’t cause extraneous diff lines when the logic has not otherwise changed.
  [link]

  hash = {
    :protocol => 'https',
    :only_path => false,
    :controller => :users,
    :action => :set_password,
    :redirect => @redirect_url,
    :secret => @secret,
  }

• Use a trailing comma in an Array that
  spans more than 1 line[link]

  # good
  array = [1, 2, 3]

  # good
  array = [
    "car",
    "bear",
    "plane",
    "zoo",
  ]