A singleton instance of this class is yielded by ActiveSupport::Inflector#inflections, which can then be used to specify additional inflection rules. Examples:

ActiveSupport::Inflector.inflections do |inflect|
  inflect.plural /^(ox)$/, '\1\2en'
  inflect.singular /^(ox)en/, '\1'

  inflect.irregular 'octopus', 'octopi'

  inflect.uncountable "equipment"
end

New rules are added at the top. So in the example above, the irregular rule for octopus will now be the first of the pluralization and singularization rules that is runs. This guarantees that your rules run before any of the rules that may already have been loaded.

Methods
C
H
I
N
P
S
U
Attributes
[R] humans
[R] plurals
[R] singulars
[R] uncountables
Class Public methods
instance()

Source: show 

# File activesupport/lib/active_support/inflector/inflections.rb, line 19
def self.instance
  @__instance__ ||= new
end
new()

Source: show 

# File activesupport/lib/active_support/inflector/inflections.rb, line 25
def initialize
  @plurals, @singulars, @uncountables, @humans = [], [], [], []
end
Instance Public methods
clear(scope = :all)

Clears the loaded inflections within a given scope (default is :all). Give the scope as a symbol of the inflection type, the options are: :plurals, :singulars, :uncountables, :humans.

Examples:

clear :all
clear :plurals

Source: show 

# File activesupport/lib/active_support/inflector/inflections.rb, line 96
def clear(scope = :all)
  case scope
    when :all
      @plurals, @singulars, @uncountables, @humans = [], [], [], []
    else
      instance_variable_set "@#{scope}", []
  end
end
human(rule, replacement)

Specifies a humanized form of a string by a regular expression rule or by a string mapping. When using a regular expression based replacement, the normal humanize formatting is called after the replacement. When a string is used, the human form should be specified as desired (example: ‘The name’, not ‘the_name’)

Examples:

human /_cnt$/i, '\1_count'
human "legacy_col_person_name", "Name"

Source: show 

# File activesupport/lib/active_support/inflector/inflections.rb, line 85
def human(rule, replacement)
  @humans.insert(0, [rule, replacement])
end
irregular(singular, plural)

Specifies a new irregular that applies to both pluralization and singularization at the same time. This can only be used for strings, not regular expressions. You simply pass the irregular in singular and plural form.

Examples:

irregular 'octopus', 'octopi'
irregular 'person', 'people'

Source: show 

# File activesupport/lib/active_support/inflector/inflections.rb, line 51
def irregular(singular, plural)
  @uncountables.delete(singular)
  @uncountables.delete(plural)
  if singular[0,1].upcase == plural[0,1].upcase
    plural(Regexp.new("(#{singular[0,1]})#{singular[1..-1]}$", "i"), '\1' + plural[1..-1])
    plural(Regexp.new("(#{plural[0,1]})#{plural[1..-1]}$", "i"), '\1' + plural[1..-1])
    singular(Regexp.new("(#{plural[0,1]})#{plural[1..-1]}$", "i"), '\1' + singular[1..-1])
  else
    plural(Regexp.new("#{singular[0,1].upcase}(?i)#{singular[1..-1]}$"), plural[0,1].upcase + plural[1..-1])
    plural(Regexp.new("#{singular[0,1].downcase}(?i)#{singular[1..-1]}$"), plural[0,1].downcase + plural[1..-1])
    plural(Regexp.new("#{plural[0,1].upcase}(?i)#{plural[1..-1]}$"), plural[0,1].upcase + plural[1..-1])
    plural(Regexp.new("#{plural[0,1].downcase}(?i)#{plural[1..-1]}$"), plural[0,1].downcase + plural[1..-1])
    singular(Regexp.new("#{plural[0,1].upcase}(?i)#{plural[1..-1]}$"), singular[0,1].upcase + singular[1..-1])
    singular(Regexp.new("#{plural[0,1].downcase}(?i)#{plural[1..-1]}$"), singular[0,1].downcase + singular[1..-1])
  end
end
plural(rule, replacement)

Specifies a new pluralization rule and its replacement. The rule can either be a string or a regular expression. The replacement should always be a string that may include references to the matched data from the rule.

Source: show 

# File activesupport/lib/active_support/inflector/inflections.rb, line 31
def plural(rule, replacement)
  @uncountables.delete(rule) if rule.is_a?(String)
  @uncountables.delete(replacement)
  @plurals.insert(0, [rule, replacement])
end
singular(rule, replacement)

Specifies a new singularization rule and its replacement. The rule can either be a string or a regular expression. The replacement should always be a string that may include references to the matched data from the rule.

Source: show 

# File activesupport/lib/active_support/inflector/inflections.rb, line 39
def singular(rule, replacement)
  @uncountables.delete(rule) if rule.is_a?(String)
  @uncountables.delete(replacement)
  @singulars.insert(0, [rule, replacement])
end
uncountable(*words)

Add uncountable words that shouldn’t be attempted inflected.

Examples:

uncountable "money"
uncountable "money", "information"
uncountable %w( money information rice )

Source: show 

# File activesupport/lib/active_support/inflector/inflections.rb, line 74
def uncountable(*words)
  (@uncountables << words).flatten!
end