Namespace
Methods
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Included Modules
Constants
MissingSourceFile = LoadError
 
HashWithIndifferentAccess = ActiveSupport::HashWithIndifferentAccess
 

Implements a hash where keys :foo and "foo" are considered to be the same.

rgb = ActiveSupport::HashWithIndifferentAccess.new

rgb[:black] = '#000000'
rgb[:black]  # => '#000000'
rgb['black'] # => '#000000'

rgb['white'] = '#FFFFFF'
rgb[:white]  # => '#FFFFFF'
rgb['white'] # => '#FFFFFF'

Internally symbols are mapped to strings when used as keys in the entire writing interface (calling []=, merge, etc). This mapping belongs to the public interface. For example, given:

hash = ActiveSupport::HashWithIndifferentAccess.new(a: 1)

You are guaranteed that the key is returned as a string:

hash.keys # => ["a"]

Technically other types of keys are accepted:

hash = ActiveSupport::HashWithIndifferentAccess.new(a: 1)
hash[0] = 0
hash # => {"a"=>1, 0=>0}

but this class is intended for use cases where strings or symbols are the expected keys and it is convenient to understand both as the same. For example the params hash in Ruby on Rails.

Note that core extensions define Hash#with_indifferent_access:

rgb = { black: '#000000', white: '#FFFFFF' }.with_indifferent_access

which may be handy.

Instance Public methods
acts_like?(duck)

A duck-type assistant method. For example, Active Support extends Date to define an acts_like_date? method, and extends Time to define acts_like_time?. As a result, we can do x.acts_like?(:time) and x.acts_like?(:date) to do duck-type-safe comparisons, since classes that we want to act like Time simply need to define an acts_like_time? method.

# File activesupport/lib/active_support/core_ext/object/acts_like.rb, line 7
def acts_like?(duck)
  respond_to? :"acts_like_#{duck}?"
end
blank?()

An object is blank if it's false, empty, or a whitespace string. For example, '', ' ', nil, [], and {} are all blank.

This simplifies

address.nil? || address.empty?

to

address.blank?

@return [true, false]

# File activesupport/lib/active_support/core_ext/object/blank.rb, line 15
def blank?
  respond_to?(:empty?) ? !!empty? : !self
end
create_fixtures(*fixture_set_names, &block)
# File railties/lib/rails/test_help.rb, line 28
def create_fixtures(*fixture_set_names, &block)
  FixtureSet.create_fixtures(ActiveSupport::TestCase.fixture_path, fixture_set_names, {}, &block)
end
deep_dup()

Returns a deep copy of object if it's duplicable. If it's not duplicable, returns self.

object = Object.new
dup    = object.deep_dup
dup.instance_variable_set(:@a, 1)

object.instance_variable_defined?(:@a) # => false
dup.instance_variable_defined?(:@a)    # => true
# File activesupport/lib/active_support/core_ext/object/deep_dup.rb, line 13
def deep_dup
  duplicable? ? dup : self
end
duplicable?()

Can you safely dup this object?

False for nil, false, true, symbol, and number objects; true otherwise.

# File activesupport/lib/active_support/core_ext/object/duplicable.rb, line 24
def duplicable?
  true
end
html_safe?()
# File activesupport/lib/active_support/core_ext/string/output_safety.rb, line 112
def html_safe?
  false
end
in?(another_object)

Returns true if this object is included in the argument. Argument must be any object which responds to #include?. Usage:

characters = ["Konata", "Kagami", "Tsukasa"]
"Konata".in?(characters) # => true

This will throw an ArgumentError if the argument doesn't respond to #include?.

# File activesupport/lib/active_support/core_ext/object/inclusion.rb, line 10
def in?(another_object)
  another_object.include?(self)
rescue NoMethodError
  raise ArgumentError.new("The parameter passed to #in? must respond to #include?")
end
instance_values()

Returns a hash with string keys that maps instance variable names without “@” to their corresponding values.

class C
  def initialize(x, y)
    @x, @y = x, y
  end
end

C.new(0, 1).instance_values # => {"x" => 0, "y" => 1}
# File activesupport/lib/active_support/core_ext/object/instance_variables.rb, line 12
def instance_values
  Hash[instance_variables.map { |name| [name[1..-1], instance_variable_get(name)] }]
end
instance_variable_names()

Returns an array of instance variable names as strings including “@”.

class C
  def initialize(x, y)
    @x, @y = x, y
  end
end

C.new(0, 1).instance_variable_names # => ["@y", "@x"]
# File activesupport/lib/active_support/core_ext/object/instance_variables.rb, line 25
def instance_variable_names
  instance_variables.map { |var| var.to_s }
end
presence()

Returns the receiver if it's present otherwise returns nil. object.presence is equivalent to

object.present? ? object : nil

For example, something like

state   = params[:state]   if params[:state].present?
country = params[:country] if params[:country].present?
region  = state || country || 'US'

becomes

region = params[:state].presence || params[:country].presence || 'US'

@return [Object]

# File activesupport/lib/active_support/core_ext/object/blank.rb, line 42
def presence
  self if present?
end
presence_in(another_object)

Returns the receiver if it's included in the argument otherwise returns nil. Argument must be any object which responds to #include?. Usage:

params[:bucket_type].presence_in %w( project calendar )

This will throw an ArgumentError if the argument doesn't respond to #include?.

@return [Object]

# File activesupport/lib/active_support/core_ext/object/inclusion.rb, line 24
def presence_in(another_object)
  self.in?(another_object) ? self : nil
end
present?()

An object is present if it's not blank.

@return [true, false]

# File activesupport/lib/active_support/core_ext/object/blank.rb, line 22
def present?
  !blank?
end
to_json_with_active_support_encoder(options = nil)
# File activesupport/lib/active_support/core_ext/object/json.rb, line 31
def to_json_with_active_support_encoder(options = nil)
  if options.is_a?(::JSON::State)
    # Called from JSON.{generate,dump}, forward it to JSON gem's to_json
    self.to_json_without_active_support_encoder(options)
  else
    # to_json is being invoked directly, use ActiveSupport's encoder
    ActiveSupport::JSON.encode(self, options)
  end
end
to_param()

Alias of to_s.

# File activesupport/lib/active_support/core_ext/object/to_param.rb, line 3
def to_param
  to_s
end
to_query(key)

Converts an object into a string suitable for use as a URL query string, using the given key as the param name.

Note: This method is defined as a default implementation for all Objects for Hash#to_query to work.

# File activesupport/lib/active_support/core_ext/object/to_query.rb, line 8
def to_query(key)
  require 'cgi' unless defined?(CGI) && defined?(CGI::escape)
  "#{CGI.escape(key.to_param)}=#{CGI.escape(to_param.to_s)}"
end
try(*a, &b)

Invokes the public method whose name goes as first argument just like public_send does, except that if the receiver does not respond to it the call returns nil rather than raising an exception.

This method is defined to be able to write

@person.try(:name)

instead of

@person ? @person.name : nil

try returns nil when called on nil regardless of whether it responds to the method:

nil.try(:to_i) # => nil, rather than 0

Arguments and blocks are forwarded to the method if invoked:

@posts.try(:each_slice, 2) do |a, b|
  ...
end

The number of arguments in the signature must match. If the object responds to the method the call is attempted and ArgumentError is still raised otherwise.

If try is called without arguments it yields the receiver to a given block unless it is nil:

@person.try do |p|
  ...
end

Please also note that try is defined on Object, therefore it won't work with instances of classes that do not have Object among their ancestors, like direct subclasses of BasicObject. For example, using try with SimpleDelegator will delegate try to the target instead of calling it on delegator itself.

# File activesupport/lib/active_support/core_ext/object/try.rb, line 41
def try(*a, &b)
  if a.empty? && block_given?
    yield self
  else
    public_send(*a, &b) if respond_to?(a.first)
  end
end
try!(*a, &b)

Same as try, but will raise a NoMethodError exception if the receiving is not nil and does not implement the tried method.

# File activesupport/lib/active_support/core_ext/object/try.rb, line 51
def try!(*a, &b)
  if a.empty? && block_given?
    yield self
  else
    public_send(*a, &b)
  end
end
unescape(str, escaped = /%[a-fA-F\d]{2}/)
# File activesupport/lib/active_support/core_ext/uri.rb, line 9
def unescape(str, escaped = /%[a-fA-F\d]{2}/)
  # TODO: Are we actually sure that ASCII == UTF-8?
  # YK: My initial experiments say yes, but let's be sure please
  enc = str.encoding
  enc = Encoding::UTF_8 if enc == Encoding::US_ASCII
  str.gsub(escaped) { [$&[1, 2].hex].pack('C') }.force_encoding(enc)
end
with_options(options)

An elegant way to factor duplication out of options passed to a series of method calls. Each method called in the block, with the block variable as the receiver, will have its options merged with the default options hash provided. Each method called on the block variable must take an options hash as its final argument.

Without with_options>, this code contains duplication:

class Account < ActiveRecord::Base
  has_many :customers, dependent: :destroy
  has_many :products,  dependent: :destroy
  has_many :invoices,  dependent: :destroy
  has_many :expenses,  dependent: :destroy
end

Using with_options, we can remove the duplication:

class Account < ActiveRecord::Base
  with_options dependent: :destroy do |assoc|
    assoc.has_many :customers
    assoc.has_many :products
    assoc.has_many :invoices
    assoc.has_many :expenses
  end
end

It can also be used with an explicit receiver:

I18n.with_options locale: user.locale, scope: 'newsletter' do |i18n|
  subject i18n.t :subject
  body    i18n.t :body, user_name: user.name
end

with_options can also be nested since the call is forwarded to its receiver. Each nesting level will merge inherited defaults in addition to their own.

# File activesupport/lib/active_support/core_ext/object/with_options.rb, line 39
def with_options(options)
  yield ActiveSupport::OptionMerger.new(self, options)
end