# frozen_string_literal: true # # = ostruct.rb: OpenStruct implementation # # Author:: Yukihiro Matsumoto # Documentation:: Gavin Sinclair # # OpenStruct allows the creation of data objects with arbitrary attributes. # See OpenStruct for an example. # # # An OpenStruct is a data structure, similar to a Hash, that allows the # definition of arbitrary attributes with their accompanying values. This is # accomplished by using Ruby's metaprogramming to define methods on the class # itself. # # == Examples # # require "ostruct" # # person = OpenStruct.new # person.name = "John Smith" # person.age = 70 # # person.name # => "John Smith" # person.age # => 70 # person.address # => nil # # An OpenStruct employs a Hash internally to store the attributes and values # and can even be initialized with one: # # australia = OpenStruct.new(:country => "Australia", :capital => "Canberra") # # => #<OpenStruct country="Australia", capital="Canberra"> # # Hash keys with spaces or characters that could normally not be used for # method calls (e.g. <code>()[]*</code>) will not be immediately available # on the OpenStruct object as a method for retrieval or assignment, but can # still be reached through the Object#send method or using []. # # measurements = OpenStruct.new("length (in inches)" => 24) # measurements[:"length (in inches)"] # => 24 # measurements.send("length (in inches)") # => 24 # # message = OpenStruct.new(:queued? => true) # message.queued? # => true # message.send("queued?=", false) # message.queued? # => false # # Removing the presence of an attribute requires the execution of the # delete_field method as setting the property value to +nil+ will not # remove the attribute. # # first_pet = OpenStruct.new(:name => "Rowdy", :owner => "John Smith") # second_pet = OpenStruct.new(:name => "Rowdy") # # first_pet.owner = nil # first_pet # => #<OpenStruct name="Rowdy", owner=nil> # first_pet == second_pet # => false # # first_pet.delete_field(:owner) # first_pet # => #<OpenStruct name="Rowdy"> # first_pet == second_pet # => true # # Ractor compatibility: A frozen OpenStruct with shareable values is itself shareable. # # == Caveats # # An OpenStruct utilizes Ruby's method lookup structure to find and define the # necessary methods for properties. This is accomplished through the methods # method_missing and define_singleton_method. # # This should be a consideration if there is a concern about the performance of # the objects that are created, as there is much more overhead in the setting # of these properties compared to using a Hash or a Struct. # Creating an open struct from a small Hash and accessing a few of the # entries can be 200 times slower than accessing the hash directly. # # This is a potential security issue; building OpenStruct from untrusted user data # (e.g. JSON web request) may be susceptible to a "symbol denial of service" attack # since the keys create methods and names of methods are never garbage collected. # # This may also be the source of incompatibilities between Ruby versions: # # o = OpenStruct.new # o.then # => nil in Ruby < 2.6, enumerator for Ruby >= 2.6 # # Builtin methods may be overwritten this way, which may be a source of bugs # or security issues: # # o = OpenStruct.new # o.methods # => [:to_h, :marshal_load, :marshal_dump, :each_pair, ... # o.methods = [:foo, :bar] # o.methods # => [:foo, :bar] # # To help remedy clashes, OpenStruct uses only protected/private methods ending with `!` # and defines aliases for builtin public methods by adding a `!`: # # o = OpenStruct.new(make: 'Bentley', class: :luxury) # o.class # => :luxury # o.class! # => OpenStruct # # It is recommended (but not enforced) to not use fields ending in `!`; # Note that a subclass' methods may not be overwritten, nor can OpenStruct's own methods # ending with `!`. # # For all these reasons, consider not using OpenStruct at all. # class OpenStruct VERSION = "0.3.1" # # Creates a new OpenStruct object. By default, the resulting OpenStruct # object will have no attributes. # # The optional +hash+, if given, will generate attributes and values # (can be a Hash, an OpenStruct or a Struct). # For example: # # require "ostruct" # hash = { "country" => "Australia", :capital => "Canberra" } # data = OpenStruct.new(hash) # # data # => #<OpenStruct country="Australia", capital="Canberra"> # def initialize(hash=nil) if hash update_to_values!(hash) else @table = {} end end # Duplicates an OpenStruct object's Hash table. private def initialize_clone(orig) # :nodoc: super # clones the singleton class for us @table = @table.dup unless @table.frozen? end private def initialize_dup(orig) # :nodoc: super update_to_values!(@table) end private def update_to_values!(hash) # :nodoc: @table = {} hash.each_pair do |k, v| set_ostruct_member_value!(k, v) end end # # call-seq: # ostruct.to_h -> hash # ostruct.to_h {|name, value| block } -> hash # # Converts the OpenStruct to a hash with keys representing # each attribute (as symbols) and their corresponding values. # # If a block is given, the results of the block on each pair of # the receiver will be used as pairs. # # require "ostruct" # data = OpenStruct.new("country" => "Australia", :capital => "Canberra") # data.to_h # => {:country => "Australia", :capital => "Canberra" } # data.to_h {|name, value| [name.to_s, value.upcase] } # # => {"country" => "AUSTRALIA", "capital" => "CANBERRA" } # def to_h(&block) if block @table.to_h(&block) else @table.dup end end # # :call-seq: # ostruct.each_pair {|name, value| block } -> ostruct # ostruct.each_pair -> Enumerator # # Yields all attributes (as symbols) along with the corresponding values # or returns an enumerator if no block is given. # # require "ostruct" # data = OpenStruct.new("country" => "Australia", :capital => "Canberra") # data.each_pair.to_a # => [[:country, "Australia"], [:capital, "Canberra"]] # def each_pair return to_enum(__method__) { @table.size } unless block_given? @table.each_pair{|p| yield p} self end # # Provides marshalling support for use by the Marshal library. # def marshal_dump # :nodoc: @table end # # Provides marshalling support for use by the Marshal library. # alias_method :marshal_load, :update_to_values! # :nodoc: # # Used internally to defined properties on the # OpenStruct. It does this by using the metaprogramming function # define_singleton_method for both the getter method and the setter method. # def new_ostruct_member!(name) # :nodoc: unless @table.key?(name) || is_method_protected!(name) define_singleton_method!(name) { @table[name] } define_singleton_method!("#{name}=") {|x| @table[name] = x} end end private :new_ostruct_member! private def is_method_protected!(name) # :nodoc: if !respond_to?(name, true) false elsif name.end_with?('!') true else method!(name).owner < OpenStruct end end def freeze @table.freeze super end private def method_missing(mid, *args) # :nodoc: len = args.length if mname = mid[/.*(?==\z)/m] if len != 1 raise! ArgumentError, "wrong number of arguments (given #{len}, expected 1)", caller(1) end set_ostruct_member_value!(mname, args[0]) elsif len == 0 else begin super rescue NoMethodError => err err.backtrace.shift raise! end end end # # :call-seq: # ostruct[name] -> object # # Returns the value of an attribute, or `nil` if there is no such attribute. # # require "ostruct" # person = OpenStruct.new("name" => "John Smith", "age" => 70) # person[:age] # => 70, same as person.age # def [](name) @table[name.to_sym] end # # :call-seq: # ostruct[name] = obj -> obj # # Sets the value of an attribute. # # require "ostruct" # person = OpenStruct.new("name" => "John Smith", "age" => 70) # person[:age] = 42 # equivalent to person.age = 42 # person.age # => 42 # def []=(name, value) name = name.to_sym new_ostruct_member!(name) @table[name] = value end alias_method :set_ostruct_member_value!, :[]= private :set_ostruct_member_value! # :call-seq: # ostruct.dig(name, *identifiers) -> object # # Finds and returns the object in nested objects # that is specified by +name+ and +identifiers+. # The nested objects may be instances of various classes. # See {Dig Methods}[rdoc-ref:doc/dig_methods.rdoc]. # # Examples: # require "ostruct" # address = OpenStruct.new("city" => "Anytown NC", "zip" => 12345) # person = OpenStruct.new("name" => "John Smith", "address" => address) # person.dig(:address, "zip") # => 12345 # person.dig(:business_address, "zip") # => nil def dig(name, *names) begin name = name.to_sym rescue NoMethodError raise! TypeError, "#{name} is not a symbol nor a string" end @table.dig(name, *names) end # # Removes the named field from the object. Returns the value that the field # contained if it was defined. # # require "ostruct" # # person = OpenStruct.new(name: "John", age: 70, pension: 300) # # person.delete_field!("age") # => 70 # person # => #<OpenStruct name="John", pension=300> # # Setting the value to +nil+ will not remove the attribute: # # person.pension = nil # person # => #<OpenStruct name="John", pension=nil> # def delete_field(name) sym = name.to_sym begin singleton_class.remove_method(sym, "#{sym}=") rescue NameError end @table.delete(sym) do raise! NameError.new("no field `#{sym}' in #{self}", sym) end end InspectKey = :__inspect_key__ # :nodoc: # # Returns a string containing a detailed summary of the keys and values. # def inspect ids = (Thread.current[InspectKey] ||= []) if ids.include?(object_id) detail = ' ...' else ids << object_id begin detail = @table.map do |key, value| " #{key}=#{value.inspect}" end.join(',') ensure ids.pop end end ['#<', self.class!, detail, '>'].join end alias :to_s :inspect attr_reader :table # :nodoc: alias table! table protected :table! # # Compares this object and +other+ for equality. An OpenStruct is equal to # +other+ when +other+ is an OpenStruct and the two objects' Hash tables are # equal. # # require "ostruct" # first_pet = OpenStruct.new("name" => "Rowdy") # second_pet = OpenStruct.new(:name => "Rowdy") # third_pet = OpenStruct.new("name" => "Rowdy", :age => nil) # # first_pet == second_pet # => true # first_pet == third_pet # => false # def ==(other) return false unless other.kind_of?(OpenStruct) @table == other.table! end # # Compares this object and +other+ for equality. An OpenStruct is eql? to # +other+ when +other+ is an OpenStruct and the two objects' Hash tables are # eql?. # def eql?(other) return false unless other.kind_of?(OpenStruct) @table.eql?(other.table!) end # Computes a hash code for this OpenStruct. def hash # :nodoc: @table.hash end # # Provides marshalling support for use by the YAML library. # def encode_with(coder) # :nodoc: @table.each_pair do |key, value| coder[key.to_s] = value end if @table.size == 1 && @table.key?(:table) # support for legacy format # in the very unlikely case of a single entry called 'table' coder['legacy_support!'] = true # add a bogus second entry end end # # Provides marshalling support for use by the YAML library. # def init_with(coder) # :nodoc: h = coder.map if h.size == 1 # support for legacy format key, val = h.first if key == 'table' h = val end end update_to_values!(h) end # Make all public methods (builtin or our own) accessible with `!`: instance_methods.each do |method| new_name = "#{method}!" alias_method new_name, method end # Other builtin private methods we use: alias_method :raise!, :raise private :raise! end