Support for the Ruby 2.4 series has ended. See here for reference.
Object
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.
require 'ostruct' person = OpenStruct.new person.name = "John Smith" person.age = 70 person.pension = 300 puts person.name # -> "John Smith" puts person.age # -> 70 puts person.address # -> nil
An OpenStruct
employs a Hash internally to store the methods and values and can even be initialized with one:
australia = OpenStruct.new(:country => "Australia", :population => 20_000_000) p australia # -> <OpenStruct country="Australia" population=20000000>
Hash keys with spaces or characters that would normally not be able to use for method calls (e.g. ()[]*) will not be immediately available on the OpenStruct
object as a method for retrieval or assignment, but can be still be reached through the Object#send method.
measurements = OpenStruct.new("length (in inches)" => 24) measurements.send("length (in inches)") # -> 24 data_point = OpenStruct.new(:queued? => true) data_point.queued? # -> true data_point.send("queued?=",false) data_point.queued? # -> false
Removing the presence of a method requires the execution the delete_field
method as setting the property value to nil
will not remove the method.
first_pet = OpenStruct.new(:name => 'Rowdy', :owner => 'John Smith') first_pet.owner = nil second_pet = OpenStruct.new(:name => 'Rowdy') first_pet == second_pet # -> false first_pet.delete_field(:owner) first_pet == second_pet # -> true
An OpenStruct
utilizes Ruby's method lookup structure to find and define the necessary methods for properties. This is accomplished through the method method_missing and define_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.
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", :population => 20_000_000 } data = OpenStruct.new(hash) p data # -> <OpenStruct country="Australia" population=20000000>
# File ostruct.rb, line 92 def initialize(hash=nil) @table = {} if hash hash.each_pair do |k, v| k = k.to_sym @table[k] = v end end end
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.
# File ostruct.rb, line 312 def ==(other) return false unless other.kind_of?(OpenStruct) @table == other.table! end
Returns the value of a member.
person = OpenStruct.new('name' => 'John Smith', 'age' => 70) person[:age] # => 70, same as ostruct.age
# File ostruct.rb, line 221 def [](name) @table[name.to_sym] end
Sets the value of a member.
person = OpenStruct.new('name' => 'John Smith', 'age' => 70) person[:age] = 42 # => equivalent to ostruct.age = 42 person.age # => 42
# File ostruct.rb, line 232 def []=(name, value) modifiable?[new_ostruct_member!(name)] = value end
Remove the named field from the object. Returns the value that the field contained if it was defined.
require 'ostruct' person = OpenStruct.new('name' => 'John Smith', 'age' => 70) person.delete_field('name') # => 'John Smith'
# File ostruct.rb, line 264 def delete_field(name) sym = name.to_sym begin singleton_class.__send__(:remove_method, sym, "#{sym}=") rescue NameError end @table.delete(sym) do raise NameError.new("no field `#{sym}' in #{self}", sym) end end
Retrieves the value object corresponding to the each name
objects repeatedly.
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
# File ostruct.rb, line 245 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
Yields all attributes (as a symbol) along with the corresponding values or returns an enumerator if not block is given. Example:
require 'ostruct' data = OpenStruct.new("country" => "Australia", :population => 20_000_000) data.each_pair.to_a # => [[:country, "Australia"], [:population, 20000000]]
# File ostruct.rb, line 130 def each_pair return to_enum(__method__) { @table.size } unless block_given? @table.each_pair{|p| yield p} self 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?.
# File ostruct.rb, line 322 def eql?(other) return false unless other.kind_of?(OpenStruct) @table.eql?(other.table!) end
# File ostruct.rb, line 187 def freeze @table.each_key {|key| new_ostruct_member!(key)} super end
Compute a hash-code for this OpenStruct
. Two hashes with the same content will have the same hash code (and will be eql?).
# File ostruct.rb, line 330 def hash @table.hash end
Duplicate an OpenStruct
object members.
# File ostruct.rb, line 103 def initialize_copy(orig) super @table = @table.dup end
Returns a string containing a detailed summary of the keys and values.
# File ostruct.rb, line 280 def inspect str = "#<#{self.class}" ids = (Thread.current[InspectKey] ||= []) if ids.include?(object_id) return str << ' ...>' end ids << object_id begin first = true for k,v in @table str << "," unless first first = false str << " #{k}=#{v.inspect}" end return str << '>' ensure ids.pop end end
Provides marshalling support for use by the Marshal library.
# File ostruct.rb, line 139 def marshal_dump @table end
Provides marshalling support for use by the Marshal library.
# File ostruct.rb, line 146 def marshal_load(x) @table = x end
# File ostruct.rb, line 192 def respond_to_missing?(mid, include_private = false) mname = mid.to_s.chomp("=").to_sym @table.key?(mname) || super end
Converts the OpenStruct
to a hash with keys representing each attribute (as symbols) and their corresponding values Example:
require 'ostruct' data = OpenStruct.new("country" => "Australia", :population => 20_000_000) data.to_h # => {:country => "Australia", :population => 20000000 }
# File ostruct.rb, line 117 def to_h @table.dup end