class OpenStruct
OpenStruct serialization/deserialization
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.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
Implementation:¶ ↑
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.
Public Class Methods
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 lib/ostruct.rb, line 87 def initialize(hash=nil) @table = {} if hash hash.each_pair do |k, v| k = k.to_sym @table[k] = v new_ostruct_member(k) end end end
Public Instance Methods
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 lib/ostruct.rb, line 265 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 lib/ostruct.rb, line 198 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 lib/ostruct.rb, line 209 def []=(name, value) modifiable[new_ostruct_member(name)] = value end
Returns a hash, that will be turned into a JSON object and represent this object.
# File ext/json/lib/json/add/ostruct.rb, line 17 def as_json(*) klass = self.class.name klass.to_s.empty? and raise JSON::JSONError, "Only named structs are supported!" { JSON.create_id => klass, 't' => table, } 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 lib/ostruct.rb, line 223 def delete_field(name) sym = name.to_sym singleton_class.__send__(:remove_method, sym, "#{sym}=") @table.delete sym 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 lib/ostruct.rb, line 127 def each_pair return to_enum(__method__) { @table.size } unless block_given? @table.each_pair{|p| yield p} 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 lib/ostruct.rb, line 275 def eql?(other) return false unless other.kind_of?(OpenStruct) @table.eql?(other.table) 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 lib/ostruct.rb, line 283 def hash @table.hash end
Duplicate an OpenStruct object members.
# File lib/ostruct.rb, line 99 def initialize_copy(orig) super @table = @table.dup @table.each_key{|key| new_ostruct_member(key)} end
Returns a string containing a detailed summary of the keys and values.
# File lib/ostruct.rb, line 234 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 lib/ostruct.rb, line 135 def marshal_dump @table end
Provides marshalling support for use by the Marshal library.
# File lib/ostruct.rb, line 142 def marshal_load(x) @table = x @table.each_key{|key| new_ostruct_member(key)} 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 lib/ostruct.rb, line 114 def to_h @table.dup end
Stores class name (OpenStruct) with this struct's values v
as a JSON string.
# File ext/json/lib/json/add/ostruct.rb, line 28 def to_json(*args) as_json.to_json(*args) end
Protected Instance Methods
Used internally to check if the OpenStruct is able to be modified before granting access to the internal Hash table to be modified.
# File lib/ostruct.rb, line 151 def modifiable begin @modifiable = true rescue raise RuntimeError, "can't modify frozen #{self.class}", caller(3) end @table end
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.
# File lib/ostruct.rb, line 166 def new_ostruct_member(name) name = name.to_sym unless respond_to?(name) define_singleton_method(name) { @table[name] } define_singleton_method("#{name}=") { |x| modifiable[name] = x } end name end