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class OpenStruct
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. ()[]*
) 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.
measurements = OpenStruct.new("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
Implementation
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
.
Public Class Methods
# File lib/ostruct.rb, line 91
def initialize(hash=nil)
@table = {}
if hash
hash.each_pair do |k, v|
k = k.to_sym
@table[k] = v
end
end
end
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">
Public Instance Methods
# File lib/ostruct.rb, line 359
def ==(other)
return false unless other.kind_of?(OpenStruct)
@table == other.table!
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.
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
# File lib/ostruct.rb, line 244
def [](name)
@table[name.to_sym]
end
Returns the value of an attribute.
require "ostruct"
person = OpenStruct.new("name" => "John Smith", "age" => 70)
person[:age] # => 70, same as person.age
# File lib/ostruct.rb, line 259
def []=(name, value)
modifiable?[new_ostruct_member!(name)] = value
end
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
# 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
Returns a hash, that will be turned into a JSON
object and represent this object.
# File lib/ostruct.rb, line 308
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
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>
# File lib/ostruct.rb, line 283
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
Extracts the nested value specified by the sequence of name
objects by calling dig
at each step, returning nil
if any intermediate step is nil
.
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
data = OpenStruct.new(:array => [1, [2, 3]])
data.dig(:array, 1, 0) # => 2
data.dig(:array, 0, 0) # TypeError: Integer does not have #dig method
# File lib/ostruct.rb, line 144
def each_pair
return to_enum(__method__) { @table.size } unless block_given?
@table.each_pair{|p| yield p}
self
end
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"]]
# File lib/ostruct.rb, line 369
def eql?(other)
return false unless other.kind_of?(OpenStruct)
@table.eql?(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?.
# File lib/ostruct.rb, line 202
def freeze
@table.each_key {|key| new_ostruct_member!(key)}
super
end
Object#freeze
# File lib/ostruct.rb, line 379
def hash
@table.hash
end
Computes a hash code for this OpenStruct
. Two OpenStruct
objects with the same content will have the same hash code (and will compare using eql?
).
See also Object#hash.
# File lib/ostruct.rb, line 324
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
Returns a string containing a detailed summary of the keys and values.
# File lib/ostruct.rb, line 153
def marshal_dump
@table
end
Provides marshalling support for use by the Marshal
library.
# File lib/ostruct.rb, line 160
def marshal_load(x)
@table = x
end
Provides marshalling support for use by the Marshal
library.
# File lib/ostruct.rb, line 124
def to_h(&block)
if block_given?
@table.to_h(&block)
else
@table.dup
end
end
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" }
# File ext/json/lib/json/add/ostruct.rb, line 28
def to_json(*args)
as_json.to_json(*args)
end
Stores class name (OpenStruct) with this struct's values v
as a JSON
string.
Ruby Core © 1993–2017 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.