Class: OpenStruct (Ruby 2.4.2)
Description: Class : OpenStruct - Ruby 2.4.2

Support for the Ruby 2.4 series has ended. See here for reference.

### Home Classes Methods

### In Files

- ostruct.rb

### Parent

Object

### Methods

- ::new
- #==
- #[]
- #[]=
- #delete_field
- #dig
- #each_pair
- #eql?
- #freeze
- #hash
- #initialize_copy
- #inspect
- #marshal_dump
- #marshal_load
- #respond_to_missing?
- #to_h
- #to_s

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# 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.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

new(hash=nil) click to toggle source

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 89
    def initialize(hash=nil)
      @table = {}
      if hash
        hash.each_pair do |k, v|
          k = k.to_sym
          @table[k] = v
        end
      end
    end

### Public Instance Methods

==(other) click to toggle source

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 309
    def ==(other)
      return false unless other.kind_of?(OpenStruct)
      @table == other.table!
    end

[](name) click to toggle source

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 218
    def [](name)
      @table[name.to_sym]
    end

[]=(name, value) click to toggle source

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 229
    def []=(name, value)
      modifiable?[new_ostruct_member!(name)] = value
    end

delete_field(name) click to toggle source

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 261
    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

dig(name, *names) click to toggle source

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 242
    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

each_pair() click to toggle source

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 127
    def each_pair
      return to_enum(__method__) { @table.size } unless block_given?
      @table.each_pair{|p| yield p}
      self
    end

eql?(other) click to toggle source

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 319
    def eql?(other)
      return false unless other.kind_of?(OpenStruct)
      @table.eql?(other.table!)
    end

freeze() click to toggle source

                   # File ostruct.rb, line 184
    def freeze
      @table.each_key {|key| new_ostruct_member!(key)}
      super
    end

hash() click to toggle source

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 327
    def hash
      @table.hash
    end

initialize_copy(orig) click to toggle source

Duplicate an `OpenStruct` object members.

                   # File ostruct.rb, line 100
    def initialize_copy(orig)
      super
      @table = @table.dup
    end

inspect() click to toggle source

Returns a string containing a detailed summary of the keys and values.

                   # File ostruct.rb, line 277
    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

Also aliased as: to_s
marshal_dump() click to toggle source

Provides marshalling support for use by the Marshal library.

                   # File ostruct.rb, line 136
    def marshal_dump
      @table
    end

marshal_load(x) click to toggle source

Provides marshalling support for use by the Marshal library.

                   # File ostruct.rb, line 143
    def marshal_load(x)
      @table = x
    end

respond_to_missing?(mid, include_private = false) click to toggle source

                   # File ostruct.rb, line 189
    def respond_to_missing?(mid, include_private = false)
      mname = mid.to_s.chomp("=").to_sym
      @table&.key?(mname) || super
    end

to_h() click to toggle source

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 114
    def to_h
      @table.dup
    end

to_s() click to toggle source
Alias for: inspect