Class: OpenStruct
- Inherits:
-
Object
- Object
- OpenStruct
- Defined in:
- lib/rubysl/ostruct/ostruct.rb
Overview
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.
Constant Summary collapse
- InspectKey =
:nodoc:
:__inspect_key__
Instance Method Summary collapse
-
#==(other) ⇒ Object
Compares this object and
other
for equality. -
#[](name) ⇒ Object
Returns the value of a member.
-
#[]=(name, value) ⇒ Object
Sets the value of a member.
-
#delete_field(name) ⇒ Object
Remove the named field from the object.
-
#each_pair ⇒ Object
Yields all attributes (as a symbol) along with the corresponding values or returns an enumerator if not block is given.
-
#eql?(other) ⇒ Boolean
Compares this object and
other
for equality. -
#hash ⇒ Object
Compute a hash-code for this OpenStruct.
-
#initialize(hash = nil) ⇒ OpenStruct
constructor
Creates a new OpenStruct object.
-
#initialize_copy(orig) ⇒ Object
Duplicate an OpenStruct object members.
-
#inspect ⇒ Object
(also: #to_s)
Returns a string containing a detailed summary of the keys and values.
-
#marshal_dump ⇒ Object
Provides marshalling support for use by the Marshal library.
-
#marshal_load(x) ⇒ Object
Provides marshalling support for use by the Marshal library.
-
#method_missing(mid, *args) ⇒ Object
:nodoc:.
-
#to_h ⇒ Object
Converts the OpenStruct to a hash with keys representing each attribute (as symbols) and their corresponding values Example:.
Constructor Details
#initialize(hash = nil) ⇒ OpenStruct
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>
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# File 'lib/rubysl/ostruct/ostruct.rb', line 87 def initialize(hash=nil) @table = {} if hash hash.each_pair do |k, v| @table[k.to_sym] = v new_ostruct_member(k) end end end |
Dynamic Method Handling
This class handles dynamic methods through the method_missing method
#method_missing(mid, *args) ⇒ Object
:nodoc:
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# File 'lib/rubysl/ostruct/ostruct.rb', line 175 def method_missing(mid, *args) # :nodoc: mname = mid.id2name len = args.length if mname.chomp!('=') if len != 1 raise ArgumentError, "wrong number of arguments (#{len} for 1)", caller(1) end modifiable[new_ostruct_member(mname)] = args[0] elsif len == 0 @table[mid] else raise NoMethodError, "undefined method `#{mid}' for #{self}", caller(1) end end |
Instance Method Details
#==(other) ⇒ Object
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.
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# File 'lib/rubysl/ostruct/ostruct.rb', line 262 def ==(other) return false unless other.kind_of?(OpenStruct) @table == other.table end |
#[](name) ⇒ Object
Returns the value of a member.
person = OpenStruct.new('name' => 'John Smith', 'age' => 70)
person[:age] # => 70, same as ostruct.age
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# File 'lib/rubysl/ostruct/ostruct.rb', line 195 def [](name) @table[name.to_sym] end |
#[]=(name, value) ⇒ Object
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
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# File 'lib/rubysl/ostruct/ostruct.rb', line 206 def []=(name, value) modifiable[new_ostruct_member(name)] = value end |
#delete_field(name) ⇒ Object
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'
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# File 'lib/rubysl/ostruct/ostruct.rb', line 220 def delete_field(name) sym = name.to_sym singleton_class.__send__(:remove_method, sym, "#{name}=") @table.delete sym end |
#each_pair ⇒ Object
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]]
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# File 'lib/rubysl/ostruct/ostruct.rb', line 126 def each_pair return to_enum __method__ unless block_given? @table.each_pair { |p| yield p } end |
#eql?(other) ⇒ Boolean
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?.
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# File 'lib/rubysl/ostruct/ostruct.rb', line 272 def eql?(other) return false unless other.kind_of?(OpenStruct) @table.eql?(other.table) end |
#hash ⇒ Object
Compute a hash-code for this OpenStruct. Two hashes with the same content will have the same hash code (and will be eql?).
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# File 'lib/rubysl/ostruct/ostruct.rb', line 280 def hash @table.hash end |
#initialize_copy(orig) ⇒ Object
Duplicate an OpenStruct object members.
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# File 'lib/rubysl/ostruct/ostruct.rb', line 98 def initialize_copy(orig) super @table = @table.dup @table.each_key { |key| new_ostruct_member(key) } end |
#inspect ⇒ Object Also known as: to_s
Returns a string containing a detailed summary of the keys and values.
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# File 'lib/rubysl/ostruct/ostruct.rb', line 231 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 |
#marshal_dump ⇒ Object
Provides marshalling support for use by the Marshal library.
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# File 'lib/rubysl/ostruct/ostruct.rb', line 134 def marshal_dump @table end |
#marshal_load(x) ⇒ Object
Provides marshalling support for use by the Marshal library.
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# File 'lib/rubysl/ostruct/ostruct.rb', line 141 def marshal_load(x) @table = x @table.each_key{|key| new_ostruct_member(key)} end |
#to_h ⇒ Object
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 }
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# File 'lib/rubysl/ostruct/ostruct.rb', line 113 def to_h @table.dup end |