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lib/ostruct.rb: [DOC] revise docs for OpenStruct
* update paragraph on implementation: define_singleton_method is used, not define_method * add call-seq with return values for each_pair * adopt description of dig from Array and Hash * fix description of the hash method * :nodoc: initialize_copy, respond_to_missing? * other small improvements, e.g. use the term `attribute' in the docs (instead of `member'), which is clearer for users of the class * improve code examples: e.g. use more consistent style (always use double quotes, drop `p' and `puts', ...), update inspect output, use example data that is not prone to change (like population) * add more code examples * fix some small errors and grammar [ruby-core:79265] [Bug #13159] git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57887 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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176
lib/ostruct.rb
176
lib/ostruct.rb
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@ -15,56 +15,58 @@
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# accomplished by using Ruby's metaprogramming to define methods on the class
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# itself.
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#
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# == Examples:
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# == Examples
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#
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# require 'ostruct'
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# require "ostruct"
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#
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# person = OpenStruct.new
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# person.name = "John Smith"
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# person.age = 70
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# person.pension = 300
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# person.name = "John Smith"
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# person.age = 70
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#
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# puts person.name # -> "John Smith"
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# puts person.age # -> 70
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# puts person.address # -> nil
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# person.name # => "John Smith"
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# person.age # => 70
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# person.address # => nil
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#
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# An OpenStruct employs a Hash internally to store the methods and values and
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# can even be initialized with one:
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# An OpenStruct employs a Hash internally to store the attributes and values
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# and can even be initialized with one:
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#
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# australia = OpenStruct.new(:country => "Australia", :population => 20_000_000)
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# p australia # -> <OpenStruct country="Australia" population=20000000>
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# australia = OpenStruct.new(:country => "Australia", :capital => "Canberra")
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# # => #<OpenStruct country="Australia", capital="Canberra">
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#
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# Hash keys with spaces or characters that would normally not be able to use for
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# method calls (e.g. ()[]*) will not be immediately available on the
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# OpenStruct object as a method for retrieval or assignment, but can be still be
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# reached through the Object#send method.
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# Hash keys with spaces or characters that could normally not be used for
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# method calls (e.g. <code>()[]*</code>) will not be immediately available
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# on the OpenStruct object as a method for retrieval or assignment, but can
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# still be reached through the Object#send method.
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#
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# measurements = OpenStruct.new("length (in inches)" => 24)
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# measurements.send("length (in inches)") # -> 24
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# measurements.send("length (in inches)") # => 24
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#
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# data_point = OpenStruct.new(:queued? => true)
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# data_point.queued? # -> true
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# data_point.send("queued?=",false)
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# data_point.queued? # -> false
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# message = OpenStruct.new(:queued? => true)
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# message.queued? # => true
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# message.send("queued?=", false)
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# message.queued? # => false
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#
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# Removing the presence of a method requires the execution the delete_field
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# method as setting the property value to +nil+ will not remove the method.
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# Removing the presence of an attribute requires the execution of the
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# delete_field method as setting the property value to +nil+ will not
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# remove the attribute.
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#
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# first_pet = OpenStruct.new(:name => "Rowdy", :owner => "John Smith")
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# second_pet = OpenStruct.new(:name => "Rowdy")
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#
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# first_pet = OpenStruct.new(:name => 'Rowdy', :owner => 'John Smith')
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# first_pet.owner = nil
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# second_pet = OpenStruct.new(:name => 'Rowdy')
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#
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# first_pet == second_pet # -> false
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# first_pet # => #<OpenStruct name="Rowdy", owner=nil>
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# first_pet == second_pet # => false
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#
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# first_pet.delete_field(:owner)
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# first_pet == second_pet # -> true
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# first_pet # => #<OpenStruct name="Rowdy">
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# first_pet == second_pet # => true
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#
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#
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# == Implementation:
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# == Implementation
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#
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# An OpenStruct utilizes Ruby's method lookup structure to find and define the
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# necessary methods for properties. This is accomplished through the method
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# method_missing and define_method.
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# necessary methods for properties. This is accomplished through the methods
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# method_missing and define_singleton_method.
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#
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# This should be a consideration if there is a concern about the performance of
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# the objects that are created, as there is much more overhead in the setting
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@ -83,11 +85,11 @@ class OpenStruct
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# (can be a Hash, an OpenStruct or a Struct).
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# For example:
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#
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# require 'ostruct'
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# hash = { "country" => "Australia", :population => 20_000_000 }
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# require "ostruct"
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# hash = { "country" => "Australia", :capital => "Canberra" }
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# data = OpenStruct.new(hash)
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#
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# p data # -> <OpenStruct country="Australia" population=20000000>
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# data # => #<OpenStruct country="Australia", capital="Canberra">
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#
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def initialize(hash=nil)
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@table = {}
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@ -99,33 +101,35 @@ class OpenStruct
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end
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end
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# Duplicate an OpenStruct object members.
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def initialize_copy(orig)
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# Duplicates an OpenStruct object's Hash table.
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def initialize_copy(orig) # :nodoc:
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super
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@table = @table.dup
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end
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#
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# Converts the OpenStruct to a hash with keys representing
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# each attribute (as symbols) and their corresponding values
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# Example:
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# each attribute (as symbols) and their corresponding values.
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#
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# require 'ostruct'
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# data = OpenStruct.new("country" => "Australia", :population => 20_000_000)
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# data.to_h # => {:country => "Australia", :population => 20000000 }
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# require "ostruct"
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# data = OpenStruct.new("country" => "Australia", :capital => "Canberra")
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# data.to_h # => {:country => "Australia", :capital => "Canberra" }
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#
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def to_h
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@table.dup
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end
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#
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# Yields all attributes (as a symbol) along with the corresponding values
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# or returns an enumerator if not block is given.
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# Example:
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# :call-seq:
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# ostruct.each_pair {|name, value| block } -> ostruct
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# ostruct.each_pair -> Enumerator
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#
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# require 'ostruct'
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# data = OpenStruct.new("country" => "Australia", :population => 20_000_000)
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# data.each_pair.to_a # => [[:country, "Australia"], [:population, 20000000]]
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# Yields all attributes (as symbols) along with the corresponding values
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# or returns an enumerator if no block is given.
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#
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# require "ostruct"
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# data = OpenStruct.new("country" => "Australia", :capital => "Canberra")
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# data.each_pair.to_a # => [[:country, "Australia"], [:capital, "Canberra"]]
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#
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def each_pair
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return to_enum(__method__) { @table.size } unless block_given?
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@ -189,7 +193,7 @@ class OpenStruct
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super
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end
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def respond_to_missing?(mid, include_private = false)
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def respond_to_missing?(mid, include_private = false) # :nodoc:
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mname = mid.to_s.chomp("=").to_sym
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@table.key?(mname) || super
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end
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@ -213,34 +217,54 @@ class OpenStruct
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end
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end
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# Returns the value of a member.
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#
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# person = OpenStruct.new('name' => 'John Smith', 'age' => 70)
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# person[:age] # => 70, same as ostruct.age
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# :call-seq:
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# ostruct[name] -> object
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#
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# Returns the value of an attribute.
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#
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# require "ostruct"
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# person = OpenStruct.new("name" => "John Smith", "age" => 70)
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# person[:age] # => 70, same as person.age
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#
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def [](name)
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@table[name.to_sym]
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end
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#
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# Sets the value of a member.
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# :call-seq:
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# ostruct[name] = obj -> obj
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#
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# person = OpenStruct.new('name' => 'John Smith', 'age' => 70)
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# person[:age] = 42 # => equivalent to ostruct.age = 42
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# person.age # => 42
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# Sets the value of an attribute.
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#
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# require "ostruct"
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# person = OpenStruct.new("name" => "John Smith", "age" => 70)
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# person[:age] = 42 # equivalent to person.age = 42
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# person.age # => 42
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#
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def []=(name, value)
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modifiable?[new_ostruct_member!(name)] = value
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end
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#
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# Retrieves the value object corresponding to the each +name+
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# objects repeatedly.
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# :call-seq:
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# ostruct.dig(name, ...) -> object
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#
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# address = OpenStruct.new('city' => "Anytown NC", 'zip' => 12345)
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# person = OpenStruct.new('name' => 'John Smith', 'address' => address)
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# person.dig(:address, 'zip') # => 12345
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# person.dig(:business_address, 'zip') # => nil
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# Extracts the nested value specified by the sequence of +name+
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# objects by calling +dig+ at each step, returning +nil+ if any
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# intermediate step is +nil+.
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#
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# require "ostruct"
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# address = OpenStruct.new("city" => "Anytown NC", "zip" => 12345)
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# person = OpenStruct.new("name" => "John Smith", "address" => address)
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#
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# person.dig(:address, "zip") # => 12345
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# person.dig(:business_address, "zip") # => nil
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#
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# data = OpenStruct.new(:array => [1, [2, 3]])
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#
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# data.dig(:array, 1, 0) # => 2
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# data.dig(:array, 0, 0) # TypeError: Integer does not have #dig method
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#
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def dig(name, *names)
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begin
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@ -252,14 +276,20 @@ class OpenStruct
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end
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#
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# Remove the named field from the object. Returns the value that the field
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# Removes the named field from the object. Returns the value that the field
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# contained if it was defined.
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#
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# require 'ostruct'
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# require "ostruct"
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#
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# person = OpenStruct.new('name' => 'John Smith', 'age' => 70)
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# person = OpenStruct.new(name: "John", age: 70, pension: 300)
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#
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# person.delete_field('name') # => 'John Smith'
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# person.delete_field("age") # => 70
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# person # => #<OpenStruct name="John", pension=300>
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#
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# Setting the value to +nil+ will not remove the attribute:
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#
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# person.pension = nil
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# person # => #<OpenStruct name="John", pension=nil>
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#
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def delete_field(name)
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sym = name.to_sym
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@ -309,6 +339,14 @@ class OpenStruct
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# +other+ when +other+ is an OpenStruct and the two objects' Hash tables are
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# equal.
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#
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# require "ostruct"
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# first_pet = OpenStruct.new("name" => "Rowdy")
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# second_pet = OpenStruct.new(:name => "Rowdy")
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# third_pet = OpenStruct.new("name" => "Rowdy", :age => nil)
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#
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# first_pet == second_pet # => true
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# first_pet == third_pet # => false
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#
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def ==(other)
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return false unless other.kind_of?(OpenStruct)
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@table == other.table!
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@ -324,9 +362,11 @@ class OpenStruct
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@table.eql?(other.table!)
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end
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# Compute a hash-code for this OpenStruct.
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# Two hashes with the same content will have the same hash code
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# (and will be eql?).
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# Computes a hash code for this OpenStruct.
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# Two OpenStruct objects with the same content will have the same hash code
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# (and will compare using #eql?).
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#
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# See also Object#hash.
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def hash
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@table.hash
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end
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