Class: Class

Inherits:
Object
  • Object
show all
Defined in:
lib/core_ext/delegating_attributes.rb,
lib/core_ext/inheritable_attributes.rb

Overview

Allows attributes to be shared within an inheritance hierarchy, but where each descendant gets a copy of their parents’ attributes, instead of just a pointer to the same. This means that the child can add elements to, for example, an array without those additions being shared with either their parent, siblings, or children, which is unlike the regular class-level attributes that are shared across the entire hierarchy.

Constant Summary collapse

EMPTY_INHERITABLE_ATTRIBUTES =

Prevent this constant from being created multiple times

{}.freeze

Instance Method Summary collapse

Instance Method Details

#class_inheritable_accessor(*syms) ⇒ Object 



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# File 'lib/core_ext/inheritable_attributes.rb', line 72

def class_inheritable_accessor(*syms)
  class_inheritable_reader(*syms)
  class_inheritable_writer(*syms)
end

#class_inheritable_array(*syms) ⇒ Object 



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# File 'lib/core_ext/inheritable_attributes.rb', line 77

def class_inheritable_array(*syms)
  class_inheritable_reader(*syms)
  class_inheritable_array_writer(*syms)
end

#class_inheritable_array_writer(*syms) ⇒ Object 



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# File 'lib/core_ext/inheritable_attributes.rb', line 38

def class_inheritable_array_writer(*syms)
  options = syms.last.is_a?(::Hash) ? syms.pop : {}
  syms.each do |sym|
    class_eval <<-EOS
      def self.#{sym}=(obj)                          # def self.levels=(obj)
        write_inheritable_array(:#{sym}, obj)        #   write_inheritable_array(:levels, obj)
      end                                            # end
                                                     #
      #{"                                            #
      def #{sym}=(obj)                               # def levels=(obj)
        self.class.#{sym} = obj                      #   self.class.levels = obj
      end                                            # end
      " unless options[:instance_writer] == false }  # # the writer above is generated unless options[:instance_writer] == false
    EOS
  end
end

#class_inheritable_hash(*syms) ⇒ Object 



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# File 'lib/core_ext/inheritable_attributes.rb', line 82

def class_inheritable_hash(*syms)
  class_inheritable_reader(*syms)
  class_inheritable_hash_writer(*syms)
end

#class_inheritable_hash_writer(*syms) ⇒ Object 



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# File 'lib/core_ext/inheritable_attributes.rb', line 55

def class_inheritable_hash_writer(*syms)
  options = syms.last.is_a?(::Hash) ? syms.pop : {}
  syms.each do |sym|
    class_eval <<-EOS
      def self.#{sym}=(obj)                          # def self.nicknames=(obj)
        write_inheritable_hash(:#{sym}, obj)         #   write_inheritable_hash(:nicknames, obj)
      end                                            # end
                                                     #
      #{"                                            #
      def #{sym}=(obj)                               # def nicknames=(obj)
        self.class.#{sym} = obj                      #   self.class.nicknames = obj
      end                                            # end
      " unless options[:instance_writer] == false }  # # the writer above is generated unless options[:instance_writer] == false
    EOS
  end
end

#class_inheritable_reader(*syms) ⇒ Object

:nodoc:



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# File 'lib/core_ext/inheritable_attributes.rb', line 6

def class_inheritable_reader(*syms)
  syms.each do |sym|
    next if sym.is_a?(Hash)
    class_eval <<-EOS
      def self.#{sym}                        # def self.before_add_for_comments
        read_inheritable_attribute(:#{sym})  #   read_inheritable_attribute(:before_add_for_comments)
      end                                    # end
                                             #
      def #{sym}                             # def before_add_for_comments
        self.class.#{sym}                    #   self.class.before_add_for_comments
      end                                    # end
    EOS
  end
end

#class_inheritable_writer(*syms) ⇒ Object 



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# File 'lib/core_ext/inheritable_attributes.rb', line 21

def class_inheritable_writer(*syms)
  options = syms.last.is_a?(::Hash) ? syms.pop : {}
  syms.each do |sym|
    class_eval <<-EOS
      def self.#{sym}=(obj)                          # def self.color=(obj)
        write_inheritable_attribute(:#{sym}, obj)    #   write_inheritable_attribute(:color, obj)
      end                                            # end
                                                     #
      #{"                                            #
      def #{sym}=(obj)                               # def color=(obj)
        self.class.#{sym} = obj                      #   self.class.color = obj
      end                                            # end
      " unless options[:instance_writer] == false }  # # the writer above is generated unless options[:instance_writer] == false
    EOS
  end
end

#inheritable_attributes ⇒ Object 



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# File 'lib/core_ext/inheritable_attributes.rb', line 87

def inheritable_attributes
  @inheritable_attributes ||= EMPTY_INHERITABLE_ATTRIBUTES
end

#read_inheritable_attribute(key) ⇒ Object 



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# File 'lib/core_ext/inheritable_attributes.rb', line 108

def read_inheritable_attribute(key)
  inheritable_attributes[key]
end

#reset_inheritable_attributes ⇒ Object 



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# File 'lib/core_ext/inheritable_attributes.rb', line 112

def reset_inheritable_attributes
  @inheritable_attributes = EMPTY_INHERITABLE_ATTRIBUTES
end

#superclass_delegating_accessor(*names) ⇒ Object 



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# File 'lib/core_ext/delegating_attributes.rb', line 71

def superclass_delegating_accessor(*names)
  superclass_delegating_reader(*names)
  superclass_delegating_writer(*names)
end

#superclass_delegating_reader(*names) ⇒ Object 



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# File 'lib/core_ext/delegating_attributes.rb', line 32

def superclass_delegating_reader(*names)
  class_name_to_stop_searching_on = self.superclass.name.blank? ? "Object" : self.superclass.name
  names.each do |name|
    class_eval <<-EOS
    def self.#{name}                                            # def self.only_reader
      if defined?(@#{name})                                     #   if defined?(@only_reader)
        @#{name}                                                #     @only_reader
      elsif superclass < #{class_name_to_stop_searching_on} &&  #   elsif superclass < Object &&
            superclass.respond_to?(:#{name})                    #         superclass.respond_to?(:only_reader)
        superclass.#{name}                                      #     superclass.only_reader
      end                                                       #   end
    end                                                         # end
    def #{name}                                                 # def only_reader
      self.class.#{name}                                        #   self.class.only_reader
    end                                                         # end
    def self.#{name}?                                           # def self.only_reader?
      !!#{name}                                                 #   !!only_reader
    end                                                         # end
    def #{name}?                                                # def only_reader?
      !!#{name}                                                 #   !!only_reader
    end                                                         # end
    EOS
  end
end

#superclass_delegating_writer(*names) ⇒ Object 



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# File 'lib/core_ext/delegating_attributes.rb', line 59

def superclass_delegating_writer(*names)
  names.each do |name|
    class_eval <<-EOS
      def self.#{name}=(value)  # def self.only_writer=(value)
        @#{name} = value        #   @only_writer = value
      end                       # end
    EOS
  end
end

#write_inheritable_array(key, elements) ⇒ Object 



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# File 'lib/core_ext/inheritable_attributes.rb', line 98

def write_inheritable_array(key, elements)
  write_inheritable_attribute(key, []) if read_inheritable_attribute(key).nil?
  write_inheritable_attribute(key, read_inheritable_attribute(key) + elements)
end

#write_inheritable_attribute(key, value) ⇒ Object 



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# File 'lib/core_ext/inheritable_attributes.rb', line 91

def write_inheritable_attribute(key, value)
  if inheritable_attributes.equal?(EMPTY_INHERITABLE_ATTRIBUTES)
    @inheritable_attributes = {}
  end
  inheritable_attributes[key] = value
end

#write_inheritable_hash(key, hash) ⇒ Object 



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# File 'lib/core_ext/inheritable_attributes.rb', line 103

def write_inheritable_hash(key, hash)
  write_inheritable_attribute(key, {}) if read_inheritable_attribute(key).nil?
  write_inheritable_attribute(key, read_inheritable_attribute(key).merge(hash))
end