Class: Class

Inherits:
Object
  • Object
show all
Defined in:
lib/autumn/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/autumn/inheritable_attributes.rb', line 98

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/autumn/inheritable_attributes.rb', line 103

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/autumn/inheritable_attributes.rb', line 64

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)
        write_inheritable_array(:#{sym}, obj)
      end

      #{"
      def #{sym}=(obj)
        self.class.#{sym} = obj
      end
      " unless options[:instance_writer] == false }
    EOS
  end
end

#class_inheritable_hash(*syms) ⇒ Object 



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

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/autumn/inheritable_attributes.rb', line 81

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)
        write_inheritable_hash(:#{sym}, obj)
      end

      #{"
      def #{sym}=(obj)
        self.class.#{sym} = obj
      end
      " unless options[:instance_writer] == false }
    EOS
  end
end

#class_inheritable_reader(*syms) ⇒ Object

:nodoc:



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# File 'lib/autumn/inheritable_attributes.rb', line 32

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

      def #{sym}
        self.class.#{sym}
      end
    EOS
  end
end

#class_inheritable_writer(*syms) ⇒ Object 



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# File 'lib/autumn/inheritable_attributes.rb', line 47

def class_inheritable_writer(*syms)
  options = syms.last.is_a?(Hash) ? syms.pop : {}
  syms.each do |sym|
    class_eval <<-EOS
      def self.#{sym}=(obj)
        write_inheritable_attribute(:#{sym}, obj)
      end

      #{"
      def #{sym}=(obj)
        self.class.#{sym} = obj
      end
      " unless options[:instance_writer] == false }
    EOS
  end
end

#inheritable_attributes ⇒ Object 



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# File 'lib/autumn/inheritable_attributes.rb', line 113

def inheritable_attributes
  @inheritable_attributes ||= EMPTY_INHERITABLE_ATTRIBUTES
end

#read_inheritable_attribute(key) ⇒ Object 



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# File 'lib/autumn/inheritable_attributes.rb', line 134

def read_inheritable_attribute(key)
  inheritable_attributes[key]
end

#reset_inheritable_attributes ⇒ Object 



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# File 'lib/autumn/inheritable_attributes.rb', line 138

def reset_inheritable_attributes
  @inheritable_attributes = EMPTY_INHERITABLE_ATTRIBUTES
end

#write_inheritable_array(key, elements) ⇒ Object 



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# File 'lib/autumn/inheritable_attributes.rb', line 124

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/autumn/inheritable_attributes.rb', line 117

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/autumn/inheritable_attributes.rb', line 129

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