Class: Class

Inherits:
Object
  • Object
show all
Defined in:
lib/core_ext/class.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

#cattr_accessor(*syms) ⇒ Object 



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# File 'lib/core_ext/class.rb', line 46

def cattr_accessor(*syms)
  cattr_reader(*syms)
  cattr_writer(*syms)
end

#cattr_reader(*syms) ⇒ Object

:nodoc:



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

def cattr_reader(*syms)
  syms.flatten.each do |sym|
    next if sym.is_a?(Hash)
    class_eval(<<-EOS, __FILE__, __LINE__)
      unless defined? @@#{sym}
        @@#{sym} = nil
      end

      def self.#{sym}
        @@#{sym}
      end

      def #{sym}
        @@#{sym}
      end
    EOS
  end
end

#cattr_writer(*syms) ⇒ Object 



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# File 'lib/core_ext/class.rb', line 25

def cattr_writer(*syms)
  options = syms.last.is_a?(Hash) ? syms.pop : {}
  syms.flatten.each do |sym|
    class_eval(<<-EOS, __FILE__, __LINE__)
      unless defined? @@#{sym}
        @@#{sym} = nil
      end

      def self.#{sym}=(obj)
        @@#{sym} = obj
      end

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

#class_inheritable_accessor(*syms) ⇒ Object 



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# File 'lib/core_ext/class.rb', line 116

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/class.rb', line 121

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/class.rb', line 82

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/core_ext/class.rb', line 126

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/class.rb', line 99

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 



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# File 'lib/core_ext/class.rb', line 50

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/core_ext/class.rb', line 65

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/core_ext/class.rb', line 131

def inheritable_attributes
  @inheritable_attributes ||= EMPTY_INHERITABLE_ATTRIBUTES
end

#read_inheritable_attribute(key) ⇒ Object 



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# File 'lib/core_ext/class.rb', line 152

def read_inheritable_attribute(key)
  inheritable_attributes[key]
end

#reset_inheritable_attributes ⇒ Object 



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# File 'lib/core_ext/class.rb', line 156

def reset_inheritable_attributes
  @inheritable_attributes = EMPTY_INHERITABLE_ATTRIBUTES
end

#write_inheritable_array(key, elements) ⇒ Object 



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# File 'lib/core_ext/class.rb', line 142

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/class.rb', line 135

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/class.rb', line 147

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