Module: LittleGhost::Support::ClassAttributes

Included in:
Agent, Tool
Defined in:
lib/little_ghost/support/class_attributes.rb

Overview

ClassAttributes gives framework extension classes small, thread-safe, inheritable settings. A subclass inherits a value until it assigns its own; mutable defaults are not duplicated automatically.

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(base) ⇒ Object

:nodoc:



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# File 'lib/little_ghost/support/class_attributes.rb', line 9

def self.included(base) # :nodoc:
  base.extend(self)
end

Instance Method Details

#class_attribute(*names, default: nil) ⇒ Object

Defines thread-safe singleton readers and writers for names.



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# File 'lib/little_ghost/support/class_attributes.rb', line 14

def class_attribute(*names, default: nil)
  names.each do |name|
    unless name.is_a?(String) || name.is_a?(Symbol)
      raise TypeError, "#{name.inspect} is not a symbol nor a string"
    end

    name = name.to_sym
    singleton_class.remove_method(name) if singleton_class.method_defined?(name, false)
    writer = :"#{name}="
    singleton_class.remove_method(writer) if singleton_class.method_defined?(writer, false)
    values = {self => default}
    mutex = Mutex.new
    define_singleton_method(name) do
      found, value = mutex.synchronize { [values.key?(self), values[self]] }
      return value if found

      superclass.public_send(name)
    end
    define_singleton_method(writer) do |value|
      mutex.synchronize { values[self] = value }
      value
    end
  end
end