Class: Module

Inherits:
Object
  • Object
show all
Defined in:
lib/spirit_hands/mattr_accessor_with_default.rb

Instance Method Summary collapse

Instance Method Details

#mattr_accessor_with_default(property, default = nil, &block) ⇒ Object 



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# File 'lib/spirit_hands/mattr_accessor_with_default.rb', line 2

def mattr_accessor_with_default(property, default = nil, &block)
  if block_given?
    if default
      raise ArgumentError, 'Must specify only one of +default+ or &block'
    end
    default = block
  end

  getter = property.to_sym
  setter = "#{property}=".to_sym
  class_var = "@@#{property}".to_sym

  # self.property=
  define_singleton_method(setter) do |value|
    if value.nil?
      remove_class_variable(class_var)
    else
      class_variable_set(class_var, value)
    end
  end

  # self.property
  if default.respond_to?(:call) # default is callable
    define_singleton_method(getter) do
      if class_variable_defined?(class_var)
        class_variable_get(class_var)
      else
        default.()
      end
    end
  else # default is literal object
    default_value_name = "DEFAULT_#{property}".upcase.to_sym
    const_set(default_value_name, default)
    define_singleton_method(getter) do
      if class_variable_defined?(class_var)
        class_variable_get(class_var)
      else
        const_get(default_value_name)
      end
    end
  end
end