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magic_numbers.rb
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magic_numbers.rb
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module MagicNumbers
module ActiveRecord
extend ActiveSupport::Concern
module ClassMethods
def enum_attribute(name, values, options = {})
magic_number_attribute(name, options.merge({
:values => values,
:type => :enum
}))
end
def bitfield_attribute(name, values, options = {})
magic_number_attribute(name, options.merge({
:values => values,
:type => :bitfield
}))
end
def magic_number_values(name)
magic_number_options(name)[:values]
end
def magic_number_for(name, value)
options = self.magic_number_options(name)
values, offset = options[:values], options[:offset] || 0
value = value.is_a?(Array) ? value.map(&:to_s) : value.to_s
if options[:type] == :bitfield
(values & value).map { |v| 2**values.index(v) }.sum
else
(values.index(value) + offset) || options[:default]
end
end
def magic_number_options(name)
read_inheritable_attribute(:magic_number_attributes)[name]
end
protected
def magic_number_attribute(name, options)
options.assert_valid_keys(:values, :type, :default, :column, :offset)
options[:values].map!(&:to_s)
options[:column] = name unless options[:column].present?
magic_number_attributes = read_inheritable_attribute(:magic_number_attributes) || {}
magic_number_attributes[name] = options
write_inheritable_attribute(:magic_number_attributes, magic_number_attributes)
class_eval <<-EOE
def #{name}; magic_number_read(:#{name}); end
def #{name}=(new_value); magic_number_write(:#{name}, new_value); end
def self.#{name}_values; magic_number_values(:#{name}); end
EOE
end
end
module InstanceMethods
def magic_number_read(name)
options = self.class.magic_number_options(name)
values, offset = options[:values], options[:offset] || 0
mask_value = self[options[:column]]
if options[:type] == :bitfield
result = values.reject { |r| ((mask_value || 0) & 2**values.index(r)).zero? }
else
(mask_value && values[mask_value - offset].try(:to_sym))
end
end
def magic_number_write(name, new_value)
options = self.class.magic_number_options(name)
self[options[:column]] = self.class.magic_number_for(name, new_value)
end
end
end
end
ActiveRecord::Base.send(:include, MagicNumbers::ActiveRecord)