Module: Degu::HasSet::ClassMethods

Defined in:
lib/degu/has_set.rb

Instance Method Summary collapse

Instance Method Details

#has_set(set_name, options = {}) ⇒ Object

Use like this:

class Person < ActiveRecord::Base
  has_set :interests
end



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# File 'lib/degu/has_set.rb', line 16

def has_set(set_name, options = {})
  set_name_singular = set_name.to_s.singularize
  set_column = options.has_key?(:column_name) ? options[:column_name].to_s : "#{set_name}_bitfield"

  begin
    enum_class = options[:class_name] || options[:enum_class] || set_name.to_s.camelcase.constantize
  rescue NameError => ne
    raise NameError, "There ist no class to take the set entries from (#{ne.message})."
  end

  define_method("#{set_name}=") do |argument_value|
    value = nil
    unless argument_value.nil?
      value = 0
      has_set_coerce_argument_value(enum_class, argument_value).each do |set_element|
        value |= 1 << set_element.bitfield_index
      end
    end
    write_set_attribute set_column, value
  end

  define_method(set_name) do
    value = read_set_attribute(set_column) or return
    set_elements = enum_class.select do |enum_element|
      mask = 1 << enum_element.bitfield_index
      value & mask == mask
    end
    # special to_s method for element-array
    class << set_elements
      def to_s
        map(&:name) * ', '
      end
    end
    set_elements
  end

  class << self; self; end.instance_eval do
    define_method("available_#{set_name}") do
      enum_class.underscored_names.map { |name| "#{set_name_singular}_#{name}" }
    end
  end
  define_method("available_#{set_name}") do
    enum_class.underscored_names.map { |name| "#{set_name_singular}_#{name}" }
  end

  enum_class.each do |enum|
    define_method("#{set_name_singular}_#{enum.underscored_name}?") do
      mask = 1 << enum.bitfield_index
      read_set_attribute(set_column) & mask == mask
    end

    alias_method :"#{set_name_singular}_#{enum.underscored_name}", :"#{set_name_singular}_#{enum.underscored_name}?"

    define_method("#{set_name_singular}_#{enum.underscored_name}=") do |true_or_false|
      mask = 1 << enum.bitfield_index
      total_value = read_set_attribute(set_column)
      current_value = mask & total_value == mask
      true_or_false = true  if true_or_false.to_s == "true" || true_or_false.respond_to?(:to_i) && true_or_false.to_i == 1
      true_or_false = false if true_or_false.to_s == "false" || true_or_false.respond_to?(:to_i) && true_or_false.to_i == 0
      if current_value != true_or_false
        write_set_attribute set_column, true_or_false ? total_value | mask : total_value & ~mask
      end
    end
  end
end