Module: ArrayBitMask::ClassMethods

Defined in:
lib/array_bit_mask.rb

Instance Method Summary collapse

Instance Method Details

#as_bit_mask(attr, options = {}) ⇒ Object

Creates methods that accepts array of values and save them as bit mask to the attribute with an “_mask” suffix using specified source

Options

:source

Specify array of values of method name which should return an array.

:column

Specify the column which would be used to store bit mask. By default, this is an attribute with an “_mask” suffix.

Example

as_bit_mask :actions, :source => [:create, :show, :update], :column => :my_mask_column
as_bit_mask :actions, :source => :subject_actions

will save bit mask to :actions_mask attribute



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# File 'lib/array_bit_mask.rb', line 22

def as_bit_mask(attr, options={})
  return 0 unless options[:source]

  options[:column] ||= "#{attr}_mask"

  define_method "#{attr}=" do |val|
    source = bit_mask_source_for(options[:source])
    values = val.map(&:to_sym) & source
    res = self.send("#{options[:column]}=", values.map { |a| 2**source.index(a) }.inject(:+))
    instance_variable_set("@#{attr}", values)
  end

  define_method attr do
    instance_variable_get("@#{attr}") || begin
      source = bit_mask_source_for(options[:source])
      res = source.reject { |r| ((self.send(options[:column]) || 0) & 2**source.index(r)).zero? }
      instance_variable_set("@#{attr}", res)
    end
  end
end