module Banditry

Constants

VERSION

Public Instance Methods

bandit_mask(attribute, as:, with: BanditMask) click to toggle source

Creates wrapper methods for reading, writing, and querying the bitmask stored in attribute using the class with. with defaults to Banditry::BanditMask, but you can (and probably should) define your own class inheriting from+Banditry::BanditMask to fill this role. The name of the accessor methods will be derived from as, e.g., if as is :foo, the methods will be named :foo, :foo=, and :foo?.

The reader method will return a Banditry::BanditMask representation of attribute.

The writer method overwrites the current bitmask if with an Array of bits, or it updates the current bitmask if sent an individual bit, e.g., using +#|+.

In addition to the accessor methods, a query method that delegates to Banditry::BanditMask#include? will be added.

class FileMask < Banditry::BanditMask
  bit :r, 0b001
  bit :w, 0b010
  bit :x, 0b100
end

class FileObject
  attr_accessor :mode_mask

  extend Banditry
  bandit_mask :mode_mask, as: :mode, with: FileMask
end

file = FileObject.new
file.mode_mask       # => nil
file.mode |= :r
file.mode_mask       # => 1
file.mode |= :w
file.mode_mask       # => 3
file.mode = [:r, :x]
file.mode_mask       # => 5

# File lib/banditry.rb, line 53
def bandit_mask(attribute, as:, with: BanditMask)
  class_eval do
    extend SingleForwardable

    generate_class_method as, with
    generate_reader attribute, as, with
    generate_writer attribute, as, with
    generate_query attribute, as, with
  end
end

Private Instance Methods

generate_class_method(virt, bandit) click to toggle source

# File lib/banditry.rb, line 66
def generate_class_method(virt, bandit)
  respond_to? virt and
    raise MethodCollisionError, "method `#{self}.#{virt}` already exists"

  def_single_delegator bandit, :bits, virt
end

generate_query(attr, virt, bandit) click to toggle source

# File lib/banditry.rb, line 100
def generate_query(attr, virt, bandit)
  instance_methods.include? :"#{virt}?" and
    raise MethodCollisionError, "method `#{self}##{virt}?` already exists"

  define_method :"#{virt}?" do |*bits|
    bandit.new(send(attr)).include?(*bits)
  end
end

generate_reader(attr, virt, bandit) click to toggle source

# File lib/banditry.rb, line 73
def generate_reader(attr, virt, bandit)
  instance_methods.include? virt and
    raise MethodCollisionError, "method `#{self}##{virt}` already exists"

  define_method virt do |reload = false|
    reload = true if !instance_variable_defined? :"@#{virt}"
    instance_variable_set :"@#{virt}", bandit.new(send(attr)) if reload
    instance_variable_get :"@#{virt}"
  end
end

generate_writer(attr, virt, bandit) click to toggle source

# File lib/banditry.rb, line 84
def generate_writer(attr, virt, bandit)
  instance_methods.include? :"#{virt}=" and
    raise MethodCollisionError, "method `#{self}##{virt}=` already exists"

  define_method :"#{virt}=" do |bits|
    mask = case bits
           when BanditMask
             bits
           else
             bits.inject(bandit.new) { |bm, bit| bm << bit }
           end
    send :"#{attr}=", Integer(mask)
    instance_variable_set :"@#{virt}", mask
  end
end