Ruby on Rails, including a module with arguments - ruby-on-rails

Question

Is there a way to use arguments when including a ruby module? I have a module Assetable which is included across many classes. I want to be able to generate attr_accessor's on the fly.
module Assetable
extend ActiveSupport::Concern
included do
(argument).times do |i|
attr_accessor "asset_#{i}".to_sym
attr_accessible "asset_#{i}".to_sym
end
end
end

Answer 1

There is a trick: making a class that's inheriting from a module so that you could pass any arguments to the module like class.
class Assetable < Module
def initialize(num)
#num = num
end
def included(base)
num = #num
base.class_eval do
num.times do |i|
attr_accessor "asset_#{i}"
end
end
end
end
class A
include Assetable.new(3)
end
a = A.new
a.asset_0 = 123
a.asset_0 # => 123
The details are blogged at http://kinopyo.com/en/blog/ruby-include-module-with-arguments, hope you'll find it useful.

Answer 2

There is no way of passing arguments when including the module. The best next thing would be to define a class method that lets you create what you need afterwards:
module Assetable
extend ActiveSupport::Concern
module ClassMethods
def total_assets(number)
number.times do |i|
attr_accessor "asset_#{i}"
attr_accessible "asset_#{i}"
end
end
end
end
class C
include Assetable
total_assets 3
end
o = C.new
o.asset_2 = "Some value."
o.asset_2 #=> "Some value."
Also be careful when overriding the included method within a concern because it's also used by ActiveSupport::Concern. You should call super within the overriden method in order to ensure proper initialization.

Answer 3

You can generate and include an anonymous module without polluting global namespaces:
module Assetable
def self.[](argument)
Module.new do
extend ActiveSupport::Concern
included do
(argument).times do |i|
attr_accessor :"asset_#{i}"
attr_accessible :"asset_#{i}"
end
end
end
end
end
class Foo
include Assetable[5]
end

Answer 4

You can't pass arguments to a module. In fact, you can't pass arguments to anything except a message send.
So, you have to use a message send:
module Kernel
private def Assetable(num)
#__assetable_cache__ ||= []
#__assetable_cache__[num] ||= Module.new do
num.times do |i|
attr_accessor :"asset_#{i}"
attr_accessible :"asset_#{i}"
end
end
end
end
class Foo
include Assetable 3
end
Note: I didn't see why you would need ActiveSupport::Concern here at all, but it's easy to add back in.