README.md
# <img src="https://raw.githubusercontent.com/AndyObtiva/super_module/master/SuperModule.jpg" alt="SuperModule" align="left" height="50" /> SuperModule 1.4.1
[](http://badge.fury.io/rb/super_module)
[](https://coveralls.io/r/AndyObtiva/super_module?branch=master)
[](https://codeclimate.com/github/AndyObtiva/super_module)
(Note: despite the advanced version number, the idea of super_module is highly experimental and relies heavily on meta-programming, so unless you really need it, always prefer using pure Ruby modules when sufficient)
[SuperModule](https://rubygems.org/gems/super_module) enables developers to continue to use Ruby modules as first-class citizens with mixin inheritance even when wanting to inherit singleton-class methods and invocations.
Calling [Ruby](https://www.ruby-lang.org/en/)'s [`Module#include`](http://ruby-doc.org/core-2.2.1/Module.html#method-i-include) to mix in a module does not bring in class methods by default. This can come as quite the surprise when attempting to include class methods via a module.
Ruby offers one workaround in the form of implementing the hook method [`Module.included(base)`](http://ruby-doc.org/core-2.2.1/Module.html#method-i-included) [following a certain boilerplate code idiom](http://www.railstips.org/blog/archives/2009/05/15/include-vs-extend-in-ruby/). Unfortunately, it hinders code maintainability and productivity with extra unnecessary complexity, especially in production-environment projects employing many [mixins](http://en.wikipedia.org/wiki/Mixin) (e.g. modeling business domain models with composable object [traits](http://en.wikipedia.org/wiki/Trait_(computer_programming))).
Another workaround is [`ActiveSupport::Concern`](http://api.rubyonrails.org/classes/ActiveSupport/Concern.html), a Rails library that attempts to ease some of the boilerplate pain by offering a [DSL](http://www.infoq.com/news/2007/06/dsl-or-not) layer on top of [`Module.included(base)`](http://ruby-doc.org/core-2.2.1/Module.html#method-i-included). Unfortunately, while it helps improve readability a bit, it adds even more boilerplate idiom cruft, thus feeling no more than putting a band-aid on the problem.
But do not fear, [SuperModule](https://rubygems.org/gems/super_module) comes to the rescue! By declaring your module as a SuperModule, it will simply behave as one would expect and automatically include class methods along with instance methods, without any further work needed.
Used in my other project: [Glimmer DSL for SWT](https://github.com/AndyObtiva/glimmer-dsl-swt) (JRuby Desktop Development GUI Framework)
Works in both [Ruby](https://www.ruby-lang.org) and [JRuby](https://www.jruby.org).
## Introductory Comparison
To introduce [SuperModule](https://rubygems.org/gems/super_module), here is a comparison of three different approaches for writing a
`UserIdentifiable` module, which includes ActiveModel::Model module as an in-memory alternative to `ActiveRecord::Base` superclass.
#### 1) [self.included(base)](http://ruby-doc.org/core-2.2.1/Module.html#method-i-included)
```ruby
module UserIdentifiable
include ActiveModel::Model
def self.included(base)
base.extend(ClassMethods)
base.class_eval do
belongs_to :user
validates :user_id, presence: true
end
end
module ClassMethods
def most_active_user
User.find_by_id(select('count(id) as head_count, user_id').group('user_id').order('count(id) desc').first.user_id)
end
end
def slug
"#{self.class.name}_#{user_id}"
end
end
```
This is a lot to think about and process for simply wanting inclusion of class method definitions (like <code>most_active_user</code>) and class method invocations (like <code>belongs_to</code> and <code>validates</code>). The unnecessary complexity gets in the way of problem-solving; slows down productivity with repetitive boiler-plate code; and breaks expectations set in other similar object-oriented languages, discouraging companies from including [Ruby](https://www.ruby-lang.org/en/) in a polyglot stack, such as [Groupon](http://www.groupon.com)'s [Rails/JVM/Node.js](https://engineering.groupon.com/2013/misc/i-tier-dismantling-the-monoliths/) stack and [SoundCloud](http://www.soundcloud.com)'s [JRuby/Scala/Clojure stack](https://developers.soundcloud.com/blog/building-products-at-soundcloud-part-3-microservices-in-scala-and-finagle).
#### 2) [ActiveSupport::Concern](http://api.rubyonrails.org/classes/ActiveSupport/Concern.html)
```ruby
module UserIdentifiable
extend ActiveSupport::Concern
include ActiveModel::Model
included do
belongs_to :user
validates :user_id, presence: true
end
module ClassMethods
def most_active_user
User.find_by_id(select('count(id) as head_count, user_id').group('user_id').order('count(id) desc').first.user_id)
end
end
def slug
"#{self.class.name}_#{user_id}"
end
end
```
A step forward that addresses the boiler-plate repetitive code concern, but is otherwise no more than putting a band-aid on the problem. To explain more, developer problem solving and creativity flow is still disrupted by having to think about the lower-level mechanism of running code on inclusion (using `included`) and structuring class methods in an extra sub-module (`ClassMethods`) instead of simply declaring class methods like they normally would in Ruby and staying focused on the task at hand.
#### 3) [SuperModule](https://github.com/AndyObtiva/super_module)
```ruby
module UserIdentifiable
include SuperModule
include ActiveModel::Model
belongs_to :user
validates :user_id, presence: true
def self.most_active_user
User.find_by_id(select('count(id) as head_count, user_id').group('user_id').order('count(id) desc').first.user_id)
end
def slug
"#{self.class.name}_#{user_id}"
end
end
```
By including `SuperModule` (following Ruby's basic convention of relying on a module), developers can directly add class method invocations and definitions inside the module's body, and [`SuperModule`](https://github.com/AndyObtiva/super_module) takes care of automatically mixing them into classes that include the module.
As a result, [SuperModule](https://rubygems.org/gems/super_module) collapses the difference between extending a super class and including a [super module](#glossary-and-definitions), thus encouraging developers to write simpler code while making better Object-Oriented Design decisions.
In other words, [SuperModule](https://rubygems.org/gems/super_module) furthers Ruby's goal of making programmers happy.
P.S. this library intentionally avoids bad techniques like "eval" of entire module body since they do not maintain Module mixin inheritance support. SuperModule supports full Ruby module mixin inheritance as it does not change it, yet only adds automation for singleton-class method inheritance on top of it (via surgical class_eval instead of full eval). SuperModule in fact encourages developers to continue to rely on basic Ruby code like `include SuperModule`.
## Instructions
#### 1) Install and require gem
<b>Using [Bundler](http://bundler.io/)</b>
Add the following to Gemfile: <pre>gem 'super_module', '1.4.1'</pre>
And run the following command: <pre>bundle</pre>
Afterwards, [SuperModule](https://rubygems.org/gems/super_module) will automatically get required in the application (e.g. a Rails application) and be ready for use.
<b>Using [RubyGem](https://rubygems.org/gems/super_module) Directly</b>
Run the following command: <pre>gem install super_module</pre>
(add <code>--no-ri --no-rdoc</code> if you wish to skip downloading documentation for a faster install)
Add the following at the top of your [Ruby](https://www.ruby-lang.org/en/) file: <pre>require 'super_module'</pre>
#### 2) Simply include SuperModule at the top of your module definition before anything else.
```ruby
module UserIdentifiable
include SuperModule
include ActiveModel::Model
belongs_to :user
validates :user_id, presence: true
def self.most_active_user
User.find_by_id(select('count(id) as head_count, user_id').group('user_id').order('count(id) desc').first.user_id)
end
def slug
"#{self.class.name}_#{user_id}"
end
end
```
Note: Even if you are including another [super module](#glossary-and-definitions) in your new [super module](#glossary-and-definitions), you must `include SuperModule` at the top of your module definition before anything else.
#### 3) Mix newly defined module into a class or another [super module](#glossary-and-definitions)
```ruby
class ClubParticipation < ActiveRecord::Base
include UserIdentifiable
end
class CourseEnrollment < ActiveRecord::Base
include UserIdentifiable
end
module Accountable
include SuperModule
include UserIdentifiable
end
class Activity < ActiveRecord::Base
include Accountable
end
```
#### 4) Start using by invoking class methods or instance methods
```ruby
CourseEnrollment.most_active_user
ClubParticipation.most_active_user
Activity.last.slug
ClubParticipation.create(club_id: club.id, user_id: user.id).slug
CourseEnrollment.new(course_id: course.id).valid?
```
## Usage Notes
* SuperModule must always be included at the top of a module's body at [code-time](#glossary-and-definitions)
* SuperModule inclusion can be optionally followed by other basic or [super module](#glossary-and-definitions) inclusions
* A [super module](#glossary-and-definitions) can only be included in a class or another [super module](#glossary-and-definitions)
## Glossary and Definitions
* SuperModule: name of the library and Ruby module that provides functionality via mixin
* Super module: any Ruby module that mixes in SuperModule
* Singleton class: also known as the [metaclass](https://rubymonk.com/learning/books/4-ruby-primer-ascent/chapters/39-ruby-s-object-model/lessons/131-singleton-methods-and-metaclasses) or [eigenclass](http://eigenjoy.com/2008/05/29/railsconf08-meta-programming-ruby-for-fun-and-profit/), it is the object-instance-associated class copy available to every object in Ruby (e.g. every `Object.new` instance has a singleton class that is a copy of the `Object` class, which can house instance-specific behavior if needed)
* Singleton method: an instance method defined on an object's singleton class. Often used to refer to a class or module method defined on the [Ruby class object or module object singleton class](http://ruby-doc.com/docs/ProgrammingRuby/html/classes.html) via `def self.method_name(...)` or `class << self` enclosing `def method_name(...)`
* Class method invocation: Inherited Ruby class or module method invoked in the body of a class or module (e.g. <code>validates :username, presence: true</code>)
* Code-time: Time of writing code in a Ruby file as opposed to Run-time
* Run-time: Time of executing Ruby code
## IRB Example
Create a ruby file called super_module_irb_example.rb with the following content:
```ruby
require 'rubygems' # to be backwards compatible with Ruby 1.8.7
require 'super_module'
module RequiresAttributes
include SuperModule
def self.requires(*attributes)
attributes.each {|attribute| required_attributes << attribute}
end
def self.required_attributes
@required_attributes ||= []
end
def requirements_satisfied?
!!self.class.required_attributes.reduce(true) { |result, required_attribute| result && send(required_attribute) }
end
end
class MediaAuthorization
include RequiresAttributes
attr_accessor :user_id, :credit_card_id
requires :user_id, :credit_card_id
end
```
Open `irb` ([Interactive Ruby](https://www.ruby-lang.org/en/documentation/quickstart/)) and paste the following code snippets in. You should get the output denoted by the rockets (`=>`).
```ruby
require './super_module_irb_example.rb'
```
=> true
```ruby
MediaAuthorization.required_attributes
```
=> [:user_id, :credit_card_id]
```ruby
media_authorization = MediaAuthorization.new # resulting object print-out varies
```
=> #<MediaAuthorization:0x832b36be1>
```ruby
media_authorization.requirements_satisfied?
```
=> false
```ruby
media_authorization.user_id = 387
```
=> 387
```ruby
media_authorization.requirements_satisfied?
```
=> false
```ruby
media_authorization.credit_card_id = 37
```
=> 37
```ruby
media_authorization.requirements_satisfied?
```
=> true
## Overriding `self.included(base)`
With `SuperModule`, hooking into `self.included(base)` is no longer needed for most cases. Still, there rare exceptions where that might be needed to execute some meta-programmatic logic. Fortunately, `SuperModule` offers a mechanism to do so.
`SuperModule` relies on `self.included(base)`, so modules mixing it in must refrain from implementing `self.included(base)` directly (`SuperModule` will automatically prevent that by providing instructions should one attempt to do so).
In order for a [super module](#glossary-and-definitions) to hook into `self.included(base)` and add extra logic, it must do so via `super_module_included {|base| ... }` instead, which safely appends that logic to the work of `SuperModule` as well as other nested [super module](#glossary-and-definitions)s.
Example:
```ruby
module V1::SummarizedActiveModel
include SuperModule
super_module_included do |klass|
if klass.name.split(/::/).last.start_with?('Fake')
klass.extend(FakeClassMethods1)
end
end
module FakeClassMethods1
def fake_summary
'This is a fake summary.'
end
end
class << self
def self.validates(attribute, options = {})
validations << [attribute, options]
end
def self.validations
@validations ||= []
end
def summary
validations.flatten.map(&:to_s).join("/")
end
end
end
module V1::ExtraSummarizedActiveModel
include SuperModule
include ::V1::SummarizedActiveModel
super_module_included do |klass|
if klass.name.split(/::/).last.start_with?('Fake')
klass.extend(FakeClassMethods2)
end
end
module FakeClassMethods2
def fake_extra
'This is fake extra.'
end
end
class << self
def extra
"This is extra."
end
end
end
class V1::SummarizedActiveRecord
include ::V1::SummarizedActiveModel
end
class V1::FakeSummarizedActiveRecord
include ::V1::SummarizedActiveModel
end
class V1::ExtraSummarizedActiveRecord
include ::V1::ExtraSummarizedActiveModel
end
class V1::FakeExtraSummarizedActiveRecord
include ::V1::ExtraSummarizedActiveModel
end
V1::SummarizedActiveRecord.validates 'foo', {:presence => true}
V1::SummarizedActiveRecord.validates 'bar', {:presence => true}
puts V1::SummarizedActiveRecord.summary
# prints 'foo/{:presence=>true}/bar/{:presence=>true}'
V1::FakeSummarizedActiveRecord.validates 'foo', {:presence => true}
V1::FakeSummarizedActiveRecord.validates 'bar', {:presence => true}
puts V1::FakeSummarizedActiveRecord.summary
# prints 'foo/{:presence=>true}/bar/{:presence=>true}'
puts V1::FakeSummarizedActiveRecord.fake_summary
# prints 'This is a fake summary.'
V1::ExtraSummarizedActiveRecord.validates 'foo', {:presence => true}
V1::ExtraSummarizedActiveRecord.validates 'bar', {:presence => true}
puts V1::ExtraSummarizedActiveRecord.summary
# prints 'foo/{:presence=>true}/bar/{:presence=>true}'
puts V1::ExtraSummarizedActiveRecord.extra
# prints 'This is extra.'
V1::FakeExtraSummarizedActiveRecord.validates 'foo', {:presence => true}
V1::FakeExtraSummarizedActiveRecord.validates 'bar', {:presence => true}
puts V1::FakeExtraSummarizedActiveRecord.summary
# prints 'foo/{:presence=>true}/bar/{:presence=>true}'
puts V1::FakeExtraSummarizedActiveRecord.fake_summary
# prints 'This is a fake summary.'
puts V1::FakeExtraSummarizedActiveRecord.extra
# prints 'This is extra.'
puts V1::FakeExtraSummarizedActiveRecord.fake_extra
# prints 'This is fake extra.'
```
## Limitations
[SuperModule](https://rubygems.org/gems/super_module) by definition has been designed to be used only in the initial code declaration of a module, not later mixing or re-opening of a module.
## Change Log
[CHANGELOG.md](https://github.com/AndyObtiva/super_module/blob/master/CHANGELOG.md)
## Feedback and Contribution
[SuperModule](https://rubygems.org/gems/super_module) is written in a very clean and maintainable test-first approach, so you are welcome to read through the code on GitHub for more in-depth details:
https://github.com/AndyObtiva/super_module
The library is quite new and can use all the feedback and help it can get. So, please do not hesitate to add comments if you have any, and please fork [the project on GitHub](https://github.com/AndyObtiva/super_module#fork-destination-box) in order to [make contributions via Pull Requests](https://github.com/AndyObtiva/super_module/pulls).
## Articles, Publications, and Blog Posts
* 2015-04-05 - [Ruby Weekly](http://rubyweekly.com): [Issue 240](http://rubyweekly.com/issues/240)
* 2015-03-27 - [AirPair](http://www.airpair.com) Article: [Step aside ActiveSupport::Concern. SuperModule is the new sheriff in town!](https://www.airpair.com/ruby/posts/step-aside-activesupportconcern-supermodule-is-the-new-sheriff-in-town)
* 2014-03-27 - [Code Painter](http://andymaleh.blogspot.com) Blog Post: [Ruby SuperModule Comes To The Rescue!!](http://andymaleh.blogspot.ca/2014/03/ruby-supermodule-comes-to-rescue.html)
## TODO
None
## Copyright
Copyright (c) 2014-2020 Andy Maleh. See LICENSE.txt for
further details.