inoculate

Inoculate

Inoculate is a small, thread-safe dependency injection library configured entirely with Ruby. It provides several life-cycles and provides dependency access through private accessors.

What's in the box?

✅ Simple usage documentation written to get started fast. Check it out!

📚 YARD generated API documentation for the library. Check it out!

🤖 RBS types for your type checking wants. Check it out!

💎 Tests against many Ruby versions. Check it out!

🔒 MFA protection on all gem owners. Check it out!

• Quick Start
• Usage
  • Dependency Life Cycles
    • Transient
    • Instance
    • Singleton
  • Renaming the Declaration API
  • Hide Your Dependency on Inoculate
• Installation
  • Supported Ruby Versions

Quick Start

Create an initialization file for your dependencies and start registering them.

require "inoculate"

Inoculate.initialize do |config|
  config.transient(:counter) { Counter.new }
end

To take advantage of dependency injection in tests, initialize based on the run-time environment.

# config/environments/test.rb
require "inoculate"

Inoculate.initialize do |config|
  config.transient(:counter) { instance_double(Counter) }
end

Finally, declare your dependencies (which are injected as included modules).

require "inoculate"

class HistogramGraph
  include Inoculate::Porter
  inoculate_with :counter
  
  def to_s
    counter.to_s
  end
end

Usage

Dependency Life Cycles

Transient

Transient dependencies are constructed for each call of the dependency method.

class Counter
   attr_reader :count

   def initialize
      @count = 0
   end
   
   def inc
      @count += 1
   end
end

Inoculate.initialize do |config|
   config.transient(:counter) { Counter.new }
end

class Example
   include Inoculate::Porter
   inoculate_with :counter
   
   def to_s
      counter.inc
      "Count is: #{counter.count}"
   end
end

a = Example.new
puts a, a, a

This results in:

Count is: 0
Count is: 0
Count is: 0
=> nil    

Instance

Instance dependencies are constructed once for each instance of a dependent class.

class Counter
   attr_reader :count

   def initialize
      @count = 0
   end
   
   def inc
      @count += 1
   end
end

Inoculate.initialize do |config|
   config.instance(:counter) { Counter.new }
end

class Example
   include Inoculate::Porter
   inoculate_with :counter
   
   def initialize(name)
      @name = name
   end
   
   def to_s
      counter.inc
      "[#{@name}] Count is: #{counter.count}"
   end
end

a = Example.new("a")
b = Example.new("b")
puts a, a, b

This results in:

[a] Count is: 1
[a] Count is: 2
[b] Count is: 1
=> nil  

Singleton

Singleton dependencies are constructed once.

class Counter
   attr_reader :count

   def initialize
      @count = 0
   end
   
   def inc
      @count += 1
   end
end

Inoculate.initialize do |config|
   config.singleton(:counter) { Counter.new }
end

class Example
   include Inoculate::Porter
   inoculate_with :counter
   
   def initialize(name)
      @name = name
   end
   
   def to_s
      counter.inc
      "[#{@name}] Count is: #{counter.count}"
   end
end

a = Example.new("a")
b = Example.new("b")
puts a, a, b

This results in:

[a] Count is: 1
[a] Count is: 2                         
[b] Count is: 3                         
=> nil   

Thread Singleton

Thread Singleton dependencies are constructed once for any thread or fiber.

class Counter
   attr_reader :count

   def initialize
      @count = 0
   end
   
   def inc
      @count += 1
   end
end

Inoculate.initialize do |config|
   config.thread_singleton(:counter) { Counter.new }
end

class Example
   include Inoculate::Porter
   inoculate_with :counter
   
   def initialize(name)
      @name = "Example: #{name}"
   end
   
   def to_s
      counter.inc
      "[#{@name}] Count is: #{counter.count}"
   end
end

class AnotherExample
   include Inoculate::Porter
   inoculate_with :counter

   def initialize(name)
      @name = "AnotherExample: #{name}"
   end

   def to_s
      5.times { counter.inc }
      "[#{@name}] Count is: #{counter.count}"
   end
end

threads = %w[a b].map do |tag|
   Thread.new(tag) do |t|
      e = Example.new(t)
      a = AnotherExample.new(t)
      puts e, e, a, a
   end
end

threads.each(&:join)

This results in:

[Example: a] Count is: 1
[Example: b] Count is: 1
[Example: b] Count is: 2
[Example: a] Count is: 2
[AnotherExample: b] Count is: 7
[AnotherExample: a] Count is: 7
[AnotherExample: b] Count is: 12
[AnotherExample: a] Count is: 12
=> [#<Thread:0x000000010d703c68 (irb):177 dead>, #<Thread:0x000000010d703b50 (irb):177 dead>]

Renaming the Declaration API

The inoculate_with API is named to avoid immediate collisions with other modules and code you may have. You can use it as-is, or rename it to something you see fit for your project.

require "inoculate"

class HistogramGraph
  include Inoculate::Porter[:inject]
  inject :counter
end

Hide Your Dependency on Inoculate

Writing Inocuate::Porter everywhere in your code is probably going to get old fast, feel free to hide it behind a base class or common included module.

# Make it available to all Rails controllers.
class ApplicationController < ActionController::Base
  include Inoculate::Porter[:dependencies]
end

Installation

Inoculate is a pure ruby library and does not rely on any compiled dependencies.

Install it by adding it to your gemfile and then running bundle install

gem "inoculate"

Or manually install it with gem

$ gem install inoculate

Supported Ruby Versions

Inoculate is tested against the following Ruby versions:

• 2.7
• 3.0
• 3.1
• 3.2-rc

Development

After checking out the repo:

• run bin/setup to install dependencies.
• run rake spec to run the tests.
• run rake spec:all to run the tests across supported Ruby versions using Docker.
• run rake standard to see lint errors.

You can also run bin/console for an interactive prompt that will allow you to experiment.

Local Installation

Run bundle exec rake install or bundle exec rake install:local.

Releasing

• Update the version number in lib/inoculate/version.rb.
• Run bundle exec rake yard to generate the latest documentation.
• Run bundle exec rake release to create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/tinychameleon/inoculate.

License

The gem is available as open source under the terms of the MIT License.