Topdown

This is a service library. You can use it to create service objects and model simple flows in pipelines. It allows to create services and pipelines programmatically or you can define them in classes by including a module.

Installation

Add this line to your application's Gemfile:

gem 'topdown'

And then execute:

$ bundle

Or install it yourself as:

$ gem install topdown

Usage

Have a look at the test files.

result = Topdown::Service
  .call(a: 0) { context.a = 1 }
result.success?
result.a == 1 # true

result = Topdown::Service
  .create { context.a = 1 }
  .call(a: 0)
result.success?
result.a == 1 # true

result = Topdown::Service
  .create { context.a = 1 }
  .expect(:a)
  .call(a: 0)
result.success?
result.a == 1 # true

result = Topdown::Service
  .create {}
  .expect(:b)
  .call(a: 0)
result.failure? # true

result = Topdown::Service
  .create { raise 'stop' }
  .call
result.failure? # true
result.error.message == 'stop' # true

Topdown::Service
  .call(context) { puts context }

Topdown::Service
  .expect(contract)
  .call(context) { puts context }
  
Topdown::Service
  .expect(contract)
  .call(context) { puts context }
  

Topdown::Pipeline
  .expect(contract)
  .steps(service1, service2)
  .call(context)

Topdown::Pipeline
  .expect(contract)
  .step(service1)
  .step(service2)
  .call(context)

class Flow
  include Topdown::Service
  
  CONTRACT = %i(:a, :b, :c)
  
  expect(CONTRACT)
  
  def call
    puts context  
  end
end

Flow.call(a: 1, b: 2, c: 3)

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

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

License

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