Expand

Use Expand to create classes or modules under an existing namespace.

Defining new classes or modules under an existing namespace can be confusing. Using class_eval doesn't work like you think it would.

module SomeGem
  class Thing
  end
end

SomeGem::Thing.class_eval do
  class NewThing
  end
end

# Then try to reference it...
SomeGem::Thing::NewThing #=> warning: toplevel constant NewThing referenced by SomeGem::Thing::NewThing

To make this simpler, you can require expand and specify the namespace and the new class or module.

require 'expand'

Expand.namespace SomeGem::Thing, class: :NewThing do
  # define methods for your class here
end

SomeGem::Thing::NewThing #=> SomeGem::Thing::NewThing

You can also extend an class or object to add the namespace method.

require 'expand'
extend Expand

namespace SomeGem::Thing, class: :NewThing, parent: SomeExistingOtherClass do
  # define methods here
end

namespace SomeGem::Thing, module: :NewModule do
  # define methods here
end

If you want more explicit code or to create multiple modules or classes under a sinngle namespace you can use create_class and create_module

require 'expand'
extend Expand

namespace SomeGem::Thing do
  create_class :NewClass do
    # define methods here
  end

  create_module :NewModule do
    # define methods here
  end
end

Gotchas

Unfortunately, due to the scoping of the blocks passed to the main namespace or expand methods, you are unable to directly reference classes nested in your namespace.

You can, however, pass an argument to the block to use as a reference:

namespace SomeGem::Thing do |klass|
  puts klass #=> yields "SomeGem::Thing"
end

Installation

Add this line to your application's Gemfile:

gem 'expand'

And then execute:

$ bundle

Or install it yourself as:

$ gem install expand

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake test 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/saturnflyer/expand. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

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