How does `include Dry::AutoInject` works underneath

[L. Papa]

Hi guys,

I was playing around with this library and the related ones and I came up with this line of code: https://github.com/dry-rb/dry-auto_inject/blob/master/lib/dry/auto_inject.rb#L44

Can someone please explain me how this is possible? Since AutoInject::Builder is a class and not a module.

Thank you in advance.

[Peter Solnica]

It is a class but at the end it returns an instance of one of the strategy classes which are module instances. This is based on the module builder pattern that you can read about here: https://dejimata.com/2017/5/20/the-ruby-module-builder-pattern

[L. Papa]

Thanks @solnic for your feedback. I know the module builder pattern. My concern is that AutoInject::Builder is a BasicObject instance. How is it possible to be included in a class?

For instance:

class Some
  include Dry::AutoInject::Builder.new(Dry::Container.new)
end

# => TypeError (wrong argument type Dry::AutoInject::Builder (expected Module))

[Nikita Shilnikov]

@laertispappas it's not Builder included, it's what Builder#[] returns, that is a module

[L. Papa]

@flash-gordon missed it. It is sends #[] message (I had the function call in my mind). Thanks a lot!

[Nikita Shilnikov]

Glad you've figured it out. In the future, please ask questions on the forum, you can find the link in CONTRIBUTING.md (along with other instructions).

[L. Papa]

Sure I will @flash-gordon thank you.