misc: Introduce BaseResult to get rid of OpenStruct

[vincent-pochet]

Context

As a requirement to enable YJIT compiler for Ruby, we need to get rid of OpenStruct as it leads to a huge memory consumption.

At the same time, we are lacking visibility on what properties are attached to result objects returned by services.

Description

This PR introduces a new BaseResult result object, that should be used a a base in every services to define the attributes of a Result:

module SomeModule
  class SomeService < BaseService
    Result = BaseResult[:attr_name1, :attr_name2]

To keep compatibility until all services are migrated to this approach, the BaseService is still relying on a LegacyResult using OpenStruct as a parent class.

[julienbourdeau]

Awesome! Being able to see what's expected in the result will be a tremendous help.

Just thinking out loud about the syntax. How do you feel about using ActiveModel::Attributes?

module AddOns
  class ApplyTaxesService < BaseService
    class Result < BaseResult
      attribute :add_on
      attribute :something, default: true
    end

    def call
      # 
    end
  end
end

def BaseResult
  include ActiveModel::Attributes

  # ...
end

[vincent-pochet]

Awesome! Being able to see what's expected in the result will be a tremendous help.

Just thinking out loud about the syntax. How do you feel about using ActiveModel::Attributes?

module AddOns
  class ApplyTaxesService < BaseService
    class Result < BaseResult
      attribute :add_on
      attribute :something, default: true
    end

    def call
      # 
    end
  end
end

def BaseResult
  include ActiveModel::Attributes

  # ...
end

I like the idea, but I see to problems with that:

1. It leads to a "heavier" definitions, and I would prefer keeping a short syntax (more a matter or personal preference here 🙂 )
2. ActiveModel::Attributes is built for basic, but most of our return objects are model instances or array of model instances, so I'm not sure it would bring much value (+ we have no need for validation as it must be handled at service level)

[julienbourdeau]

🙌 🙌 🙌