Decorate errors automatically about pragma

[aldesantis]

I wonder whether this could be implemented in the form of response transformers, e.g.

class Pragma::Transformer::CastSymbol < Pragma::Transformer::Base
  def call(options)
    return unless options['result.response'].is_a?(Symbol)
    response_klass = "Pragma::Operation::Response::#{options['result.response'].to_s.camelize}"
    options['result.response'] = response_klass.constantize
  end
end

class Pragma::Transformer::Instantiate < Pragma::Transformer::Base
  def call(options)
    return unless options['result.response'] < Pragma::Operation::Response::Base
    options['result.response'] = options['result.response'].new
  end
end

class Pragma::Transformer::DecorateErrors < Pragma::Transformer::Base
  def call(options)
    return unless options['result.response'].entity.is_a?(Pragma::Error)
    options['result.response'].decorate_with(Pragma::Decorator::Error)
  end
end

Pragma::Operation::Base.transformers << Pragma::Transformer::CastSymbol
Pragma::Operation::Base.transformers << Pragma::Transformer::Instantiate
Pragma::Operation::Base.transformers << Pragma::Transformer::DecorateErrors

Then we could do

options['result.response'] = :not_found

and get the response instantiated and decorated.

I imagine this would be its own gem. In any case, it only makes sense if it would also be used in other places.

My other concern is that this could very easily be abused to add steps to an operation without having to call step. Perhaps we should only allow to manipulate the response and nothing else?