Feature: Speed up compilation with `finalize!`

[apotonick]

We could avoid having to compile the activity with every invocation of step by "marking" the activity as final in the end, which then could trigger compilation (and much better error handling).

class Create < Trailblazer::Operation(finalize: true)
  step :a
  step :b
end.finalize!

When using an extendable loader such as dry-system (or maybe even zeitwerk supports that?) you could add a "loaded" callback that calls activity_class.finalize! automatically.

[apotonick]

The other option I see would be

class Create < Trailblazer::Operation
  structure do
    step :a
    step :b
  end
end

I don't really like this, though.

[apotonick]

We can save the finalize! if we use zeitwerk's on_load (thanks @solnic): https://github.com/fxn/zeitwerk#the-on_load-callback

[yogeshjain999]

Great idea! step would become a lot faster with this!

Although, I think we should confirm if defining nested operations would still be supported with on_load

# create.rb
class Create < Trb::Op
  class Present < Trb::Op
  end

  step Subprocess(Present)
end

I suppose only on_load("Create") would be called here ? 🤔