Hi, I was reading about Odoo Guidelines, expecially this: 

• In a Model attribute order should be

  1. Private attributes (_name, _description, _inherit, …)

  2. Default method and _default_get

  3. Field declarations

  4. Compute, inverse and search methods in the same order as field declaration

  5. Selection method (methods used to return computed values for selection fields)

  6. Constrains methods (@api.constrains) and onchange methods (@api.onchange)

  7. CRUD methods (ORM overrides)

  8. Action methods

  9. And finally, other business methods.

I see that in 'sale' addon within sale_order.py (sale.py in Odoo14 and previous version), @api.depends like amount_all, get_invoiced, get_invoiced_status and many others have been declared BEFORE field declaration.

Since I'm extending sale order model for my company and I also re-defined _amount_all() method, I was wondering if there is a specific reason behind this choice. 

Thanks, and have a good day !