I didn't manage to get it to work to do def load_instrument(filename:str, paths_stack:list=None) -> Instrument: because adding from pyaml.instrument import Instrument caused circular imports of the factory module. Maybe someone has a suggestion for how to get around that?

For your circular import, it is caused (from what I understand) by wanting to specify the type (Instrument). In some packages, like numpy, there's a special typing module to avoid this.

Yes, since type checking is everywhere else I think it should be here too since it's best practice to do it. I tried to use TYPE_CHECKING from typing and also annotations from __future__ in case it was a problem related to Python 3.10 but none of the combinations I tried worked. But could also be that I need to add it at many more places than I tried since it seems like the factory module is imported in several other modules that are imported by Instrument. I ran into problems in at least controlsystem.py and cfm_magnet.py but could be more places.

Personally, i would really prefer to be able to write:

from pyaml.instrument import Instrument
sr = Instrument.load("tests/config/sr.yaml")
print(sr)

It uses a static class method and is much more in an object oriented style and last but not least you hide this paths_stack internal parameters.

class Instrument(object):    
    """PyAML top level class"""

    @staticmethod
    def load(filename:str) -> "Instrument":
        return load_instrument(filename)
...

The above works perfectly in vscode and provides completion.

For solving this kind of circular import you can:
But you still need to use type annotation as str.

from typing import Union, TYPE_CHECKING

if TYPE_CHECKING:
    from pyaml.instrument import Instrument

def load_instrument(filename:str, paths_stack:list=None) -> "Instrument":

For solving this kind of circular import you can: But you still need to use type annotation as str.

from typing import Union, TYPE_CHECKING

if TYPE_CHECKING:
    from pyaml.instrument import Instrument

def load_instrument(filename:str, paths_stack:list=None) -> "Instrument":

I will try it. Maybe I was then just missing the quotation marks for it to work.

I have added the suggestions from @JeanLucPons. I will now rewrite the tests and then set it ready for review so you can review if it should be merged or not.

Personally I have no objection to merge this PR. As it will break backward compatibility with the frontend, the release number will be increased following #36. So if you want to rename Instrument to Accelerator and if nodoby has objection, please proceed.
doc and jupyter code from @simoneliuzzo will also have to be updated.

Also for me the single instrument (or Accelerator, ok for me as well) per yaml config file is also ok. I can help if needed, let me know @TeresiaOlsson

Okay, then I will also add the changes to change the name from Instrument to Accelerator. My plan was to put that in another PR but then I will add it to this too.

I have fixed the tests now and made it ready for review.