[Feature Request] Add a _scope_ keyword for instantiation to specify a root module about hydra

[ryan-minato]

I did create a small, simple demo that runs correctly, as this branch

main...minato-ellie:hydra:feature/scope

main.py

import hydra
from omegaconf import DictConfig, OmegaConf
from hydra.utils import instantiate


class A:
    def __init__(self, a1=1, a2="a2"):
        self.a1 = a1
        self.a2 = a2

    def __str__(self):
        return f"A: {self.a1}, {self.a2}"


class B:
    def __init__(self, b1=1, b2="b2"):
        self.b1 = b1
        self.b2 = b2

    def __str__(self):
        return f"B: {self.b1}, {self.b2}"
    
class C:
    def __init__(self, a: A, b: B):
        self.a = a
        self.b = b

    def __str__(self):
        return f"C: {self.a}, {self.b}"
    

@hydra.main(config_path="conf", config_name="config")
def main(cfg):
    c = instantiate(cfg.c)
    print(c)
    print(OmegaConf.to_yaml(cfg))


if __name__ == "__main__":
    main()

config.yaml

c:
  _scope_: "__main__"
  _target_: ".C"
  a:
    _target_: ".A"
    a1: 10
  b:
    _target_: ".B"
    b1: 100

Output

C: A: 10, a2, B: 100, b2
c:
  _scope_: __main__
  _target_: .C
  a:
    _target_: .A
    a1: 10
  b:
    _target_: .B
    b1: 100

[Jasha10]

Interesting. Thanks for the proposal, @minato-ellie.