Recursive Object Creation [Feature Request]

[sebascuri]

🚀 Feature Request

It is useful to have a recursive object initialization.

Motivation

Suppose I have the following structure

├ ── conf
|   └── config.yaml
│   └── agent
|        └── agent.yaml
|        └── complex_property
|               └── complex_property_1.yaml
|               └── complex_property_2.yaml
|          
└── my_app.py

The class Agent is defined as follows

class Agent(object):
    def __init__(self, name: str, complex_property: ComplexProperty, seed: int = 0) -> None:
         self.name = name
         self.complex_property = complex_property
         self.seed = seed 

The class ComplexProperty is defined as follows

class ComplexProperty(object):
    def __init__(self, code_number: int, seed: int = 0) -> None:
        self.code_number = code_number
        self.seed = seed

The agent.yaml looks like:

agent:
   class: path_to_agent.Agent
   params:
       name: great_agent
       seed: 0 
       complex_property:
              class: path_to_complex_property.ComplexProperty
              params: 
                   code_number: 1
                   seed: 0

Pitch

Describe the solution you'd like
I'd like to be able to call hydra.utils.instantiate(cfg.agent) and this should recursively initialize the parameters.

I'd also like to be able to default one of the complex_property and be able to override them from the CLI.

I'd also like to be able to default a complex_property that is not necessarily in a sub-directory (by giving a relative path to the .yaml file for instance).

Describe alternatives you've considered
I just initialized the complex_property with hydra.utils.instantiate and then within python initialize the agent.

[sebascuri]

It is also useful to set a global parameter (in this case the seed) in the config.yaml, such that if you modify it from the CLI, you modify it in all the configs, too.

[omry]

Please see #566. It is an RFC (Request for comments) for a possible approach.

[omry]

It is also useful to set a global parameter (in this case the seed) in the config.yaml, such that if you modify it from the CLI, you modify it in all the configs, too.

See interpolations in the OmegaConf documentation.