add _partial_ to instantiate api

[jieru-hu]

Closes #1283

add _partial_ support to the instantiation API

[Jasha10]

Many places in this file there is the pattern A == B or partial_equal(A, B).
This could be simplified by moving the A == B part inside of the partial_equal function as below:

Suggested change

	def partial_equal(obj1: Any, obj2: Any) -> bool:
	obj1, obj2 = _convert_type(obj1), _convert_type(obj2)
	def partial_equal(obj1: Any, obj2: Any) -> bool:
	if obj1 == obj2:
	return True
	obj1, obj2 = _convert_type(obj1), _convert_type(obj2)

This would enable simplifying the call-sites of partial_equal.
For example, the expression below on line 30

            if not (obj1[i] == obj2[i] or partial_equal(obj1[i], obj2[i])):
                return False

could then be replaced with this:

            if not partial_equal(obj1[i], obj2[i]):
                return False

[Jasha10]

I've tested out the change locally to make sure it works. If you agree with the idea, I can push a commit to this PR branch!

[jieru-hu]

nice!! feel free to push, thanks jasha!

[Jasha10]

Done in bf689d3

[Jasha10]

Could we get away with bool instead of Optional[bool]?
(Same for the signature of the instantiate_node function below)

[jieru-hu]

the reason it is None is a bit nuanced. with configs like _recursive_,_convert_, a child node will always inherit the parent node config if the config is not specifically set in the child node. But _partial_ is different, i think it only makes sense to set _partial_ per node, which means if _partial_ is not set in a node, it should default to False instead of inherit that from the parent.

[Jasha10]

I agree that _partial_ should be set per-node...
but why not make the default partial=False instead of partial=None?

[jieru-hu]

you are right, Pr updated! :)

[Jasha10]

Removing straggler parentheses from my previous commit:

[Jasha10]

A few more nits:

[Jasha10]

This PR suffers from the same bug as #1669:

>>> instantiate({"_target_": "builtins.dict", "_partial_": True})
functools.partial(<class 'dict'>)
>>> instantiate({"_target_": "builtins.dict", "_partial_": True, "partial": "unrelated"})
Traceback (most recent call last):
...
TypeError: _call_target() got multiple values for argument 'partial'

[Jasha10]

@jieru-hu I think we need a news fragment for this.
Edit: done in #2130.