Typed alternatives to building a dict of kwargs

[stephenfin]

I see the following pattern fairly regularly:

kwargs = {}
if foo:
    kwargs['foo'] = foo
if bar:
    kwargs['bar'] = bar
if baz:
    kwargs['baz'] = baz
myfunction(**kwargs)

where foo, bar, and baz are all valid optional kwargs for myfunction. For example: [1], [2], [3].

In virtually all cases, the code is written this way because (a) we want to avoid duplicating/overriding the default defined on the method or (b) the method cares about the difference between "unset" and "null" values which Python doesn't currently have a native way to handle (pending PEP-661 or a similar PEP).

The closest thing to a solution that I've found is to declare a TypedDict but that gets real tedious, real fast and still results in some level of duplication:

class Kwargs(TypedDict):
    foo NotRequired[int|None]
    bar: NotRequired[str|None]
    baz: NotRequired[bool|None]
kwargs: Kwargs = {}
...

I could de-duplicate somewhat using typing.Unpack for the actual method or function signature but that leaves code difficult to read and IMO isn't the intended purpose of that utility.

What I think I want is a way to statically retrieve the type hints for a function/method and use those like so:

kwargs: FunctionKwargs[myfunction] = {}
...

but such a thing doesn't appear to exist, nor do I think it would be possible given e.g. the fact that decorators can "manipulate" arguments.

Would anyone be able to share/point to some best practices around this that allow us to avoid duplicating parameter defaults and/or passing None where that value has semantic meaning?

PS: Apologies if this has been asked before. I'm almost certain it will have been (likely many times) but if so my search-fu has failed me 😞