Are the type stubs for `decorator` accurate?

[MarcoGorelli]

If I write:

from decorator import FunctionMaker

fm = FunctionMaker(lambda x: x)
print(f'{fm.defaults=}')

then I see

fm.defaults=None

However, the stubs show:

typeshed/stubs/decorator/decorator.pyi

Line 23 in ecd5141

defaults: tuple[Any, ...]

and None can't be assigned to tuple[Any, ...]

@donBarbos sorry for the ping, I just saw that you worked on these stubs a few months ago. Can you tell if it's accurate that defaults should be tuple[Any, ...] | None?

The inspect docs also note:

defaults is an n-tuple of default argument values corresponding to the last n positional parameters, or None if there are no such defaults defined

[donBarbos]

sorry, my bad.
judging by source code I decided that the fields are set only if they are not None:
https://github.com/micheles/decorator/blob/143887ed562e83007271df94527eb8f4c269ed4c/src/decorator.py#L100-L111

        if name:
            self.name = name
        if signature is not None:
            self.signature = signature
        if defaults:
            self.defaults = defaults
        if doc:
            self.doc = doc
        if module:
            self.module = module
        if funcdict:
            self.dict = funcdict

so maybe for other arguments (which become fields) this also applies.
would you like to send PR? (or I can also send PR)

[MarcoGorelli]

thanks!

i find the logic a bit surprising - these fields are initialised to an empty tuple, which then may get overwritten. so technically they can also be tuples

In [1]: from decorator import FunctionMaker

In [2]: type(FunctionMaker.args)
Out[2]: tuple

do you think a fix should be to

• change the defaults in decorator itself, something like

  args = []
  vargs = None
  varkw = None
  defaults = None
  kwonlyargs = []
  kwonlydefaults = {}

• modify the stubs to also include tuple[Any, ...] in the type stubs for each of these variables, as possibly some missing None? e.g.

  - args: list[str]
  + args: list[str] | tuple[str, ...]

• modify the stubs to use less strict annotations, like args: Sequence[str]
  ?

[donBarbos]

I would prefer to list all the possible types for each of the fields, firstly because there are not so many of them, and secondly, each of them has its own possible types.

but before, yea, it's better to get rid of the default tuple in source code

[MarcoGorelli]

Sure, thanks - I've started by opening a PR to them here: micheles/decorator#174