improve object var symantics

[adhami3310]

@benedikt-bartscher made some changes here, let me know if any more is needed

[benedikt-bartscher]

Hi @adhami3310 thanks!
If i read the code correctly, attribute access is still not allowed for bare classes like this one:

class Bare:
  @property
  def prop(self) -> int:
    return 4

@serializer(to=dict)
def serialize_bare(bare: Bare) -> dict[str, int]:
  return {"prop": bare.prop}

I would love to see a fallback to ObjectVar (a bit like #3911). At least if there is a serializer which serializes to dict. Btw, i once tried to add the to= argument to all serializers and determine if smth is an ObjectVar only based on that serializer arg. It just worked fine, all tests passed.
Alternatively we could add a typing stub class like this:

class IsObjectVar: ...

class Bare(IsObjectVar): ...

[adhami3310]

attribute access is still not allowed for bare classes like this one

I believe so, I can add an additional check for has_serializer.

[benedikt-bartscher]

attribute access is still not allowed for bare classes like this one

I believe so, I can add an additional check for has_serializer.

I would suggest limiting this case to serializers which serialize to dict only.
Otherwise, it will be true for this:

class MyCls: ...

@serializer(to=str)
def serialize_my_cls(my_cls: MyCls) -> str:
  return "hi"

Btw, I still think we can narrow this down to serializers and only use the serializers to determine ObjectVar support (dataclasses and rx.Base also have serializers to dict) This will shrink down the checks, make the code cleaner by removing all those cases and potentially even improve performance

[benedikt-bartscher]

Refs:
#3911
#4269
#4268 (maybe we should pick some of the tests from that PR)

[adhami3310]

I would suggest limiting this case to serializers which serialize to dict only.

Should be done!

maybe we should pick some of the tests from that PR

we should, I will try to do that

[benedikt-bartscher]

Thanks, @adhami3310 this looks great! I will test it against our code now

Edit: works great!