Change Loader to Type[BaseConstructor] in yaml.add_constructor

[Stannislav]

This fixes a wrong type in the PyYAML stubs.

The last parameter in yaml.add_constructur(tag, constructor, Loader) is the loader class and not its instance. This is consistent with both the PyYAML docs and the way it's implemented in the PyYAML package.

In fact, since the only requirement on the Loader parameter is to have the Loader.add_constructor class method, which is defined in the BaseConstructor base class, we should use the corresponding base class type Type[BaseConstructor]

Simlar types can be added to the similar functions in the same block:

• def add_implicit_resolver(...)
• def add_path_resolver(...)
• def add_constructor(...)
• def add_multi_constructor(...)
• def add_representer(...)
• def add_multi_representer(...)

[JelleZijlstra]

Thank you! Feel free to change the other instances of this issue too.

[Stannislav]

Hi @JelleZijlstra, thanks for having a look. I just added annotations to the other functions mentioned in the description.

It would be good if someone more experience than me in both typing and the yaml-library could glance over it, just to see if all makes sense.

Also, I'm not 100% sure if writing something like Type[Any] in add_path_resolver makes sense.

[Akuli]

We changed all stubs to use the new foo | None syntax instead of Optional[foo] in #5872, and that conflicts with this PR. To fix it, pull from our master and then resolve the conflicts:

$ git pull https://github.com/python/typeshed

Please also use the newer foo | None syntax in this PR.

Also, I'm not 100% sure if writing something like Type[Any] in add_path_resolver makes sense.

It makes sense. PyYAML checks whether it is str or list or some other types.

[Stannislav]

We changed all stubs to use the new foo | None syntax instead of Optional[foo] in #5872, and that conflicts with this PR. To fix it, pull from our master and then resolve the conflicts:

$ git pull https://github.com/python/typeshed

Please also use the newer foo | None syntax in this PR.

Also, I'm not 100% sure if writing something like Type[Any] in add_path_resolver makes sense.

It makes sense. PyYAML checks whether it is str or list or some other types.

Hi @Akuli, thanks for reviewing. Merged master in bc77aed and also addressed your comment in the thread above.

[Akuli]

Thanks!