get list of required variables from a forcing source

[RolfHut]

It would be nice to be able to get the list of variables that a forcing source needs to succesfully be able to generate a forcing object. I'm thinking something like:

forcing['genericLumped'].get_variables()

would return a list: ["tas","pr"]

[BSchilperoort]

We can add this as the following:

    @classmethod
    def get_input_variables(
        cls: type["DefaultForcing"],
    ) -> tuple[str, ...] | None:
        return ("pr", "tas", "rsds")  # for example

• tuple is immutable: better for returning here.
• UserForcings have "variables" as input argument, so we cannot know which ones are required based on the class definition. Therefore the possibility of the method returning None.

[RolfHut]

I like that. Should we add that as a template in the central repos and implement it in the model repos?

[BSchilperoort]

I like that. Should we add that as a template in the central repos and implement it in the model repos?

I'll add it as an abstractmethod to the base forcing class, which will force plugin maintainers (i.e. us) to implement it for any implementations of the forcing.