Function get_category

crates/vm/src/stdlib/_warnings.rs:99–130

Validate and resolve the category argument, matching get_category() in C.

(
        message: &PyObjectRef,
        category: Option<PyObjectRef>,
        vm: &VirtualMachine,
    )

    /// Validate and resolve the category argument, matching get_category() in C.
    fn get_category(
        message: &PyObjectRef,
        category: Option<PyObjectRef>,
        vm: &VirtualMachine,
    ) -> PyResult<Option<PyTypeRef>> {
        let cat_obj = match category {
            Some(c) if !vm.is_none(&c) => c,
            _ => {
                if message.fast_isinstance(vm.ctx.exceptions.warning) {
                    return Ok(Some(message.class().to_owned()));
                } else {
                    return Ok(None); // will default to UserWarning in warn_explicit
                }
            }
        };

        let cat = PyTypeRef::try_from_object(vm, cat_obj.clone()).map_err(|_| {
            vm.new_type_error(format!(
                "category must be a Warning subclass, not '{}'",
                cat_obj.class().name()
            ))
        })?;

        if !cat.fast_issubclass(vm.ctx.exceptions.warning) {
            return Err(vm.new_type_error(format!(
                "category must be a Warning subclass, not '{}'",
                cat.class().name()
            )));
        }

        Ok(Some(cat))
    }

    #[pyfunction]
    fn warn(args: WarnArgs, vm: &VirtualMachine) -> PyResult<()> {