Method try_from_object

crates/vm/src/exceptions.rs:420–436

(vm: &VirtualMachine, obj: PyObjectRef)

impl TryFromObject for ExceptionCtor {
    fn try_from_object(vm: &VirtualMachine, obj: PyObjectRef) -> PyResult<Self> {
        obj.downcast::<PyType>()
            .and_then(|cls| {
                if cls.fast_issubclass(vm.ctx.exceptions.base_exception_type) {
                    Ok(Self::Class(cls))
                } else {
                    Err(cls.into())
                }
            })
            .or_else(|obj| obj.downcast::<PyBaseException>().map(Self::Instance))
            .map_err(|obj| {
                vm.new_type_error(format!(
                    "exceptions must be classes or instances deriving from BaseException, not {}",
                    obj.class().name()
                ))
            })
    }
}

impl ExceptionCtor {