Method try_from_object

crates/vm/src/stdlib/_io.rs:70–91

(vm: &VirtualMachine, obj: PyObjectRef)

impl TryFromObject for Fildes {
    fn try_from_object(vm: &VirtualMachine, obj: PyObjectRef) -> PyResult<Self> {
        use crate::builtins::int;
        let int = match obj.downcast::<int::PyInt>() {
            Ok(i) => i,
            Err(obj) => {
                let fileno_meth = vm.get_attribute_opt(obj, "fileno")?.ok_or_else(|| {
                    vm.new_type_error("argument must be an int, or have a fileno() method.")
                })?;
                fileno_meth
                    .call((), vm)?
                    .downcast()
                    .map_err(|_| vm.new_type_error("fileno() returned a non-integer"))?
            }
        };
        let fd = int.try_to_primitive(vm)?;
        if fd < 0 {
            return Err(vm.new_value_error(format!(
                "file descriptor cannot be a negative integer ({fd})"
            )));
        }
        Ok(Self(fd))
    }
}

#[cfg(unix)]