I am attempting to use forward references in my program and I am failing.
This also does not work with the older way of putting the name of a class
as a string. Here is some sample code:

from __future__ import annotations

from dataclasses import dataclass
from typing import TypeAlias


ColorDef: TypeAlias = RGB | int | str



@dataclass(frozen=True, slots=True)
class RGB(object):

Can anyone suggest how I should fix this without reversing the statement
order?

pass


--
Jonathan Gossage

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 2023-09-03 21:43, Jonathan Gossage via Python-list wrote:

I am attempting to use forward references in my program and I am failing. This also does not work with the older way of putting the name of a class
as a string. Here is some sample code:

from __future__ import annotations

from dataclasses import dataclass
from typing import TypeAlias

ColorDef: TypeAlias = RGB | int | str

@dataclass(frozen=True, slots=True)
class RGB(object):

Can anyone suggest how I should fix this without reversing the statement order?

pass

The usual way to deal with forward type references is to use a string
literal, i.e. 'RGB', but that doesn't work with '|', so use typing.Union instead:

from typing import TypeAlias, Union

ColorDef: TypeAlias = Union['RGB', int, str]

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)