How can I reference the type hint for an instance variable on another class?

Question

The OpenAI Python types define a Batch class with a status field:

class Batch(BaseModel):
    id: str

    # ...

    status: Literal[
        "validating", "failed", "in_progress", "finalizing", "completed", "expired", "cancelling", "cancelled"
    ]
    """The current status of the batch."""

I'd like to re-use the Literal[...] type hint from the status field in my own class. Here's an attempt:

from typing import Optional, TypedDict
import openai

class FileStatus(TypedDict):
    filename: str
    sha256: str
    file_id: Optional[str]
    batch_id: Optional[str]
    batch_status: Optional[openai.types.Batch.status]
    #                                         ~~~~~~
    # Variable not allowed in type expression Pylance(reportInvalidTypeForm)

What should I use as the type hint for batch_status? I'd prefer to avoid copy/pasting the Literal[...] expression from the OpenAI API if possible.

Is this along the lines of what you're asking for? stackoverflow.com/q/52838204/25441514 — Anerdw
– Anerdw, Commented Sep 16, 2024 at 21:09
@Anerdw I don't think that will produce a valid type annotation either. — juanpa.arrivillaga
– juanpa.arrivillaga, Commented Sep 16, 2024 at 21:58
unfortunately, if you want this to be useful for static type checkers (mypy and pyright) then you are probably just going to have to copy it. — juanpa.arrivillaga
– juanpa.arrivillaga, Commented Sep 16, 2024 at 21:59
A Literal isn't really a good way to define an enumerated type in the first place. — chepner
– chepner, Commented Sep 17, 2024 at 14:56
@chepner That's coming from the OpenAI library, it's not in my control. And what's the alternative for describing JSON? — danvk
– danvk, Commented Sep 18, 2024 at 18:03

Dat Huynh · Accepted Answer · 2024-09-17 06:44:32Z

0

from typing import Literal, Optional, TypedDict, get_type_hints


class Batch:
    id: str
    status: Literal[
        "validating", "failed", "in_progress", "finalizing", "completed", "expired", "cancelling", "cancelled"
    ]


type_hints = get_type_hints(Batch)
status_type = type_hints['status']


class FileStatus(TypedDict):
    filename: str
    sha256: str
    file_id: Optional[str]
    batch_id: Optional[str]
    batch_status: Optional[status_type]

You can use get_type_hints from typing to get type of attributes from class.

answered Sep 17, 2024 at 6:44

Dat Huynh

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2 Comments

user2357112 Over a year ago

This is considered invalid by static type checkers, though.

danvk Over a year ago

For vscode / pyright, this seems to provide autocomplete in some contexts but not others github.com/danvk/gpt-batch-manager/issues/1

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