Issue with Pydantic Models

mypy-output.txt

dspy/signatures/mypy_issue.py:35: error: Too many arguments for "Signature"  [call-arg]
dspy/signatures/mypy_issue.py:35: error: Incompatible return value type (got "Signature", expected "type[Signature]")  [return-value]
Found 2 errors in 1 file (checked 1 source file)

mypy_issue.py

import typing
from typing import Union, Type, Optional
import pydantic.fields
from pydantic import BaseModel, Field, create_model
from pydantic.fields import FieldInfo

import dsp
from dspy.signatures.field import InputField, OutputField, new_to_old_field

# I don't love this, but mypy cannot deal with the dynamic lookup of this metaclass - rpg
PydanticMetaClass: typing.TypeAlias = pydantic._internal._model_construction.ModelMetaclass

assert PydanticMetaClass == type(pydantic.BaseModel), \
    "Implementation of Signature MetaClass depends on the internals of Pydantic, which have changed."


class SignatureMeta(PydanticMetaClass):
    pass


class Signature(BaseModel, metaclass=SignatureMeta):
    """"""  # noqa: D419
    pass


# example usages

def ensure_signature(
        signature: Union[str, Type[Signature]], instructions: Optional[str] = None
) -> Type[Signature]:
    if signature is None:
        raise ValueError("Signature argument is mandatory")
    if isinstance(signature, str):
        # FIXME: According to mypy, Signature cannot be called with 2 arguments.
        return Signature(signature, instructions)
    if instructions is not None:
        raise ValueError(
            "Don't specify instructions when initializing with a Signature"
        )
    return signature