`Quantity[pF]` MVP, via typish (via nptyping NDArrayMeta)

unit_type_check_MVP.py

from dataclasses import dataclass, fields, Field

from typish import SubscriptableType

import yunit


class QuantityMeta(SubscriptableType):
    @property
    def typed_unit(cls):
        return cls.__args__

    def __hash__(cls):
        return hash(cls.typed_unit)

class Quantity(metaclass=QuantityMeta):
    ...

pF = yunit.Unit('pF')
mV = yunit.Unit('mV')

QpF = Quantity[pF]

@dataclass
class Collection:
    k: Quantity[pF]

    def __post_init__(self):
        for field in fields(self):
            field: Field
            value: yunit.Quantity = getattr(self, field.name)
            specified_unit = field.type.typed_unit
            actual_unit = value.display_unit
            assert specified_unit == actual_unit

Collection(k = 8 * mV)