qvariant_cast "like" in PyQt5/PySide2

qvariant_cast.py

from typing import overload, Union, Type, TypeVar, Any
from functools import lru_cache

from PyQt5.QtCore import QObject, pyqtProperty as Property


@lru_cache(maxsize=200)
def _converter(type_: Union[type, str]):
    class Obj(QObject):
        __slots__ = ("field",)

        def _set(self, val):
            self.field = val

        def _get(self):
            return self.field

        prop = Property(type_, _get, _set)

    def convert(value):
        inst = Obj()
        inst.field = value
        inst.setProperty('prop', value)
        return inst.property('prop')
    return convert


T = TypeVar("T")

@overload
def qvariant_cast(type_: Type[T], value) -> T: ...
@overload
def qvariant_cast(type_: str, value) -> Any: ...
def qvariant_cast(type_: Union[type, str], value):
    """
    Like :cpp:`T qvariant_cast(const QVariant &value)`

    The full range of QVariant casts is not exposed by PyQt5/PySide therefore
    this method trys to subvert existing apis to achieve functional parity.

    Example
    -------
    >>> qvariant_cast(str, None)
    ''
    >>> qvariant_cast(int, None)
    0
    >>> qvariant_cast(bool, '1')
    True
    >>> qvariant_cast(bool, '0')
    False
    >>> qvariant_cast('QStringList', None)
    []
    >>> qvariant_cast(QBrush, Qt.red).color().name()
    '#ff0000'
    """
    converter = _converter(type_)
    return converter(value)