問題描述

我曾嘗試使用 sip 包裝器類型的 abc.ABCMeta，它在使用 abc.ABC 進行子類化時效果很好.

I had tried the abc.ABCMeta with sip wrapper type, and it works well when subclass with abc.ABC.

class QABCMeta(wrappertype, ABCMeta):
    pass

class WidgetBase(QWidget, metaclass=QABCMeta):
    ...

class InterfaceWidget(WidgetBase, ABC):
    ...

class MainWidget(InterfaceWidget):
    ...

但它不適用于 typing.Generic.

class QGenericMeta(wrappertype, GenericMeta):
    pass

class WidgetBase(QWidget, Generic[T], metaclass=QGenericMeta):
    ...

class GenericWidget(WidgetBase[float]):
    ...

它提出了:

line 980, in __new__
    self if not origin else origin._gorg)
TypeError: can't apply this __setattr__ to sip.wrappertype object

我希望它像往常一樣使用通用子類:

I expected it to use generic subclass as usual:

class TableBase(QTableWidget, Generic[T]):
    @abstractmethod
    def raw_item(self, row: int) -> T:
        ...
    def data(self) -> Iterator[T]:
        yield from (self.raw_item(row) for row in range(self.rowCount()))

class MainTable(TableBase[float]):
    def raw_item(self, row: int) -> float:
        return float(self.item(row, 1).text())  # implementation

table = MainTable()
for data in table.data():
    data: float

但是在沒有繼承Generic[T]的情況下，data仍然是Any.

But the data is still Any when without inherit Generic[T].

可以用 PEP 560 解決類型檢查嗎?

Can it solved with PEP 560 to do type checking?

推薦答案

嗯，我找到了答案.

由于typing.Generic的元類是abc.ABC，它也應該基于abc.ABCMeta.但這僅適用于 Python 3.7 或更高版本.

Since the metaclass of typing.Generic is abc.ABC, it should based on abc.ABCMeta too. But this is only works with Python 3.7 or above.

然后，只需使用 type(QObject) 而不是 sip.wrappertype:

And then, just use type(QObject) instead of sip.wrappertype:

# -*- coding: utf-8 -*-

from abc import abstractmethod, ABC, ABCMeta
from typing import TypeVar, Generic, Iterator
from PyQt5.QtCore import QObject
from PyQt5.QtWidgets import QTableWidget

QObjectType = type(QObject)
T = TypeVar('T')


class QABCMeta(QObjectType, ABCMeta):
    pass


class BaseWidget(QTableWidget, Generic[T], metaclass=QABCMeta):

    @abstractmethod
    def raw_item(self, row: int) -> T:
        ...

    def data(self) -> Iterator[T]:
        yield from (self.raw_item(row) for row in range(self.rowCount()))


class TestWidget(BaseWidget[float], ABC):  # optional inherit ABC.

    def raw_item(self, row: int) -> float:
        return float(self.item(row, 1).text())


if __name__ == '__main__':
    w = TestWidget()
    for f in w.data():
        pass

此代碼適用于PyCharm IDE，變量f的注解為float.

This code is works for PyCharm IDE, the annotation of variable f is float.

把PyQt5改成PySide2也可以！

這篇關于如何在沒有元類沖突的情況下將泛型類型與 PyQt 子類一起使用?的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！