Python参数注解未解析引用

Question

为什么提示找不到我的类(class)？为什么我应该创建另一个具有相同名称的类以使其不提示？

from typing import Dict


class WeekDay:

    def __init__(self, day_number, day_name):
        self.day_name = day_name
        self.day_number = day_number

    @staticmethod
    def get_week_days() -> Dict[str, WeekDay]:  # WeekDay unresolved reference error
        weekdays = {
            "monday": WeekDay(1, "Monday"),
            "tuesday": WeekDay(2, "Tuesday"),
            "wednesday": WeekDay(3, "Wednesday"),
            "thursday": WeekDay(4, "Thursday"),
            "friday": WeekDay(5, "Friday"),
            "saturday": WeekDay(6, "Saturday"),
            "sunday": WeekDay(7, "Sunday")
        }
        return weekdays

Answer 1

来自文档 ( Section Forward references )

When a type hint contains names that have not been defined yet, that definition may be expressed as a string literal, to be resolved later.

A situation where this occurs commonly is the definition of a container class, where the class being defined occurs in the signature of some of the methods.

所以为了解决这个问题，只需将类型用引号括起来，如下所示:

from typing import Dict


class WeekDay:
    def __init__(self, day_number, day_name):
        self.day_name = day_name
        self.day_number = day_number

    @staticmethod
    def get_week_days() -> Dict[str, 'WeekDay']:  # quote WeekDay 
        weekdays = {
            "monday": WeekDay(1, "Monday"),
            "tuesday": WeekDay(2, "Tuesday"),
            "wednesday": WeekDay(3, "Wednesday"),
            "thursday": WeekDay(4, "Thursday"),
            "friday": WeekDay(5, "Friday"),
            "saturday": WeekDay(6, "Saturday"),
            "sunday": WeekDay(7, "Sunday")
        }

        return weekdays