Return 来自 Python Class 的所有 class 个变量值

Question

我有一个包含所有 AWS 区域的 Python class。我写了一个 class 方法，可以 return 我得到所有地区的列表。有没有更好的方法 returning 所有 class 变量值，这样我就不必像我在下面的示例中那样对 return 语句中的所有值进行硬编码？

class AwsRegion():
    '''
    Class to define AWS Regions
    '''
    OHIO = 'us-east-2'
    NORTH_VIRGINIA = 'us-east-1'
    NORTH_CALIFORNIA = 'us-west-1'
    OREGON = 'us-west-2'
    MUMBAI = 'ap-south-1'
    SEOUL = 'ap-northeast-2'
    SINGAPORE = 'ap-southeast-1'
    SYDNEY = 'ap-southeast-2'
    TOKYO = 'ap-northeast-1'
    FRANKFURT = 'eu-central-1'
    IRELAND = 'eu-west-1'
    LONDON = 'eu-west-2'
    SAO_PAULO = 'sa-east-1'

    @classmethod
    def all(cls, ):
        return [AwsRegion.OHIO, AwsRegion.NORTH_VIRGINIA, AwsRegion.NORTH_CALIFORNIA, AwsRegion.OREGON, \
            AwsRegion.MUMBAI, AwsRegion.SEOUL, AwsRegion.SINGAPORE, AwsRegion.SYDNEY, AwsRegion.TOKYO, \
            AwsRegion.FRANKFURT, AwsRegion.IRELAND, AwsRegion.LONDON, AwsRegion.SAO_PAULO]

Answer 1

在这种情况下，您可以枚举class中所有大写的属性；我将使用 vars() function 访问 class 命名空间：

@classmethod
def all(cls):
    return [value for name, value in vars(cls).items() if name.isupper()]

演示：

>>> class AwsRegion():
...     '''
...     Class to define AWS Regions
...     '''
...     OHIO = 'us-east-2'
...     NORTH_VIRGINIA = 'us-east-1'
...     NORTH_CALIFORNIA = 'us-west-1'
...     OREGON = 'us-west-2'
...     MUMBAI = 'ap-south-1'
...     SEOUL = 'ap-northeast-2'
...     SINGAPORE = 'ap-southeast-1'
...     SYDNEY = 'ap-southeast-2'
...     TOKYO = 'ap-northeast-1'
...     FRANKFURT = 'eu-central-1'
...     IRELAND = 'eu-west-1'
...     LONDON = 'eu-west-2'
...     SAO_PAULO = 'sa-east-1'
...     @classmethod
...     def all(cls):
...         return [value for name, value in vars(cls).items() if name.isupper()]
...
>>> AwsRegion.all()
['us-east-2', 'us-east-1', 'us-west-1', 'us-west-2', 'ap-south-1', 'ap-northeast-2', 'ap-southeast-1', 'ap-southeast-2', 'ap-northeast-1', 'eu-central-1', 'eu-west-1', 'eu-west-2', 'sa-east-1']

Answer 2

作为一般参考，您可以通过以下方式获取任何class的属性。
根据需要选择：

__dict__:

将return所有可写class属性的字典。这通常是您所需要的。

my_obj = MyClass()
attributes = my_obj.__dict__

vars():

与 __dict__ 相同的结果，但使用它被认为是最佳实践。

my_obj = MyClass()
attributes = vars(my_obj)

dir():

Will return 所有 class 属性，包括那些不是由您创建但继承自 object.

my_obj = MyClass()
attributes = dir(my_obj)

对于您的情况，使用 vars() 会很好，正如 Martijn Pieters 在他的中所展示的那样。

Answer 3

看起来您正在做的可能是不小心创建了一个 Enum 类型。

如果您的 AwsRegion class 仅用于存储这些值（而不是许多其他复杂行为），请尝试将其设为 Enum 的子 class。这将为您提供一些不错的方法，而无需您自己重新创建所有方法，并使您的代码对于知道什么是枚举类型的其他人来说更清晰。

from enum import Enum

class AwsRegion2(Enum):
    OHIO = 'us-east-2'
    NORTH_VIRGINIA = 'us-east-1'
    NORTH_CALIFORNIA = 'us-west-1'
    OREGON = 'us-west-2'
    MUMBAI = 'ap-south-1'
    SEOUL = 'ap-northeast-2'
    SINGAPORE = 'ap-southeast-1'
    SYDNEY = 'ap-southeast-2'
    TOKYO = 'ap-northeast-1'
    FRANKFURT = 'eu-central-1'
    IRELAND = 'eu-west-1'
    LONDON = 'eu-west-2'
    SAO_PAULO = 'sa-east-1'


print(list(AwsRegion2))

Answer 4

结合上述答案，我认为这样效率更高：

from enum import Enum

class AwsRegion2(Enum):
    OHIO = 'us-east-2'
    NORTH_VIRGINIA = 'us-east-1'
    NORTH_CALIFORNIA = 'us-west-1'
    OREGON = 'us-west-2'
    MUMBAI = 'ap-south-1'
    SEOUL = 'ap-northeast-2'
    SINGAPORE = 'ap-southeast-1'
    SYDNEY = 'ap-southeast-2'
    TOKYO = 'ap-northeast-1'
    FRANKFURT = 'eu-central-1'
    IRELAND = 'eu-west-1'
    LONDON = 'eu-west-2'
    SAO_PAULO = 'sa-east-1'

    @classmethod
    def all(cls):
        return [variable.value for variable in list(cls)]

print(AwsRegion2.all())

Return 来自 Python Class 的所有 class 个变量值

Return all class variable values from a Python Class

python

class

class-method