python - 装饰器工厂参数是静态值而不是变量值

Question

所以我有

# my decorator factory
def execute_in(directory):  # <-- I want this to be a variable's value which can change
    def decorator(function):
        def wrapper(*args, **kwargs):
            os.chdir(directory)
            print(directory)  # currently is printing None which is my problem
            value = function(*args, **kwargs)
            os.chdir(home_dir)
            return value
        return wrapper
    return decorator

和

# a function that runs after assigning General.archive_dir a value
@execute_in(General.archive_dir)
def get_data():
  print(General.archive_dir)  # will print the correct directory name
  with open('data.csv', 'r') as f:
      rows = [row for row in csv.reader(f, delimiter=',')]
  return rows

我的问题是，装饰器工厂正在使用程序启动时实例化的变量 General.archive_dir 的值，当时它的值为 None。我希望它在调用修饰函数时使用 General.archive_dir 的值。我该怎么做？

如果这个问题不清楚，我深表歉意。如果可以，请告诉我如何在需要时进行澄清。

Answer 1

一种解决方案是使用 lambda 调用 @execute_in。

wrapper 内的

directory 将成为一个函数，在调用时返回当前值。

archive_dir = None

# decorator factory
def execute_in(directory_path_getter):
    def decorator(function):
        def wrapper(*args, **kwargs):
            print('from wrapper:', directory_path_getter())  # Notice the function call
            value = function(*args, **kwargs)
            return value
        return wrapper
    return decorator

@execute_in(lambda: archive_dir)
def get_data():
    ...

archive_dir = 'some directory'

print(get_data())

打印:

from wrapper: some directory
from get_data: some directory
['some data']