Python上下文管理器恢复变量的值？

class RestoreVariable:
    def __init__(self, var_name, original_value):
        self.var_name = var_name
        self.original_value = original_value

    def __enter__(self):
        # 保存当前变量的值
        self.current_value = globals().get(self.var_name, None)
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        # 恢复变量的原始值
        if self.current_value is not None:
            globals()[self.var_name] = self.current_value
        else:
            del globals()[self.var_name]

# 示例使用
x = 10

with RestoreVariable('x', x):
    x = 20
    print(f"Inside with block: x = {x}")  # 输出: Inside with block: x = 20

print(f"Outside with block: x = {x}")  # 输出: Outside with block: x = 10