Python3.6 运行提示 ImportError: cannot import name 'CONFIG_FILE'

如下代码：

import os

from utils.file_reader import YamlReader

BASE_PATH = os.path.split(os.path.dirname(os.path.abspath(__file__)))[0]
CONFIG_FILE = os.path.join(BASE_PATH, 'config', 'config.yml')
DATA_PATH = os.path.join(BASE_PATH, 'data')
DRIVER_PATH = os.path.join(BASE_PATH, 'drivers')
LOG_PATH = os.path.join(BASE_PATH, 'log')
REPORT_PATH = os.path.join(BASE_PATH, 'report')

class Config:
    def __init__(self, config = CONFIG_FILE):
        self.config = YamlReader(config).data

    def get(self, element, index=0):
        return self.config[index].get(element)

#coding = UTF-8

import os
import yaml
from xlrd import open_workbook

from config.configg import CONFIG_FILE

class YamlReader:
    def __init__(self, yamlf):
        if os.path.exists(yamlf):    # 判断文件是否存在，如果文件不存在，则提示文件不存在并退出
            self.yamlf = yamlf
        else:
            raise FileNotFoundError('文件不存在')
        self._data = None

    @property
    def data(self):
        # _data只能在本类中调用
        # 如果是第一次调用data，读取yaml文档，否则直接返回之前保存的数据
        if not self._data:
            with open(self.yamlf, 'rb') as f:
                self._data = list(yaml.safe_load_all(f))  # load后是个generator，用list组织成列表
        return self._data

class SheetTypeError(Exception):
    pass

class ExcelReader:
    """
       读取excel文件中的内容。返回list。

       如：
       excel中内容为：
       | A  | B  | C  |
       | A1 | B1 | C1 |
       | A2 | B2 | C2 |

       如果 print(ExcelReader(excel, title_line=True).data)，输出结果：
       [{A: A1, B: B1, C:C1}, {A:A2, B:B2, C:C2}]

       如果 print(ExcelReader(excel, title_line=False).data)，输出结果：
       [[A,B,C], [A1,B1,C1], [A2,B2,C2]]

       可以指定sheet，通过index或者name：
       ExcelReader(excel, sheet=2)
       ExcelReader(excel, sheet='BaiDuTest')
    """
    def __init__(self, excel, sheet=0, title_line=True):
        if os.path.exists(excel):
            self.excel = excel
        else:
            raise FileNotFoundError('excel文件不存在！')
        self.sheet = sheet
        self.title_line = title_line
        self._data = list()

    @property
    def data(self):
        if not self._data:
            workbook = open_workbook(self.excel)
            if type(self.sheet) not in [int, str]:
                raise SheetTypeError('Please pass in <type int> or <type str>, not {0}'.format(type(self.sheet)))
            elif type(self.sheet) == int:
                s = workbook.sheet_by_index(self.sheet)

            if self.title_line:
                title = s.row_values(0)  # 首行为title
                for col in range(1, s.nrows):
                    # 依次遍历其余行，与首行组成dict，拼到self._data中
                    self._data.append(dict(zip(title, s.row_values(col))))
            else:
                for col in range(0, s.nrows):
                    # 遍历所有行，拼到self._data中
                    self._data.append(s.row_values(col))
        return self._data

if __name__ == '__main__':
    y = CONFIG_FILE
    reader = YamlReader(y)
    print(reader.data)
    def __init__(self, excel, sheet=0, title_line=True):
        if os.path.exists(excel):
            self.excel = excel
        else:
            raise FileNotFoundError('excel文件不存在！')
        self.sheet = sheet
        self.title_line = title_line
        self._data = list()

    @property
    def data(self):
        if not self._data:
            workbook = open_workbook(self.excel)
            if type(self.sheet) not in [int, str]:
                raise SheetTypeError('Please pass in <type int> or <type str>, not {0}'.format(type(self.sheet)))
            elif type(self.sheet) == int:
                s = workbook.sheet_by_index(self.sheet)

            if self.title_line:
                title = s.row_values(0)  # 首行为title
                for col in range(1, s.nrows):
                    # 依次遍历其余行，与首行组成dict，拼到self._data中
                    self._data.append(dict(zip(title, s.row_values(col))))
            else:
                for col in range(0, s.nrows):
                    # 遍历所有行，拼到self._data中
                    self._data.append(s.row_values(col))
        return self._data

if __name__ == '__main__':
    y = CONFIG_FILE
    reader = YamlReader(y)
    print(reader.data)

第二段代码运行时提示ImportError: cannot import name 'CONFIG_FILE'

在网上查了不少资料，最终确定是因为循环导入的原因，只要推迟进口就解决了，第二段代码修改如下：

#coding = UTF-8

import os
import yaml
from xlrd import open_workbook

class YamlReader:
 ... ...

if __name__ == '__main__':
    from config.configg import CONFIG_FILE     # 由最上面导入挪到此处就可以了
    y = CONFIG_FILE
    reader = YamlReader(y)
    print(reader.data)

参考资料：https://stackoverflow.com/questions/1556387/circular-import-dependency-in-python

代码参考：http://blog.csdn.net/huilan_same/article/details/76572466