Question

我想隐式关闭类实例销毁的工作簿。 xlsxwriter.workbook.py方法说要明确地执行它然后它工作。但是在每个Excel文件创建脚本结束时，我必须添加额外的行来关闭Workbook。有没有办法让它自动关闭？

import pandas as pd
import xlsxwriter

class ExcelFile():

def __init__(self, file_name):
    self.writer = pd.ExcelWriter(file_name, engine='xlsxwriter')
    self.workbook = self.writer.book

def __del__(self):
    self.workbook.close()
    print('del')

脚本：

e = ExcelFile('test.xlsx')
# e.workbook.close() <--This works but I don't want this line

Answer 1

您无法控制何时调用__del__方法。已有关于SO的__del__的大量信息，您可以搜索它（例如，https://stackoverflow.com/a/1481512/1453822）。

相反，我会使用上下文管理器：

class ExcelFile():
    def __init__(self, file_name):
       self.writer = pd.ExcelWriter(file_name, engine='xlsxwriter')
       self.workbook = self.writer.book    

    def __enter__(self):
       return self

    def __exit__(self, exc_type, exc_val, exc_tb):
       print('exit')
       self.workbook.close()

with ExcelFile('test.xlsx') as e:
    # do whatever with e
    pass

输出将是：

'exit'

承诺在退出__exit__块时调用

with ExcelFile(..)，即使引发了异常：

with ExcelFile('test.xlsx') as e:
    1/0

输出

Traceback (most recent call last):
  File "main.py", line 57, in <module>
    1/0
ZeroDivisionError: division by zero

exit

如何在类析构函数中关闭工作簿？

1 个答案: