UnboundLocalError：赋值前引用的局部变量'error'

Question

我已经查看了有关此特定错误的其他问题，但在这些情况下，在该过程中存在一条路径，其中变量从未定义，因此在稍后调用时会失败。 但是在我的程序中，我在try方法之前设置变量，在某些条件下在try方法中更改这些变量，然后if语句稍后调用它们但是失败。 当Python到达if语句并尝试创建变量文本时，它声明变量error和error1未定义（在赋值之前引用）。

err = 0
error = 'No Error Set'
error1 = 'No Error1 Set'
try:
    conn = sqlite3.connect(db_dir)
    for row in conn.execute("select max(date) from eod"):
       mxdate = row
    if mxdate == None:
        pass
    else:
        for row in conn.execute('select date, status from eod where date = ?',(mxdate,)):
            _lst_eod = row
    for row in conn.execute("select * from temp"):
        _crnt_eod = row
    conn.close()
except Exception as error:
    error = str(error)
    err = 1
    logged = 0
    try:
        conn.close()
        time = str(right_datetime())[11:19].replace(':','')
        conn = sqlite3.connect(db_dir)
        conn.execute("insert into error_log (date, user, auth, error, _action) values (?,?,?,?,'Failed to select from eod/temp tables.')",(int(str(_date)+time),cred[0],cred[1],error,))
        conn.commit()
        conn.close()
        logged = 1
    except Exception as error1:
        error1 = str(error1)
if err == 1:
    #An error occured here.
    text = '##Error## An error occured while trying to end the day:\n'+error
    if logged == 0:
        text = text+'\n\nA row was written to the error log.'
    else:
        text = text+'\n\nWrite to Error Log failed due to error:\n'+error1
else:
    ....carry on with the rest of the program.

Answer 1

在Python 3中，在退出except块时，将删除 except SomeException as e:语句分配的变量：

>>> e = "something"
>>> try:
...     1/0
... except ZeroDivisionError as e:
...     print(e)
... 
division by zero
>>> e
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'e' is not defined

你的代码中发生了同样的事情： except Exception as error: except Exception as error1:块在它们退出时删除error和error error1 。