虽然存在于同一个py文件中但找不到方法-python

Question

我是python新手，我的背景是VB。我收到错误为“NameError：未定义名称'GetASetting'”。

日志：

[INFO              ] Kivy v1.8.0
Purge log fired. Analysing...
Purge 60 log files
Purge finished !
[INFO              ] [Logger      ] Record log in C:\Users\Sudheer\.kivy\logs\kivy_14-07-18_10.txt
[INFO              ] [Factory     ] 157 symbols loaded
[DEBUG             ] [Cache       ] register <kv.lang> with limit=None, timeout=Nones
[DEBUG             ] [Cache       ] register <kv.image> with limit=None, timeout=60s
[DEBUG             ] [Cache       ] register <kv.atlas> with limit=None, timeout=Nones
[INFO              ] [Image       ] Providers: img_tex, img_dds, img_pygame, img_gif (img_pil ignored)
[DEBUG             ] [Cache       ] register <kv.texture> with limit=1000, timeout=60s
[DEBUG             ] [Cache       ] register <kv.shader> with limit=1000, timeout=3600s
 Traceback (most recent call last):
   File "C:\Kivy180\Python33\lib\runpy.py", line 160, in _run_module_as_main
     "__main__", fname, loader, pkg_name)
   File "C:\Kivy180\Python33\lib\runpy.py", line 73, in _run_code
     exec(code, run_globals)
   File "D:\OS Files\workspace\Org\__main__.py", line 7, in <module>
     from formcontrol import FormControl
   File "D:\OS Files\workspace\Org\formcontrol.py", line 8, in <module>
     from login.logincodes import LoginControl
   File "D:\OS Files\workspace\Org\login\logincodes.py", line 7, in <module>
     from dbcodes.logins import LoginAccess
   File "D:\OS Files\workspace\Org\dbcodes\logins.py", line 2, in <module>
     from dbcodes.settings import GetASetting, SettingList
   File "D:\OS Files\workspace\Org\dbcodes\settings.py", line 31, in <module>
     class SettingList(object):
   File "D:\OS Files\workspace\Org\dbcodes\settings.py", line 36, in SettingList
     FirstRun_Get = GetASetting(FirstRun)
 NameError: name 'GetASetting' is not defined

class 和 def 都在同一个 .py 文件中。 代码：

def Initiation():
    from os import path
    print(Getcwd())
    folderpath=str(Getcwd()) 
    fpath = folderpath + "/orgapp.ini"
    dbpath = folderpath + "/orgapp.db"
    if path.exists(fpath)==False:

        #Writing Basic Values
        f = open(fpath,'w')
        setlist=SettingList()
        f.write(setlist.FirstRun+'|True' + '\n')
        f.write(setlist.IniPath+'|'+fpath + '\n')
        f.write(setlist.DBPath+'|'+dbpath + '\n')
        f.close()
        print('File Created')


        #Creating default database
        CreateDB(dbpath)

        return True
    else:
        print('File exists')
        return False

def GetASetting(settingtype):
        if settingtype=='': return None
        path = Getcwd() + '/orgapp.ini'
        f1=open(path,'r')
        for k in f1:
            k=k.replace('\n','')
            c= (k.rsplit(sep='|', maxsplit=2))
            if settingtype.lower() == c[0].lower():
                f1.close()
                if c[1]=='': return None
                else: return c[1]
        f1.close()
        return None

class SettingList(object):
    FirstRun = 'FirstRun'
    IniPath='IniPath'
    DBPath='DBPath'

    FirstRun_Get = GetASetting(FirstRun)
    IniPath_Get = GetASetting(IniPath)
    DBPath_Get = GetASetting(DBPath)



def Getcwd():
    from os import getcwd
    p=''
    p=getcwd()
    p=p.replace('\\', '/')
    return p

def CreateDB(dbpath):
    import sqlite3

    conn = sqlite3.Connection(dbpath, detect_types=sqlite3.PARSE_DECLTYPES|sqlite3.PARSE_COLNAMES)
    conn.execute('''
    create table login
    (loginid text, password text)    
    ''')

    #default user
    id='admin'
    pw='1234'
    conn.execute("insert into login (loginid, password) values (?,?)",(id,pw))


    conn.commit()
    conn.close()

我通过将 def 放在类中进行了解决，但是，上面的代码应该可以工作，请您告诉我我上面犯了什么错误，我检查了名称并且它们是正确的？

Answer 1

GetASetting 需要存在才能使用它。根据您的代码的结构方式，它不会。在类定义之前定义GetASetting。

Answer 2

正如 Ignacio 所说，GetASetting 需要存在才能使用它。确切的原因是：类定义和函数签名（参数的默认值可能包含可执行代码）在 Python 解释器第一次遇到它们时执行——因此，你的函数 GetASetting 需要存在于此时间已经。 （另一方面，这也意味着您也可以在类定义中使用if/else 和其他控制流语句。）

无论如何，如果你不想要这个（而且你通常不想要——由于你遇到的那种不直观的错误），你应该为你的类使用构造函数：

class SettingList(object):
    # All code in here is executed when the interpreter first
    # encounters the class definition
    def __init__(self): # The same applies for this line
        # This code only run when __init__() is actually called.
        self.FirstRun = 'FirstRun'
        self.IniPath='IniPath'
        self.DBPath='DBPath'

        # Now, the function definition below poses no problem.
        self.FirstRun_Get = GetASetting(FirstRun)
        self.IniPath_Get = GetASetting(IniPath)
        self.DBPath_Get = GetASetting(DBPath)

def GetASetting(settingtype):
    # […]
    return None


# usage example
settings = SettingList()
print(settings.FirstRun_Get) 

这在可测试性方面也是一个好主意——现在 SettingList 的每个实例都在创建时进行初始化，这样理论上，您可以模拟文件访问等依赖项，即磁盘上的设置文件。