Python 2.7 （Python）搁置+；try：如何搜索一个键并在它不存在时设置它'；t是否存在而没有重复代码？

要永久存储用户工作文件夹，我使用shelve。为了知道用户是否配置了文件夹，我使用了3次类似的代码：

pastaUsuario = os.getenv('HOMEDRIVE') + os.getenv('HOMEPATH')
pastaPrincipal = pastaUsuario + '\\rev'
pastaConfig = pastaPrincipal + '\\config'

config = shelve.open(pastaConfig + '\\config.db')
try:
  pastaIsometricosSpooler = config['pastaIsometricosSpooler']
except Exception:
  config['pastaIsometricoSpooler'] = raw_input('Digite o caminho da pasta de extração do       Spooler: ')
  pastaIsometricosSpooler = config['pastaIsometricosSpooler']
finally:
  config.close()

config = shelve.open(pastaConfig + '\\config.db')  
try:
  ultimoIso = config['ultimoIso']
except Exception:
  config['ultimoIso'] = raw_input('Digite o tag do isométrico a ser revisado: ')
  ultimoIso = config['ultimoIso']
 finally:
  config.close()

config = shelve.open(pastaConfig + '\\config.db')
try:
  ultimaRev = config['ultimaRev']
except Exception:
  config['ultimaRev'] = raw_input('Digite a nova revisão: ')
  ultimaRev = config['ultimaRev']
finally:
  config.close()

如何避免重复几乎相同的代码？ 我尝试使用“for”语句来列出：

config = shelve.open(pastaConfig + '\\config.db')
for x in ['pastaIsometricosSpooler', 'ultimoIso', 'ultimaRev']:
  try:
    x = config[x]
  except Exception:
    config[x] = raw_input()
    x = config[x]
  finally:
    config.close()

但是变量集由于引号而无法工作（例如：'ultimaRev'=config['ultimaRev']）

---

对不起，我的英语不好

最好使用函数，而不是让相同的代码在循环中工作。调整您所拥有的：

def getconfig( x, prompt ):   
  try:
    theconf= config[x]
  except Exception:
    config[x] = raw_input( prompt )
    theconf= config[x]
  return theconf

然后您可以使用它三次：

config = shelve.open(pastaConfig + '\\config.db')
ultimaRev = getconfig( 'ultimaRev', 'Digite a nova revisão: ')
ultimoIso = getconfig( 'ultimoIso', 'Digite o tag do' )
pastaIsometricosSpooler = getconfig('pastaIsometricosSpooler', 'Digite o caminho da' )
config.close()