Python擱置錯誤 - 索賠NoneType，但對象*是*有

Question

我剛碰到一個完全奇怪的錯誤。我將選擇的東西保存到一個文件中。其中之一是稱爲Tracker的類的一個版本，並且該副本稱爲跟蹤器。

 file = shelve.open(worldname, 'n') 

     file['Terramap'] = terramap 
     file['Satmap'] = satmap 
     file['Gasmap'] = gasmap 
     file['Planetset'] = planetset 
     file['World'] = minimap 
     file['Picture'] = picturemap          
     file['Worlddata'] = worlddata 
     file['Dimension'] = dimension 
     print "check", len(tracker.families) 
     file['Tracker'] = tracker 
     file['Schedule'] = schedule 
     file['Time'] = time 
     file.close()  

如果我有它的文件之前，只打印從跟蹤的東西，純粹是爲了測試跟蹤器仍然存在，它的確可以檢測跟蹤。但隨後單行後，它出現：

File "C:\Users\Mark\Desktop\Ultima Ratio Regum\URR0-2-1.py", line 17522, in world_menu 
    file['Tracker'] = tracker 
    File "C:\Python27\lib\shelve.py", line 132, in __setitem__ 
    p.dump(value) 
TypeError: expected string or Unicode object, NoneType found 

我只是...難住了。這從來沒有發生過，我不明白這是怎麼回事！任何人都可以對此有所瞭解嗎？我所做的一切都是今天將一些東西添加到跟蹤器中，但跟蹤器只能存儲多達數千個字符串，但僅此而已。但是，如果我在保存開始之前創建了一個新的追蹤器，它可以很好地保存。

編輯：

運行pickle.dumps（跟蹤）顯示：

File "C:\Users\Mark\Desktop\Ultima Ratio Regum\29-12-test.py", line 17515, in world_menu 
    pickle.dumps(tracker) 
    File "C:\Python27\lib\pickle.py", line 1374, in dumps 
    Pickler(file, protocol).dump(obj) 
    File "C:\Python27\lib\pickle.py", line 224, in dump 
    self.save(obj) 
    File "C:\Python27\lib\pickle.py", line 286, in save 
    f(self, obj) # Call unbound method with explicit self 
    File "C:\Python27\lib\pickle.py", line 725, in save_inst 
    save(stuff) 
    File "C:\Python27\lib\pickle.py", line 286, in save 
    f(self, obj) # Call unbound method with explicit self 
    File "C:\Python27\lib\pickle.py", line 649, in save_dict 
    self._batch_setitems(obj.iteritems()) 
    File "C:\Python27\lib\pickle.py", line 663, in _batch_setitems 
    save(v) 
    File "C:\Python27\lib\pickle.py", line 286, in save 
    f(self, obj) # Call unbound method with explicit self 
    File "C:\Python27\lib\pickle.py", line 600, in save_list 
    self._batch_appends(iter(obj)) 
    File "C:\Python27\lib\pickle.py", line 615, in _batch_appends 
    save(x) 
    File "C:\Python27\lib\pickle.py", line 286, in save 
    f(self, obj) # Call unbound method with explicit self 
    File "C:\Python27\lib\pickle.py", line 725, in save_inst 
    save(stuff) 
    File "C:\Python27\lib\pickle.py", line 286, in save 
    f(self, obj) # Call unbound method with explicit self 
    File "C:\Python27\lib\pickle.py", line 649, in save_dict 
    self._batch_setitems(obj.iteritems()) 
    File "C:\Python27\lib\pickle.py", line 663, in _batch_setitems 
    save(v) 
    File "C:\Python27\lib\pickle.py", line 286, in save 
    f(self, obj) # Call unbound method with explicit self 
    File "C:\Python27\lib\pickle.py", line 748, in save_global 
    (obj, module, name)) 
PicklingError: Can't pickle <built-in method capitalize of str object at 0x0A1341C0>: it's not found as __main__.capitalize 

Answer 1

該異常是從cPickle.Pickler.dump的內部到來，但它不會出現在回溯，因爲它在存在的一個編譯的C模塊。要獲得的是什麼錯誤指示，請嘗試手動觸發同樣的事情，但與純Python pickle模塊，而不是編譯的C cPickle模塊：

import pickle 
pickle.dumps(tracker) 

這應該顯示錯誤所在。我的第一個猜測是，您的__reduce_ex__或__reduce__的實現不會返回值。