我正在尝试将存储在字典中的类对象莳萝，但由于某种原因我无法做到这一点。
local_env = {}
global_env = {}
exec(x, global_env, local_env)
dill.dumps(local_env['Human'])
为了明确起见，x是一个字符串，它是普通/简单的类定义，而“ Human”是该类的名称。运行上面的代码时，出现以下错误。
------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
/usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/lib/python3.5/pickle.py in _getattribute(obj, name)
267 parent = obj
--> 268 obj = getattr(obj, subpath)
269 except AttributeError:
AttributeError: module 'builtins' has no attribute 'Human'
During handling of the above exception, another exception occurred:
AttributeError Traceback (most recent call last)
/usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/lib/python3.5/pickle.py in save_global(self, obj, name)
906 module = sys.modules[module_name]
--> 907 obj2, parent = _getattribute(module, name)
908 except (ImportError, KeyError, AttributeError):
/usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/lib/python3.5/pickle.py in _getattribute(obj, name)
270 raise AttributeError("Can't get attribute {!r} on {!r}"
--> 271 .format(name, obj))
272 return obj, parent
AttributeError: Can't get attribute 'Human' on <module 'builtins' (built-in)>
During handling of the above exception, another exception occurred:
PicklingError Traceback (most recent call last)
<ipython-input-27-6ce5592364a6> in <module>()
----> 1 dill.dumps(local_env['Human'])
/usr/local/lib/python3.5/site-packages/dill/dill.py in dumps(obj, protocol, byref, fmode, recurse)
241 """pickle an object to a string"""
242 file = StringIO()
--> 243 dump(obj, file, protocol, byref, fmode, recurse)#, strictio)
244 return file.getvalue()
245
/usr/local/lib/python3.5/site-packages/dill/dill.py in dump(obj, file, protocol, byref, fmode, recurse)
234 return
235 # end hack
--> 236 pik.dump(obj)
237 stack.clear() # clear record of 'recursion-sensitive' pickled objects
238 return
/usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/lib/python3.5/pickle.py in dump(self, obj)
406 if self.proto >= 4:
407 self.framer.start_framing()
--> 408 self.save(obj)
409 self.write(STOP)
410 self.framer.end_framing()
/usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/lib/python3.5/pickle.py in save(self, obj, save_persistent_id)
473 f = self.dispatch.get(t)
474 if f is not None:
--> 475 f(self, obj) # Call unbound method with explicit self
476 return
477
/usr/local/lib/python3.5/site-packages/dill/dill.py in save_type(pickler, obj)
1229 #print ("%s\n%s" % (type(obj), obj.__name__))
1230 #print ("%s\n%s" % (obj.__bases__, obj.__dict__))
-> 1231 StockPickler.save_global(pickler, obj)
1232 log.info("# T4")
1233 return
/usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/lib/python3.5/pickle.py in save_global(self, obj, name)
909 raise PicklingError(
910 "Can't pickle %r: it's not found as %s.%s" %
--> 911 (obj, module_name, name))
912 else:
913 if obj2 is not obj:
PicklingError: Can't pickle <class 'Human'>: it's not found as builtins.Human
最佳答案
我是dill作者。简短的答案是它不起作用，因为dill不知道如何操作。
>>> import dill
>>> local_env = {}
>>> global_env = {}
>>> x = "class Human(object):\n pass"
>>> exec(x, global_env, local_env)
>>> local_env
{'Human': <class 'Human'>}
>>> dill.dumps(local_env['Human'])
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/mmckerns/lib/python2.7/site-packages/dill-0.2.5.dev0-py2.7.egg/dill/dill.py", line 243, in dumps
dump(obj, file, protocol, byref, fmode, recurse)#, strictio)
File "/Users/mmckerns/lib/python2.7/site-packages/dill-0.2.5.dev0-py2.7.egg/dill/dill.py", line 236, in dump
pik.dump(obj)
File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/pickle.py", line 224, in dump
self.save(obj)
File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/pickle.py", line 286, in save
f(self, obj) # Call unbound method with explicit self
File "/Users/mmckerns/lib/python2.7/site-packages/dill-0.2.5.dev0-py2.7.egg/dill/dill.py", line 1231, in save_type
StockPickler.save_global(pickler, obj)
File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/pickle.py", line 754, in save_global
(obj, module, name))
pickle.PicklingError: Can't pickle <class 'Human'>: it's not found as __builtin__.Human
更长的答案是
pickle只能序列化在文件内部定义的类，而不能在解释器中或更通常在__main__中序列化。但是，dill通常可以腌制这些动态构建的类，因为它将__main__视为文件，并解析python的内置缓冲区以获取类定义（除其他外）。将类定义隐藏在字符串中，然后使用exec生成类……好吧，这是dill尚无法处理的情况。出于相同的原因，dill也不能使exec内部定义的函数失效。但是，这两个都是有效的情况。已经有功能票（https://github.com/uqfoundation/dill/issues/145）…，因此我将在票上添加指向该问题的链接。