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I'm trying to pickle a big class and getting
TypeError: can't pickle module objects
despite looking around the web, I can't exactly figure out what this means. and I'm not sure which module object is causing the trouble. is there a way to find the culprit? the stack trace doesn't seem to indicate anything.
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Python comes with a built-in package, known as pickle , that can be used to perform pickling and unpickling operations. Pickling and unpickling in Python is the process that is used to describe the conversion of objects into byte streams and vice versa - serialization and deserialization, using Python's pickle module.
With pickle protocol v1, you cannot pickle open file objects, network connections, or database connections.
PicklingError is used when the process of pickling one or more python objects is not able to proceed. pickle.UnpicklingError. This is exception pickle. UnpicklingError is raised when the process of converting a pickled byte stream into python object hierarchie(s) fails.
A module is a Python object with arbitrarily named attributes that you can bind and reference. The Python code for a module named aname normally resides in a file named aname.py, as covered in Module Loading. In Python, modules are objects (values) and are handled like other objects.
Python's inability to pickle module objects is the real problem. Is there a good reason? I don't think so. Having module objects unpicklable contributes to the frailty of python as a parallel / asynchronous language. If you want to pickle module objects, or almost anything in python, then use dill.
Python 3.2.5 (default, May 19 2013, 14:25:55) [GCC 4.2.1 Compatible Apple Clang 4.1 ((tags/Apple/clang-421.11.66))] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import dill >>> import os >>> dill.dumps(os) b'\x80\x03cdill.dill\n_import_module\nq\x00X\x02\x00\x00\x00osq\x01\x85q\x02Rq\x03.' >>> >>> >>> # and for parlor tricks... >>> class Foo(object): ... x = 100 ... def __call__(self, f): ... def bar(y): ... return f(self.x) + y ... return bar ... >>> @Foo() ... def do_thing(x): ... return x ... >>> do_thing(3) 103 >>> dill.loads(dill.dumps(do_thing))(3) 103 >>> Get dill here: https://github.com/uqfoundation/dill
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