pickle

Numpy arrays, being extension types (aka defined using in extensions the C API), declare additional fields outside the scope of the Python interpreter (for example the data attribute, which is a Buffer Structure , as documented in Numpy's array interface . To be able to serialize it, Python 2 used to use the __reduce__ function as part of the pickle protocol, as stated in the doc , and explained here . But, even if __reduce__ still exists in Python 3, the Pickle protocol section (and Pickling and unpickling extension types a fortiori) was removed from the doc, so it is unclear what does what.

I'm struggling to pickle a wrapped function when I use a custom callable class as a wrapper. I have a callable class "Dependee" that keeps track of dependencies for a wrapped function with a member variable "depends_on". I'd like to use a decorator to wrap functions and also be able to pickle the resulting wrapped function. So I define my dependee class. Note the use of functools.update_wrapper. >>> class Dependee: ... ... def __init__(self, func, depends_on=None): ... self.func = func ... self.depends_on = depends_on or [] ... functools.update_wrapper(self, func) ... ... def __call__(self,

(It is possible to directly jump to the question, further down, and to skip the introduction.) There is a common difficulty with pickling Python objects from user-defined classes: # This is program dumper.py import pickle class C(object): pass with open('obj.pickle', 'wb') as f: pickle.dump(C(), f) In fact, trying to get the object back from another program loader.py with # This is program loader.py with open('obj.pickle', 'rb') as f: obj = pickle.load(f) results in AttributeError: 'module' object has no attribute 'C' In fact, the class is pickled by name ("C"), and the loader.py program does

I get the following error when I'm reading my .pkl files on spyder (python 3.6.5): IN: with open(file, "rb") as f: data = pickle.load(f) Traceback (most recent call last): File "<ipython-input-5-d9796b902b88>", line 2, in <module> data = pickle.load(f) AttributeError: Can't get attribute 'Signal' on <module '__main__' from 'C:\\Python36\\lib\\site-packages\\spyder\\utils\\ipython\\start_kernel.py'> The context: My program is made of one file: program.py In the program, a class Signal is defined as well as many functions. A simplified overview of the program is provided below: import numpy as

I'm having trouble pickling a Cython class, but only when it's defined inside a package. This problem was noted previously online , but they didn't state how it was resolved. There are two components here: the Cython pickling using a __reduce__ method and a package error. Cython Pickling Success I'll first show how it works without the package part. This example works correctly. Cython File My Cython file is reudce.pyx : cdef class Foo(object): cdef int n def __init__(self, n): self.n = n def __reduce__(self): return Foo, (self.n,) Setup File This may be compiled with a setup.py : from

Is it possible to pickle (using cPickle) an enum that has been exposed with Boost.Python? I have successfully pickled other objects using the first method described here , but none of that seems to apply for an enum type, and the objects don't seem to be pickleable by default. Not as they are in the module. I am given to understand that this is SUPPOSED to be possible, but the way the enum_ statement works prevents this. You can work around this on the python side. Somewhere (probably in a __init__.py file) do something like this: import yourmodule def isEnumType(o): return isinstance(o, type)