[Cython] Auto-pickle progress?

[Sturla Molden]

On 20.09.2012 21:11, Ian Bell wrote:

> Auto-pickling would be tremendously helpful as pickling and unpickling
> is one of the most annoying features of working with threads and
> processes in python.

How should Cython interfere how to pickle a C pointer?

cdef class foobar:
   cdef double *data

A C object can be anything. Cython does not know anything about size, 
offset or strides, or even if it's safe to take a copy.

Example: How to pickle a shared memory buffer? Surely we cannot take a 
copy, because that would defeat the purpose of "shared" memory. And even 
if could take a copy, how many bytes should be copied? Do you think an 
autopickler could have figured this out?

https://github.com/sturlamolden/sharedmem-numpy/blob/master/sharedmem/sharedmemory_sysv.pyx

https://github.com/sturlamolden/sharedmem-numpy/blob/master/sharedmem/sharedmemory_win.pyx

On yes, the code is different on Unix and Windows, something the 
auto-pickler could not possibly know either.

Auto-pickling cdef classes is not doable, IMHO.


And by the way, implementing a __reduce__ method manually is not very 
difficult either.


Sturla Molden