Hrvoje Niksic wrote:
> Calvin Spealman wrote:
>> I don't think it would be unreasonable to consider either 1) making
>> functools.partial picklable (I don't know how feasible this is)
>
> It's not only feasible, but quite easy and, I think, useful. A
> "partial" instance is a simple triplet of (function, args, kwds), and it
> can be pickled as such. For example:
>
> >>> import copy_reg, functools
> >>> def _reconstruct_partial(f, args, kwds):
> ... return functools.partial(f, *args, **(kwds or {}))
> ...
> >>> def _reduce_partial(p):
> ... return _reconstruct_partial, (p.func, p.args, p.keywords)
> ...
> >>> copy_reg.pickle(functools.partial, _reduce_partial)
>
> Test:
>
> >>> import operator, cPickle as cp
> >>> p = functools.partial(operator.add, 3)
> >>> p(10)
> 13
> >>> cp.dumps(p)
>
'c__main__\n_reconstruct_partial\np1\n(coperator\nadd\np2\n(I3\ntp3\nNtRp4\n.'
> >>> p2 = cp.loads(_)
> >>> p2(10)
> 13
>
> Iedally this should be implemented in the functools.partial object itself.
Confirmed:
from multiprocessing import Pool
def power (x, pwr=2):
return x**pwr
import functools
run_test = functools.partial (power, pwr=3)
import copy_reg, functools
def _reconstruct_partial(f, args, kwds):
return functools.partial(f, *args, **(kwds or {}))
def _reduce_partial(p):
return _reconstruct_partial, (p.func, p.args, p.keywords)
copy_reg.pickle(functools.partial, _reduce_partial)
if __name__ == "__main__":
pool = Pool()
cases = [3,4,5]
results = pool.map (run_test, cases)
print results
$python test_multi.py
[27, 64, 125]
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