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[Python-ideas] Make MappingProxyType picklable

Yury Selivanov yselivanov.ml at gmail.com
Sat Feb 22 04:26:43 CET 2014 
Antony,

On 2/21/2014, 9:13 PM, Antony Lee wrote:
> Currently, mappingproxies are not picklable, which (among other things)
> lead to signature objects being non picklable.  Could this be easily fixed,
> or is there a stronger reason for not allowing that pickling?
> If mappingproxies cannot be made picklable, perhaps signatures can
> implement __getnewargs__ to allow pickling?
> Antony
>
Good catch. I think we'll make Signatures picklable in 3.5
(http://bugs.python.org/issue20726)  It can be implemented
using __reduce__ and __setstate__ methods. We can't use
__getnewargs__ as we have keyword-only arguments in
Parameter and Signature classes (but maybe we'll be able
to use __getnewargs_ex__ in 3.5)

Do you have any other reasons to make mappingproxies
picklable?

Yury
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