Tomorrow I'll give the details, but yes, you could return a dict from
__getstate__, and then in __setstate__ loop over the dict items and
calling setattr(self, key, value). Perhaps that's enough for you, give
a try!.
On 5/27/08, Eric Jonas <[EMAIL PROTECTED]> wrote:
> _amazing_
>
> Thank you so much.
>
> So one final question regarding additional state in derived classes. To
> simplify I've written a new bit of code for test.py:
>
>
> class MyPairExtra(pair):
> def __init__(self, f=0, s=0):
> self.first = f
> self.second = s
> self.extra = 1234
> self.extra2 = 0
>
>
> p6 = MyPairExtra()
> p6.extra2 = 5678
>
> s6p2 = pkl.dumps(p6, 2)
>
> s6p2load = pkl.loads(s6p2)
> assert s6p2load.extra == 1234
> assert s6p2load.extra2 == 5678
>
> The last assertion currently fails. You'll note that the "extra"
> attribute is correctly recovered by the "extra2" attribute, which we set
> after construction to 5678, is not. Is there any way to pickle arbitrary
> extra object state?
>
> Thanks again,
>
> ...Eric
>
>
>
>
> On Tue, 2008-05-27 at 18:57 -0300, Lisandro Dalcin wrote:
> > Eric, please sorry for the confussion, I just had a bug in __reduce__
> > . Look at the new files attached, your last use case is included in
> > the test script.
> >
> > __reduce__ returns a 3-tuple: the fist item is the type object, with
> > pickle sees as a callable, the second is a tuple argument for that
> > callable, and the third is the state
> >
> > In general, if you implement __reduce__ like this
> >
> > def __reduce__(self):
> > return function, args, state
> >
> > the at un-pickle time, Python (2.5) does
> >
> > function, args, state = unpickle(stream)
> > newobj = function(*args)
> > newobj.__setstate__(state)
> >
> > and then 'newobj' is the final recoverd object.
> >
> > I hope I was clear enough. If you still want to need more complicated
> > stuff, please just keep coming. All this discussion will surelly help
> > in the future at the time Cython tries to implement something to
> > automatically manage all this beast.
> >
> >
> >
> >
> > On 5/27/08, Eric Jonas <[EMAIL PROTECTED]> wrote:
> > > To start with, this is awesome. Thank you so much!
> > >
> > > Next question: What if I want MyPair to have a zero-argument
> > > constructor? (Well, besides self, that is). If I do:
> > >
> > > class MyPair(pair):
> > > def __init__(self):
> > > pass
> > >
> > > then I get "TypeError: ('__init__() takes exactly 1 argument (3 given)".
> > > Does this mean that derived types must always have constructors with the
> > > same number (or more) than their base type?
> > >
> > > Thanks,
> > >
> > > ...Eric
> > >
> > >
> > >
> > >
> > > On Tue, 2008-05-27 at 15:47 -0300, Lisandro Dalcin wrote:
> > > > Well, I admit that the Python docs are a bit hard to follow, but let's
> > > > solve your issue. Look at the attached files,
> > > >
> > > > * mod.pyx: a simple 'cdef' class pair, like the C++ one
> > > > * test.py: a full test, all pickle protocols, includes subclassing
> > > > * cy2py: my lovely distutils based script for the process *.pyx->*.so
> > > > (no need of makefiles, improvements welcome!)
> > > > run like $ python cy2py mod.pyx . This way, you get mod.so.
> > > >
> > > > If you find this code useful, you can donate some dollars ... Just a
> > > > joke! But if you can make it a really good example, It would be great
> > > > to have this included in Cython docs, in order to help other doing
> > > > this, I just do not have the time.
> > > >
> > > > Enjoy!
> > > >
> > > >
> > > > On 5/27/08, Eric Jonas <[EMAIL PROTECTED]> wrote:
> > > > >
> > > > > > But there is definitelly better ways. You sould look at the docs
> of
> > > > > > pickle module, and particularly to the
> __getinitargs__/__getnewargs__
> > > > > > and the __getstate__/__setstate__ stuff. Iff I were to
> implement
> > > > > > pickle protocol, I would explicitely use that.
> > > > >
> > > > >
> > > > >
> > > > > The python pickle docs, which I've been struggling to understand,
> seem
> > > > > to suggest that __reduce__ is necessary for all extensions, or to
> use
> > > > > the copy_reg module. But it seems that __getstate__/__setstate__
> are not
> > > > > applicable for c-extensions. Is this correct?
> > > > >
> > > > > Thanks,
> > > > >
> > > > > ...Eric
> > > > >
> > > > >
> > > > >
> > > > > _______________________________________________
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> > > > > [email protected]
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> > > > >
> > > >
> > > >
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--
Lisandro Dalcín
---------------
Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
PTLC - Güemes 3450, (3000) Santa Fe, Argentina
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