pickling fails with mpmath numbers

[fredrik-johansson]

Hello, in order to save large amounts of high-precision data,
I need to serialize mpmath numbers. Unfortunately, this fails with an
exception I don't understand, since the method **getstate** seems to be
defined (see below). Converting to and from strings is only a temporary
option, because it is way too slow and wastes space.

Example:

In [2]:import mpmath

In [3]:a = mpmath.mpc(1+2j)

In [4]:a
Out[4]:mpc(real='1.0', imag='2.0')

In [5]:import pickle

In [6]:pickle.dumps(a)

Results in:

<type 'exceptions.TypeError'>: a class that defines **slots** without
defining **getstate** cannot be pickled What version of the product are you using? On what operating system? Python 2.5
mpmath 0.7
on opensuse 10.2

Original issue for #74: http://code.google.com/p/mpmath/issues/detail?id=34

Original author: https://code.google.com/u/109204080795773808200/

[fredrik-johansson]

This bug has been fixed in svn.

If you don't want to install the svn version, you can make your copy of 0.7 work by
adding the following methods to the mpf class in mptypes.py:

```
def __getstate__(self): return self._mpf_
def __setstate__(self, val): self._mpf_ = val
```

And the following to the mpc class:

```
def __getstate__(self): return self._mpc_
def __setstate__(self, val): self._mpc_ = val
```

Original comment: http://code.google.com/p/mpmath/issues/detail?id=34#c1

Original author: https://code.google.com/u/111502149103757882156/

[fredrik-johansson]

I must correct myself: the **getstate** and **setstate** methods should only be added
to the mpf class.

Original comment: http://code.google.com/p/mpmath/issues/detail?id=34#c2

Original author: https://code.google.com/u/111502149103757882156/

[fredrik-johansson]

Pickling works with SVN version.
This is so cool!
Thanks!

Original comment: http://code.google.com/p/mpmath/issues/detail?id=34#c3

Original author: https://code.google.com/u/109204080795773808200/

[fredrik-johansson]

**Status:** Fixed  

Original comment: http://code.google.com/p/mpmath/issues/detail?id=34#c4

Original author: https://code.google.com/u/111502149103757882156/