C-API proper initialization and deallocation of subclasses

[ptb]

Hello all,

I decided to play around with the C-API and have gotten stuck.  I went through the Shoddy example (https://docs.python.org/3/extending/newtypes.html#subclassing-other-types) in the docs and tried to extend it by adding a method which creates and returns a shoddy instance.  I dug around to find ways to allocate and initialize my shoddy instance and that seems to work well.  However, I get segfaults when I try to delete my instance.  The code is in the gist: https://gist.github.com/pbrady/f2daf50761e458bbe44a

The magic happens in the make_a_shoddy function.

Here's a sample session (Python 3.4.1)

>>> from shoddy import make_a_shoddy()
>>> shd = make_a_shoddy()
tup build
shd allocated
list style allocation successful
Py_SIZE(list) : 5
Py_SIZE(shoddy) : 5
>>> type(shd)
<class 'shoddy.Shoddy'>
>>> shd[:]
[1, 2, 3, 4, 5]
>>> shd.increment()
1
>>> shd.increment()
2
>>> del shd
Segmentation fault (core dumped)

This happens even if I don't set the destructor.  Any ideas on what I am doing wrong?

Thanks,
Peter.