Python 3.9: TypeError: can't set attributes of built-in/extension type 'type'

[dmrlawson]

Hi,

In Python 3.9 I get the above error when importing capnpy:

$ python
Python 3.9.2 (default, Mar  8 2021, 11:23:50) 
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import capnpy
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/tmp/venv3.9.2/lib/python3.9/site-packages/capnpy/__init__.py", line 4, in <module>
    from capnpy.compiler.compiler import DynamicCompiler
  File "/tmp/venv3.9.2/lib/python3.9/site-packages/capnpy/compiler/compiler.py", line 11, in <module>
    from capnpy import schema
  File "/tmp/venv3.9.2/lib/python3.9/site-packages/capnpy/schema.py", line 7, in <module>
    from capnpy.struct_ import Struct as _Struct
  File "capnpy/struct_.py", line 1, in init capnpy.struct_
  File "capnpy/type.pxd", line 1, in init capnpy.blob
  File "capnpy/type.py", line 33, in init capnpy.type
  File "capnpy/type.py", line 29, in capnpy.type.Types._make
TypeError: can't set attributes of built-in/extension type 'type'
>>>

[antocuni]

Thank you for reporting this. Unfortunately I am no longer working on capnpy, see #53 .
Hopefully someone will step up and look at this issue

[chaosite]

This looks very much like cython/cython#3395, but that issue is not very helpful.

[antocuni]

As described by commit 94939ce, the problem appeared only when using an old version of Cython. With recent cythons, it just works

[chaosite]

I originally got this problem with Cython 0.29.24.

However, I can't reproduce the problem after installing the current version master, so it still seems fixed.