Python extension using a C library with one 'hello' function

Jason Swails jason.swails at
Tue Nov 4 17:28:57 CET 2014

On Tue, 2014-11-04 at 21:45 +0630, Veek M wrote:
> Jason Swails wrote:
> > I've submitted a PR to your github repo showing you the changes
> > necessary to get your module working on my computer.
> Segfaults :p which is an improvement :)

What operating system are you running this on?  It works fine for me on

bash$ ls
hello.c  hello.h  pyhello.c
bash$ python3.4 build_ext --inplace
running build_ext
building '_hello' extension
creating build
creating build/temp.linux-x86_64-3.4
x86_64-pc-linux-gnu-gcc -pthread -fPIC -I/usr/include/python3.4 -c pyhello.c -o build/temp.linux-x86_64-3.4/pyhello.o
pyhello.c:15:5: warning: initialization from incompatible pointer type [enabled by default]
     {"hello", py_hello, METH_NOARGS, py_hello_doc},
pyhello.c:15:5: warning: (near initialization for ‘hellomethods[0].ml_meth’) [enabled by default]
x86_64-pc-linux-gnu-gcc -pthread -fPIC -I/usr/include/python3.4 -c hello.c -o build/temp.linux-x86_64-3.4/hello.o
x86_64-pc-linux-gnu-gcc -pthread -shared build/temp.linux-x86_64-3.4/pyhello.o build/temp.linux-x86_64-3.4/hello.o -L/usr/lib64 -lpython3.4 -o /home/swails/BugHunter/CAPI/Python/junk/hello/
bash$ python3.4
Python 3.4.1 (default, Aug 24 2014, 10:04:41) 
[GCC 4.7.4] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import hello
>>> hello.hello()
hello world

You can get rid of the warning by casting py_hello to (PyCFunction)...
maybe that's causing your segfault?

All the best,

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