Import a cython function: AttributeError: the 'module' object does not have the 'fun' attribute

Question

I wrote a little cython code that

 #t3.pyx from libc.stdlib cimport atoi cdef int fun(char *s): return atoi(s) 

Setup.py setup.py

 from distutils.core import setup from Cython.Build import cythonize setup(ext_modules=cythonize("t3.pyx")) 

I run setup.py with this command

 python setup.py build_ext --inplace 

It gives me

 Compiling t3.pyx because it changed. Cythonizing t3.pyx running build_ext building 't3' extension x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict- prototypes -fno-strict-aliasing -D_FORTIFY_SOURCE=2 -g -fstack-protector- strong -Wformat -Werror=format-security -fPIC -I/usr/include/python2.7 -c t3.c -o build/temp.linux-x86_64-2.7/t3.o t3.c:556:12: warning: '__pyx_f_2t3_fun' defined but not used [-Wunused-function] static int __pyx_f_2t3_fun(char *__pyx_v_s) { ^ x86_64-linux-gnu-gcc -pthread -shared -Wl,-O1 -Wl,-Bsymbolic-functions -Wl,-Bsymbolic-functions -Wl,-z,relro -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -D_FORTIFY_SOURCE=2 -g -fstack-protector-strong -Wformat -Werror=format-security -Wl,-Bsymbolic-functions -Wl,-z,relro -D_FORTIFY_SOURCE=2 -g -fstack-protector-strong -Wformat -Werror=format-security build/temp.linux-x86_64-2.7/t3.o -o /home/debesh/Documents/cython/t3/t3.so 

When I run the python interpreter, it shows me

 >>> import t3 >>> t3.fun('1234') Traceback (most recent call last): File "<stdin>", line 1, in <module> AttributeError: 'module' object has no attribute 'fun' >>> 

Answer 1

The problem is that you defined your method with cdef instead of def . cdef methods can only be called from cython code.

Detailed information can be found in the Python function against the C-functions in the documents.

Python functions are defined using the def statement, as in Python. They take Python objects as parameters and return Python objects.

Functions

C are defined using the new cdef operator. They take either Python objects or C values ​​as parameters and can return either Python objects or C values.

and the important part:

Inside a Cython module, Python functions and C functions can call each other freely, but only Python functions can be called from outside the module interpreted by the Python code. So, any functions that you want to “export” from your Cython module should be declared as Python functions using def.