Dynamic Library causes error when added to setup.py file (on Mac OS.X)

Question

I have a dynamic library, built in cpp that actually works in cpp but is causing much headache when I try to import it from a python class. The error appears simply when I add the lib to my setup.py file. Error:

MacBook-Pro-de-Marcelo-Salloum:python_cpp_interface marcelosalloum$ python userect.py 
Traceback (most recent call last):
  File "userect.py", line 2, in <module>
    from rectangle import Rectangle
ImportError: dlopen(/Users/marcelosalloum/Projects/CppOpenCV/python_cpp_interface/rectangle.so, 2): Symbol not found: __XEatDataWords
  Referenced from: /opt/local/lib/libXext.6.dylib
  Expected in: /opt/local/lib/libX11.6.dylib
 in /opt/local/lib/libXext.6.dylib

Setup.py:

from distutils.core import setup
from distutils.extension import Extension
from Cython.Distutils import build_ext

setup(
    name = 'DyCppInterface',
    version = '1.0',
    author = 'Marcelo Salloum dos Santos',
    # The ext modules interface the cpp code with the python one:
    ext_modules=[
        Extension("rectangle",
            sources=["rectangle.pyx", "cpp_rect.cpp"], # Note, you can link against a c++ library instead of including the source
            include_dirs=[".","source", "/opt/local/include/opencv", "/opt/local/include"],
            language="c++",
            # extra_link_args = ['-arch x86_64'],
            # extra_link_args = ['-arch i386', '-arch x86_64'],
            library_dirs=['/usr/local/lib', 'source'],
            runtime_library_dirs=['/Users/marcelosalloum/Projects/CppOpenCV/python_cpp_interface/source'],
            libraries=['LibCppOpenCV'])
    ],
    cmdclass = {'build_ext': build_ext},
)

It is known that This *.so file uses a c++ OpenCV library. Before adding this lib to my shared library, everything was working perfectly.

• How to figure out what is causing the error?
• Should I try with a static library instead of a dynamic one?
• P.S.: my DYLD_LIBRARY_PATH = ~/Projects/CppOpenCV/python_cpp_interface/source/:/usr/local/mysql/lib/

Answer 1

Thanks to the comments of abarnert, I solved the problem updating and upgrading MacPorts. As abarnert observed, there was a linking problem between /opt/local/lib/libXext.6.dylib and /opt/local/lib/libX11.6.dylib.

So I did:

$ sudo port selfupdate
$ sudo port upgrade outdated