I have a requirement of calling third party c functions from inside python. To do this I created a c api which has all the python specific c code ( using METH_VARARGS) to call the third party functions. I linked this code liba.so with the 3 party library libb.so In my python file , I'm doing:
import liba *
Python now complains libb.so not found. What am I doing wrong ?
You have to include liba.so in your PATH, otherwise Python won't know where to look for it.
Try the following code, it'll load the library if it can find it from PATH, otherwise it'll try loading it from the directory of the load script
from ctypes import *
from ctypes.util import find_library
import os
if find_library('a'):
liba = CDLL(find_library('a'))
else:
# library is not in your path, try loading it from the current directory
print 'liba not found in system path, trying to load it from the current directory'
print '%s/%s'%(os.path.dirname(__file__),'liba.so')
liba = CDLL(os.path.join(os.path.dirname(__file__),'liba.so'))
http://docs.python.org/library/ctypes.html#finding-shared-libraries
UPDATE: I was wondering why you created a native library (liba) to access a native 3rd party library (libb). You can import the third party c library straight into python using ctypes and create a python (not native) wrapper for libb. For instance to call the standard c lib time you would do
>>> from ctypes import *
>>> lib_c = CDLL("libc.so.6")
>>> print lib_c.time(None)
1150640792
and for libb
>>> from ctypes import *
>>> lib_b = CDLL("libb")
>>> lib_b.hello_world(None)
CDLL(find_library('b')) it works? Also noticed that you're importing liba slightly strangely, you should either do import liba or from lib import * not import liba * the latter is invalid syntax `