In order to take advantage of the strength of both languages, developers use Python bindings which allows them to call C/C++ libraries from python.
Now, the question arises that why there is a need for doing this?
- As we know that, C has faster execution speed and to overcome the limitation of Global Interpreter Lock(GIL) in python, python bindings are helpful.
- We have a large, stable and tested library in C/C++, which will be advantageous to use.
- For performing large scale testing of the systems using Python test tools.
Let’s see the C code which we want to execute with Python :
C++
#include <iostream> class Geek{ public : void myFunction(){ std::cout << "Hello Geek!!!" << std::endl; } }; int main() { // Creating an object Geek t; // Calling function t.myFunction(); return 0; } |
We have to provide those cpp declarations as extern “C” because ctypes can only interact with C functions.
C++
extern "C" { Geek* Geek_new(){ return new Geek(); } void Geek_myFunction(Geek* geek){ geek -> myFunction(); } } |
Now, compile this code to the shared library :
Finally, write the python wrapper:
Python3
# import the module from ctypes import cdll # load the library lib = cdll.LoadLibrary( './libgeek.so' ) # create a Geek class class Geek( object ): # constructor def __init__( self ): # attribute self .obj = lib.Geek_new() # define method def myFunction( self ): lib.Geek_myFunction( self .obj) # create a Geek class object f = Geek() # object method calling f.myFunction() |
Output :
Hello Geek!!!
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