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pythonobjective-cpyobjc

Is it possible to call a Python module from ObjC?


Using PyObjC, is it possible to import a Python module, call a function and get the result as (say) a NSString?

For example, doing the equivalent of the following Python code:

import mymodule
result = mymodule.mymethod()

..in pseudo-ObjC:

PyModule *mypymod = [PyImport module:@"mymodule"];
NSString *result = [[mypymod getattr:"mymethod"] call:@"mymethod"];

Solution

  • As mentioned in Alex Martelli's answer (although the link in the mailing-list message was broken, it should be https://docs.python.org/extending/embedding.html#pure-embedding).. The C way of calling..

    print urllib.urlopen("http://google.com").read()
    
    • Add the Python.framework to your project (Right click External Frameworks.., Add > Existing Frameworks. The framework in in /System/Library/Frameworks/
    • Add /System/Library/Frameworks/Python.framework/Headers to your "Header Search Path" (Project > Edit Project Settings)

    The following code should work (although it's probably not the best code ever written..)

    #include <Python.h>
    
    int main(){
        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
        Py_Initialize();
    
        // import urllib
        PyObject *mymodule = PyImport_Import(PyString_FromString("urllib"));
        // thefunc = urllib.urlopen
        PyObject *thefunc = PyObject_GetAttrString(mymodule, "urlopen");
    
        // if callable(thefunc):
        if(thefunc && PyCallable_Check(thefunc)){
            // theargs = ()
            PyObject *theargs = PyTuple_New(1);
    
            // theargs[0] = "http://google.com"
            PyTuple_SetItem(theargs, 0, PyString_FromString("http://google.com"));
    
            // f = thefunc.__call__(*theargs)
            PyObject *f = PyObject_CallObject(thefunc, theargs);
    
            // read = f.read
            PyObject *read = PyObject_GetAttrString(f, "read");
    
            // result = read.__call__()
            PyObject *result = PyObject_CallObject(read, NULL);
    
    
            if(result != NULL){
                // print result
                printf("Result of call: %s", PyString_AsString(result));
            }
        }
        [pool release];
    }
    

    Also this tutorial is good