PYTHON API : add new classes in a module from an other module

Alex Martelli aleaxit at
Wed Sep 1 14:35:31 CEST 2004

mathieu gontier <mg.mailing-list at> wrote:
>           foo_module = Py_GetModule( "FOO" ) ;
>           if( ! foo_module ) return ;
> So, my question is : does it exist in the Python API, a equivalent 
> function of  "Py_GetModule( <module name> )" (that a have invented for
> the example !)  ;
> or does an other solution exist in order to do the same think ?

There is no direct way to "get a module named this way if it is already
imported otherwise do nothing".  PyImport_AddModule comes close, but it
will return an empty module (and insert it into sys.modules too...) in
the 'otherwise' case.

PyImport_GetModuleDict  returns sys.module to you as a PyObject*
(borrowed reference, so no worry about needing to decref it later), and
then you can call PyDict_GetItemString on it -- the latter DOES return 0
without setting and exception if the string isn't a key in the
dictionary, so overall it may come closest to your desires even though
you do need a two-calls sequence.

Summarizing, then:

    PyObject* sys_modules = PyImport_GetModuleDict();
    PyObject* foo_module = PyDict_GetItemString(sys_modules, "FOO");
    if(!foo_module) return;

    /* use foo_module freely here, do not decref it when you're done */



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