Python sum, why not strings? [closed]

Answer 1

Here's the source: http://svn.python.org/view/python/trunk/Python/bltinmodule.c?revision=81029&view=markup

In the builtin_sum function we have this bit of code:

     /* reject string values for 'start' parameter */
        if (PyObject_TypeCheck(result, &PyBaseString_Type)) {
            PyErr_SetString(PyExc_TypeError,
                "sum() can't sum strings [use ''.join(seq) instead]");
            Py_DECREF(iter);
            return NULL;
        }
        Py_INCREF(result);
    }

So.. that's your answer.

It's explicitly checked in the code and rejected.