PyInterpreter: minor cleanup and improvements

PyCore/Embed/PyInterpreter.cpp

@@ -151,8 +151,7 @@ PyObjectPtr PyInterpreter::import(const std::string& pymodule_name, const std::s
 {
     ASSERT(!pymodule_name.empty());
 
-    if (!path.empty())
-        addPythonPath(path);
+    addPythonPath(path);
 
     // import the module
     PyObject* pymodule = PyImport_ImportModule(pymodule_name.c_str());
@@ -170,6 +169,10 @@ PyObjectPtr PyInterpreter::import(const std::string& pymodule_name, const std::s
 // Python stable ABI
 void PyInterpreter::DecRef(PyObject* py_object)
 {
+    // Decrementing Python reference-count without
+    // Python initialized leads to memory access violation (segmentation fault)
+    ASSERT(PyInterpreter::isInitialized());
+
     Py_XDECREF(py_object);
 }
 
@@ -225,7 +228,6 @@ void PyInterpreter::callFunction(PyObject* py_module, const std::string& fn_name
     Py_DecRef(pFunc);
 }
 
-
 std::string PyInterpreter::runtimeInfo()
 {
     std::string result;
@@ -305,8 +307,7 @@ std::string PyInterpreter::errorDescription(const std::string& title)
 
 PyObjectPtr PyInterpreter::BornAgain::import(const std::string& path)
 {
-    if (!path.empty())
-        PyInterpreter::addPythonPath(path);
+    PyInterpreter::addPythonPath(path);
 
 #ifndef _WIN32
     // store ctrl-C handler before Numpy messes it up
@@ -389,6 +390,10 @@ std::vector<std::string> PyInterpreter::BornAgain::listOfFunctions(const std::st
 {
     PyObjectPtr tmpModule{PyInterpreter::BornAgain::importScript(script, path)};
 
+    if (!tmpModule.valid())
+        throw std::runtime_error("PyInterpreter::BornAgain: "
+                                 "Cannot obtain the dictionary from the script module");
+
     PyObject* pDict = PyModule_GetDict(tmpModule.get());
     if (!pDict) {
         checkError();
@@ -402,11 +407,13 @@ std::vector<std::string> PyInterpreter::BornAgain::listOfFunctions(const std::st
     while (PyDict_Next(pDict, &pos, &key, &value)) {
         if (PyCallable_Check(value)) {
             std::string func_name{PyInterpreter::pyStrtoString(key)};
+            // do not import callables whose names begin with '__'
             if (func_name.find("__") == std::string::npos)
                 fn_names.push_back(func_name);
         }
     }
-    PyDict_Clear(pDict); // do not accumulate history between imports
+
+    Py_DecRef(pDict);
     return fn_names;
 }