SF Patch #441791, with changes: when "import foo.bar" fails with an

exception in the execution of bar, ensure that foo.bar exists.
(Previously, while sys.modules['foo.bar'] would exist, foo.bar would
only be created upon successful execution of bar.  This is
inconvenient; some would say wrong. :-)

diff --git a/Python/import.c b/Python/import.c
index 74437246325fd83e694079ffc93b80db6cc8efe3..456a5be6ff7a8fc9d8a451a19f3454e23abbdaea 100644 (file)
--- a/Python/import.c
+++ b/Python/import.c
@@ -1789,7 +1789,7 @@ static PyObject *
 import_submodule(PyObject *mod, char *subname, char *fullname)
 {
        PyObject *modules = PyImport_GetModuleDict();
-       PyObject *m;
+       PyObject *m, *res = NULL;
 
        /* Require:
           if mod == None: subname == fullname
@@ -1829,9 +1829,21 @@ import_submodule(PyObject *mod, char *subname, char *fullname)
                m = load_module(fullname, fp, buf, fdp->type);
                if (fp)
                        fclose(fp);
-               if (m != NULL && mod != Py_None) {
-                       if (PyObject_SetAttrString(mod, subname, m) < 0) {
-                               Py_DECREF(m);
+               if (mod != Py_None) {
+                       /* Irrespective of the success of this load, make a
+                          reference to it in the parent package module.
+                          A copy gets saved in the modules dictionary
+                          under the full name, so get a reference from
+                          there, if need be.  (The exception is when
+                          the load failed with a SyntaxError -- then
+                          there's no trace in sys.modules.  In that case,
+                          of course, do nothing extra.) */
+                       res = m;
+                       if (res == NULL)
+                               res = PyDict_GetItemString(modules, fullname);
+                       if (res != NULL &&
+                           PyObject_SetAttrString(mod, subname, res) < 0) {
+                               Py_XDECREF(m);
                                m = NULL;
                        }
                }