Add get_main().

ericsnowcurrently · ericsnowcurrently · commit 271d20de5777 · 2017-12-11T18:37:29.000-07:00
diff --git a/Doc/library/_interpreters.rst b/Doc/library/_interpreters.rst
@@ -41,6 +41,11 @@ It defines the following functions:
    Return the ID of the currently running interpreter.
 
 
+.. function:: get_main()
+
+   Return the ID of the main interpreter.
+
+
 .. function:: is_running(id)
 
    Return whether or not the identified interpreter is currently
diff --git a/Lib/test/test__interpreters.py b/Lib/test/test__interpreters.py
@@ -111,6 +111,16 @@ def test_sub(self):
         self.assertEqual(id2, id1)
 
 
+class GetMainTests(TestBase):
+
+    def test_main(self):
+        expected, = interpreters.enumerate()
+        main = interpreters.get_main()
+
+        self.assertEqual(main, 0)
+        self.assertEqual(main, expected)
+
+
 class IsRunningTests(TestBase):
 
     def test_main_running(self):
diff --git a/Modules/_interpretersmodule.c b/Modules/_interpretersmodule.c
@@ -467,6 +467,19 @@ PyDoc_STRVAR(get_current_doc,
 Return the ID of current interpreter.");
 
 
+static PyObject *
+interp_get_main(PyObject *self)
+{
+    // Currently, 0 is always the main interpreter.
+    return PyLong_FromLongLong(0);
+}
+
+PyDoc_STRVAR(get_main_doc,
+"get_main() -> ID\n\
+\n\
+Return the ID of main interpreter.");
+
+
 static PyObject *
 interp_run_string(PyObject *self, PyObject *args)
 {
@@ -571,6 +584,8 @@ static PyMethodDef module_functions[] = {
      METH_NOARGS, enumerate_doc},
     {"get_current",             (PyCFunction)interp_get_current,
      METH_NOARGS, get_current_doc},
+    {"get_main",                (PyCFunction)interp_get_main,
+     METH_NOARGS, get_main_doc},
     {"is_running",              (PyCFunction)interp_is_running,
      METH_VARARGS, is_running_doc},
 
