From a20f0d58919ff8f3cb7d9b9df906f18be7536ee6 Mon Sep 17 00:00:00 2001
From: Matthias Koefferlein <matthias@koefferlein.de>
Date: Mon, 31 Aug 2020 23:55:26 +0200
Subject: [PATCH] Also provide 'void to self' return values for Python.

---
 src/pya/pya/pyaModule.cc         | 15 +++++++++++++++
 testdata/python/dbPolygonTest.py | 11 +++++++++++
 2 files changed, 26 insertions(+)

diff --git a/src/pya/pya/pyaModule.cc b/src/pya/pya/pyaModule.cc
index 31d3961d3..5c16ce6e3 100644
--- a/src/pya/pya/pyaModule.cc
+++ b/src/pya/pya/pyaModule.cc
@@ -686,6 +686,15 @@ property_name_from_id (int mid, PyObject *self)
   return cls_decl->name () + "." + mt->property_name (mid);
 }
 
+static gsi::ArgType create_void_type ()
+{
+  gsi::ArgType at;
+  at.init<void> ();
+  return at;
+}
+
+static gsi::ArgType s_void_type = create_void_type ();
+
 static PyObject *
 get_return_value (PYAObjectBase *self, gsi::SerialArgs &retlist, const gsi::MethodBase *meth, tl::Heap &heap)
 {
@@ -696,6 +705,12 @@ get_return_value (PYAObjectBase *self, gsi::SerialArgs &retlist, const gsi::Meth
     gsi::IterAdaptorAbstractBase *iter = (gsi::IterAdaptorAbstractBase *) retlist.read<gsi::IterAdaptorAbstractBase *> (heap);
     ret = (PyObject *) PYAIteratorObject::create (self ? self->py_object () : 0, iter, &meth->ret_type ());
 
+  } else if (meth->ret_type () == s_void_type && self != 0) {
+
+    //  simple, yet magical :)
+    ret = self->py_object ();
+    Py_INCREF (ret);
+
   } else {
 
     ret = pop_arg (meth->ret_type (), retlist, self, heap).release ();
diff --git a/testdata/python/dbPolygonTest.py b/testdata/python/dbPolygonTest.py
index f98597d07..64cf8e471 100644
--- a/testdata/python/dbPolygonTest.py
+++ b/testdata/python/dbPolygonTest.py
@@ -728,6 +728,17 @@ class DBPolygonTests(unittest.TestCase):
     self.assertEqual(str(p1), "(21,42;21,62;41,62;41,42)")
     self.assertEqual(str(pp), "(21,42;21,62;41,62;41,42)")
 
+  def test_voidMethodsReturnSelf(self):
+
+    hull =  [ pya.Point(0, 0),       pya.Point(6000, 0), 
+              pya.Point(6000, 3000), pya.Point(0, 3000) ]
+    hole1 = [ pya.Point(1000, 1000), pya.Point(2000, 1000), 
+              pya.Point(2000, 2000), pya.Point(1000, 2000) ]
+    hole2 = [ pya.Point(3000, 1000), pya.Point(4000, 1000), 
+              pya.Point(4000, 2000), pya.Point(3000, 2000) ]
+    poly = pya.Polygon(hull).insert_hole(hole1).insert_hole(hole2)
+    self.assertEqual(str(poly), "(0,0;0,3000;6000,3000;6000,0/1000,1000;2000,1000;2000,2000;1000,2000/3000,1000;4000,1000;4000,2000;3000,2000)")
+
 # run unit tests
 if __name__ == '__main__':
   suite = unittest.TestLoader().loadTestsFromTestCase(DBPolygonTests)