just use py::objects and py::none

nifty_gridder.cc

@@ -634,22 +634,18 @@ template<typename T> class Helper
 template<typename T> pyarr_c<complex<T>> vis2grid_c(
   const Baselines<T> &baselines, const GridderConfig<T> &gconf,
   const pyarr_c<uint32_t> &idx_, const pyarr_c<complex<T>> &vis_,
-  pyarr_c<complex<T>> * user_grid)
+  py::object user_grid)
   {
   checkArray(vis_, "vis", {0});
   size_t nvis = size_t(vis_.shape(0));
   size_t nu=gconf.Nu(), nv=gconf.Nv();
   checkArray(idx_, "idx", {nvis});
 
-  printf("user_grid %p %d\n", user_grid, user_grid == nullptr);
-
-  if(user_grid)
-      { checkArray(*user_grid, "user_grid", {nu, nv}); }
-
   auto vis=vis_.data();
   auto idx = idx_.data();
 
-  auto res = user_grid ? makeArray<complex<T>>({nu, nv}) : *user_grid;
+  auto res = !user_grid.is(py::none()) ? user_grid.cast<pyarr_c<complex<T>>>()
+                                       : makeArray<complex<T>>({nu, nv});
   auto grid = res.mutable_data();
   {
   py::gil_scoped_release release;
@@ -690,8 +686,7 @@ template<typename T> pyarr_c<T> vis2grid(const Baselines<T> &baselines,
   const pyarr_c<complex<T>> &vis_)
   {
     return complex2hartley(vis2grid_c(baselines, gconf,
-                                      idx_, vis_,
-                                      static_cast<pyarr_c<std::complex<T>> *>(nullptr)));
+                                      idx_, vis_, py::none()));
   }
 
 template<typename T> pyarr_c<complex<T>> ms2grid_c(

test.py

 import nifty_gridder as ng
 import numpy as np
 import pytest
-from numpy.testing import assert_, assert_allclose
+from numpy.testing import assert_, assert_allclose, assert_array_almost_equal
 
 pmp = pytest.mark.parametrize
 
@@ -62,12 +62,12 @@ def test_hoisted_grid_allocation(nxdirty, nydirty, nrow, nchan, epsilon):
     vis = baselines.ms2vis(ms, idx)
     user_grid = np.zeros((gconf.Nu(), gconf.Nv()),
                          dtype=np.complex128)
-    grid = ng.vis2grid_c(baselines, gconf, idx, vis, user_grid=user_grid)
+    grid = ng.vis2grid_c(baselines, gconf, idx, vis, user_grid=None)
 
-    # Same base array under the hood
-    assert grid.base is user_grid.base
+    grid2 = ng.vis2grid_c(baselines, gconf, idx, vis, user_grid=user_grid)
 
-    ng.vis2grid_c(baselines, gconf, idx, vis, user_grid=None)
+    assert_array_almost_equal(grid, grid2)
+    assert id(grid2) == id(user_grid)
 
 
 def test_pickling():