Make helmholtz backwards compatible (#248)

Author: jorgensd

chapter2/helmholtz_code.ipynb

@@ -143,16 +143,26 @@
    "outputs": [],
    "source": [
     "from mpi4py import MPI\n",
-    "from dolfinx import fem, io, default_scalar_type, geometry\n",
+    "from dolfinx import (\n",
+    "    fem,\n",
+    "    io,\n",
+    "    default_scalar_type,\n",
+    "    geometry,\n",
+    "    __version__ as dolfinx_version,\n",
+    ")\n",
     "from dolfinx.fem.petsc import LinearProblem\n",
     "import ufl\n",
     "import numpy as np\n",
     "import numpy.typing as npt\n",
+    "from packaging.version import Version\n",
     "\n",
     "mesh_data = io.gmshio.model_to_mesh(gmsh.model, MPI.COMM_WORLD, 0, gdim=3)\n",
-    "domain = mesh_data.mesh\n",
-    "assert mesh_data.facet_tags is not None\n",
-    "facet_tags = mesh_data.facet_tags"
+    "if Version(dolfinx_version) > Version(\"0.9.0\"):\n",
+    "    domain = mesh_data.mesh\n",
+    "    assert mesh_data.facet_tags is not None\n",
+    "    facet_tags = mesh_data.facet_tags\n",
+    "else:\n",
+    "    domain, _, facet_tags = mesh_data\n"
    ]
   },
   {

chapter2/helmholtz_code.py

@@ -63,16 +63,27 @@
 
 # +
 from mpi4py import MPI
-from dolfinx import fem, io, default_scalar_type, geometry
+from dolfinx import (
+    fem,
+    io,
+    default_scalar_type,
+    geometry,
+    __version__ as dolfinx_version,
+)
 from dolfinx.fem.petsc import LinearProblem
 import ufl
 import numpy as np
 import numpy.typing as npt
+from packaging.version import Version
 
 mesh_data = io.gmshio.model_to_mesh(gmsh.model, MPI.COMM_WORLD, 0, gdim=3)
-domain = mesh_data.mesh
-assert mesh_data.facet_tags is not None
-facet_tags = mesh_data.facet_tags
+if Version(dolfinx_version) > Version("0.9.0"):
+    domain = mesh_data.mesh
+    assert mesh_data.facet_tags is not None
+    facet_tags = mesh_data.facet_tags
+else:
+    domain, _, facet_tags = mesh_data
+
 # -
 
 # We define the function space for our unknown $p$ and define the range of frequencies we want to solve the Helmholtz equation for.