Revert examples/seismic/model.py to use legacy SubDomain API

The new SubDomain API (passing grid= to SubDomain constructor) breaks
Dask pickling/unpickling, causing AttributeError when Grid is deserialized.

Reverting to the legacy API (passing subdomains= to Grid constructor)
which works correctly with Dask, even though it triggers a deprecation
warning. This is acceptable until the new API is fixed to work with Dask.

Author: ggorman

examples/seismic/model.py

@@ -59,10 +59,10 @@ class PhysicalDomain(SubDomain):
 
     name = 'physdomain'
 
-    def __init__(self, so, fs=False, **kwargs):
+    def __init__(self, so, fs=False):
+        super().__init__()
         self.so = so
         self.fs = fs
-        super().__init__(**kwargs)
 
     def define(self, dimensions):
         map_d = {d: d for d in dimensions}
@@ -75,9 +75,9 @@ class FSDomain(SubDomain):
 
     name = 'fsdomain'
 
-    def __init__(self, so, **kwargs):
+    def __init__(self, so):
+        super().__init__()
         self.size = so
-        super().__init__(**kwargs)
 
     def define(self, dimensions):
         """
@@ -105,7 +105,11 @@ def __init__(self, origin, spacing, shape, space_order, nbl=20,
         shape_pml = np.array(shape) + 2 * self.nbl
 
         # Model size depending on freesurface
+        physdomain = PhysicalDomain(space_order, fs=fs)
+        subdomains = subdomains + (physdomain,)
         if fs:
+            fsdomain = FSDomain(space_order)
+            subdomains = subdomains + (fsdomain,)
             origin_pml[-1] = origin[-1]
             shape_pml[-1] -= self.nbl
 
@@ -115,23 +119,10 @@ def __init__(self, origin, spacing, shape, space_order, nbl=20,
             # Physical extent is calculated per cell, so shape - 1
             extent = tuple(np.array(spacing) * (shape_pml - 1))
             self.grid = Grid(extent=extent, shape=shape_pml, origin=origin_pml,
-                             dtype=dtype, topology=topology)
+                             dtype=dtype, subdomains=subdomains, topology=topology)
         else:
             self.grid = grid
 
-        # Create subdomains with grid parameter (new pattern)
-        physdomain = PhysicalDomain(space_order, fs=fs, grid=self.grid)
-        # Register physdomain
-        self.grid._subdomains = self.grid._subdomains + (physdomain,)
-
-        # Register user-provided subdomains
-        self.grid._subdomains = self.grid._subdomains + subdomains
-
-        if fs:
-            fsdomain = FSDomain(space_order, grid=self.grid)
-            # Register fsdomain
-            self.grid._subdomains = self.grid._subdomains + (fsdomain,)
-
         self._physical_parameters = set()
         self.damp = None
         self._initialize_bcs(bcs=bcs)