Document use of _set_up function and fix test to raise ValueError

desc/transform.py

@@ -78,9 +78,7 @@ def __init__(
         self._method = method
         # assign according to logic in setter function
         self.method = method
-        # assign according to logic in property function
-        self._matrices = None
-        self._matrices = self.matrices
+        self._matrices = self._get_matrices()
         if build:
             self.build()
         if build_pinv:
@@ -130,6 +128,18 @@ def _sort_derivatives(self):
         )
         self._derivatives = self.derivatives[sort_idx]
 
+    def _get_matrices(self):
+        """Get matrices to compute all derivatives."""
+        n = np.amax(self.derivatives) + 1
+        matrices = {
+            "direct1": {
+                i: {j: {k: {} for k in range(n)} for j in range(n)} for i in range(n)
+            },
+            "fft": {i: {j: {} for j in range(n)} for i in range(n)},
+            "direct2": {i: {} for i in range(n)},
+        }
+        return matrices
+
     def _check_inputs_fft(self, grid, basis):
         """Check that inputs are formatted correctly for fft method."""
         if grid.num_nodes == 0 or basis.num_modes == 0:
@@ -716,32 +726,24 @@ def change_derivatives(self, derivs, build=True):
         self._sort_derivatives()
 
         if len(derivs_to_add):
-            # if we actually added derivatives and didn't build them, then its not built
+            # if we actually added derivatives and didn't build them, then it's not built
             self._built = False
         if build:
             # we don't update self._built here because it is still built from before,
             # but it still might have unbuilt matrices from new derivatives
             self.build()
 
     def _set_up(self):
-        # fixme? dummy method needed for _matrices attribute to persist?
-        self.method = self.method
+        """Recreate attributes that were not saved to output files."""
+        # fixme: Make api for reloading attributes that are not saved better.
+        # See equilibrium_io.py for the logic that calls this function.
         self._matrices = self.matrices
 
     @property
     def matrices(self):
         """dict: transform matrices such that x=A*c."""
-        if getattr(self, "_matrices", None) is None:
-            # to allow computing of highest order derivative
-            n = np.amax(self.derivatives) + 1
-            self._matrices = {
-                "direct1": {
-                    i: {j: {k: {} for k in range(n)} for j in range(n)}
-                    for i in range(n)
-                },
-                "fft": {i: {j: {} for j in range(n)} for i in range(n)},
-                "direct2": {i: {} for i in range(n)},
-            }
+        if not hasattr(self, "_matrices"):
+            self._matrices = self._get_matrices()
         return self._matrices
 
     @property

tests/test_curves.py

@@ -256,7 +256,7 @@ def test_misc(self):
     def test_asserts(self):
         """Test error checking when creating FourierXYZCurve."""
         c = FourierXYZCurve()
-        with pytest.raises(KeyError):
+        with pytest.raises(ValueError):
             c.compute_coordinates(dt=4)
         with pytest.raises(TypeError):
             c.grid = [1, 2, 3]