make failed reshape message less opaque

inducer · Sep 28, 2021 · 8f064ea · 8f064ea
1 parent 7813e53
commit 8f064ea
Showing 1 changed file with 15 additions and 6 deletions.
diff --git a/arraycontext/container/traversal.py b/arraycontext/container/traversal.py
@@ -530,9 +530,16 @@ def _flatten(subary: ArrayOrContainerT) -> None:
             except ValueError as exc:
                 # NOTE: we can't do much if the array context fails to ravel,
                 # since it is the one responsible for the actual memory layout
-                raise NotImplementedError("'flatten' requires advanced reshaping "
-                        "functionality that is not implemented in the array "
-                        f"context '{type(actx).__name__}'") from exc
+                if hasattr(subary, "strides"):
+                    strides_msg = f"and strides {subary.strides}"
+                else:
+                    strides_msg = ""
+
+                raise NotImplementedError(
+                        f"'{type(actx).__name__}.np.ravel' failed to reshape "
+                        f"an array with shape {subary.shape}{strides_msg}. "
+                        "This functionality needs to be implemented by the "
+                        "array context.") from exc
 
             result.append(flat_subary)
         else:
@@ -577,9 +584,11 @@ def _unflatten(template_subary: ArrayOrContainerT) -> ArrayOrContainerT:
             except ValueError as exc:
                 # NOTE: we can't do much if the array context fails to reshape,
                 # since it is the one responsible for the actual memory layout
-                raise NotImplementedError("'unflatten' requires advanced reshaping "
-                        "functionality that is not implemented in the array "
-                        f"context '{type(actx).__name__}'") from exc
+                raise NotImplementedError(
+                        f"'{type(actx).__name__}.np.reshape' failed to reshape "
+                        f"the flat array into shape {template_subary.shape}. "
+                        "This functionality needs to be implemented by the "
+                        "array context.") from exc
 
             if hasattr(template_subary, "strides"):
                 if template_subary.strides != subary.strides: