Delete shared default options after context

petsctools/options.py

@@ -499,14 +499,15 @@ def __init__(self, parameters: dict[str, Any],
         else:
             default_options = {}
 
+        # Start building parameters from the defaults so
+        # that they will overwritten by any other source.
+        parameters = default_options | parameters
+        inherited_options = set(default_options)
+
         # The parameters to drop from the global options when we leave the
         # inserted_options context. This is everything except for options
         # passed on the command line.
         to_delete = set(parameters.keys())
-
-        # Start building parameters from the defaults so
-        # that they will overwritten by any other source.
-        parameters = default_options | parameters
         unsafe_options = []
         for full_key, v in self.options_object.getAll().items():
             if full_key.startswith(options_prefix):
@@ -516,9 +517,10 @@ def __init__(self, parameters: dict[str, Any],
                 key = full_key[len(options_prefix):]
                 parameters[key] = v
 
-                # option is set globally, don't drop when we exit the
-                # context manager
-                to_delete.discard(key)
+                # Keep existing options, except inherited defaults, which
+                # are temporary copies under this prefix.
+                if key not in inherited_options:
+                    to_delete.discard(key)
         if unsafe_options:
             unsafe_options_str = "\n".join(
                 f"  {opt}" for opt in unsafe_options

tests/test_options.py

@@ -179,6 +179,31 @@ def test_default_options():
     assert options2.parameters["opt4"] == "6"
 
 
+@pytest.mark.skipnopetsc4py
+def test_inserted_options_deletes_default_options():
+    """Check that inserted_options removes the options that the
+    OptionsManager inherits from its default options set, and keeps
+    the options that the database already held."""
+    from petsc4py import PETSc
+
+    options = PETSc.Options()
+    options["parent_ksp_type"] = "cg"
+    options["parent_0_pc_type"] = "jacobi"
+    opts_before = dict(options.getAll())
+
+    child = petsctools.OptionsManager(
+        parameters={},
+        options_prefix="parent_0",
+        default_options_set=petsctools.DefaultOptionSet("parent", [0]))
+    assert child.parameters == {"ksp_type": "cg", "pc_type": "jacobi"}
+
+    with child.inserted_options():
+        pass
+
+    assert options.getAll() == opts_before
+    assert "parent_0_ksp_type" not in options
+
+
 @pytest.mark.skipnopetsc4py
 def test_python_options_with_manager():
     petsctools.init()