[ILibraryView / Pattern] flatten() should raise PatternError if asked to preserve ports from a repeated ref

masque/library.py

@@ -308,6 +308,11 @@ class ILibraryView(Mapping[str, 'Pattern'], metaclass=ABCMeta):
                     continue
 
                 for ref in pat.refs[target]:
+                    if flatten_ports and ref.repetition is not None and target_pat.ports:
+                        raise PatternError(
+                            f'Cannot flatten ports from repeated ref to {target!r}; '
+                            'flatten with flatten_ports=False or expand/rename the ports manually first.'
+                            )
                     p = ref.as_pattern(pattern=target_pat)
                     if not flatten_ports:
                         p.ports.clear()

masque/pattern.py

@@ -1082,6 +1082,11 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
                     continue
 
                 for ref in refs:
+                    if flatten_ports and ref.repetition is not None and target_pat.ports:
+                        raise PatternError(
+                            f'Cannot flatten ports from repeated ref to {target!r}; '
+                            'flatten with flatten_ports=False or expand/rename the ports manually first.'
+                            )
                     p = ref.as_pattern(pattern=target_pat)
                     if not flatten_ports:
                         p.ports.clear()

masque/test/test_library.py

@@ -77,6 +77,20 @@ def test_library_flatten_preserves_ports_only_child() -> None:
     assert tuple(flat_parent.ports["P1"].offset) == (11.0, 12.0)
 
 
+def test_library_flatten_repeated_ref_with_ports_raises() -> None:
+    lib = Library()
+    child = Pattern(ports={"P1": Port((1, 2), 0)})
+    child.polygon((1, 0), vertices=[[0, 0], [1, 0], [0, 1]])
+    lib["child"] = child
+
+    parent = Pattern()
+    parent.ref("child", repetition=Grid(a_vector=(10, 0), a_count=2))
+    lib["parent"] = parent
+
+    with pytest.raises(PatternError, match='Cannot flatten ports from repeated ref'):
+        lib.flatten("parent", flatten_ports=True)
+
+
 def test_lazy_library() -> None:
     lib = LazyLibrary()
     called = 0

masque/test/test_pattern.py

@@ -114,6 +114,18 @@ def test_pattern_flatten_preserves_ports_only_child() -> None:
     assert parent.ports["P1"].rotation == 0
     assert tuple(parent.ports["P1"].offset) == (11.0, 12.0)
 
+
+def test_pattern_flatten_repeated_ref_with_ports_raises() -> None:
+    child = Pattern(ports={"P1": Port((1, 2), 0)})
+    child.polygon((1, 0), vertices=[[0, 0], [1, 0], [0, 1]])
+
+    parent = Pattern()
+    parent.ref("child", repetition=Grid(a_vector=(10, 0), a_count=2))
+
+    with pytest.raises(PatternError, match='Cannot flatten ports from repeated ref'):
+        parent.flatten({"child": child}, flatten_ports=True)
+
+
 def test_pattern_interface() -> None:
     source = Pattern()
     source.ports["A"] = Port((10, 20), 0, ptype="test")