Do not deduplicate appended assets by a blank name (#8045)

project.append_asset reuses an existing profile, material, material set or
presentation style in the destination when it shares the appended asset's
Name. An empty or blank string was treated as a real key, so two distinct
assets that both have an empty name (e.g. two different
IfcArbitraryClosedProfileDef named "") collapsed into one on append (and
via the ExtractElements recipe). IfcMaterial had no guard at all.

Add is_reusable_name(), which accepts only a non-empty, non-blank string,
and use it for the name-based dedup of IfcProfileDef, IfcMaterial, the
material sets, and IfcPresentationStyle in both get_existing_element and
file_add. Blank/None-named assets are now appended as distinct instances;
non-empty names still dedup exactly as before, and rooted GUID-based reuse
is untouched.

Verified headless: two distinct blank-named profiles now yield two in the
destination (was one), a real-named pair still dedups to one, and
re-appending a named asset stays idempotent.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/ifcopenshell-python/ifcopenshell/api/project/append_asset.py

@@ -44,6 +44,18 @@ APPENDABLE_ASSET_TYPES: tuple[APPENDABLE_ASSET, ...] = get_args(APPENDABLE_ASSET
 MATERIAL_SETS = ("IfcMaterialLayerSet", "IfcMaterialConstituentSet", "IfcMaterialProfileSet")
 
 
+def is_reusable_name(name: Any) -> bool:
+    """Whether a name qualifies as a key for name-based deduplication.
+
+    Only a non-empty, non-blank string identifies an asset well enough to
+    reuse an existing one. An empty/blank string or ``None`` is not a real
+    name, so distinct blank-named assets (e.g. two different profiles both
+    named ``""``) must be appended as separate instances instead of collapsed
+    into one. See https://github.com/IfcOpenShell/IfcOpenShell/issues/8045.
+    """
+    return isinstance(name, str) and bool(name.strip())
+
+
 def append_asset(
     file: ifcopenshell.file,
     library: ifcopenshell.file,
@@ -315,14 +327,16 @@ class Usecase:
             return None
         elif element.is_a("IfcMaterial"):
             name = element.Name
+            if not is_reusable_name(name):
+                return None
             return next((e for e in self.file.by_type("IfcMaterial") if e.Name == name), None)
 
         elif element.is_a() in MATERIAL_SETS:
             ifc_class = element.is_a()
             name_attr = "LayerSetName" if ifc_class == "IfcMaterialLayerSet" else "Name"
             material_set_name = getattr(element, name_attr)
-            if material_set_name is None:
-                return
+            if not is_reusable_name(material_set_name):
+                return None
             for candidate in self.file.by_type(ifc_class):
                 if getattr(candidate, name_attr) == material_set_name:
                     if self.material_sets_are_equal(element, candidate):
@@ -331,12 +345,12 @@ class Usecase:
 
         elif element.is_a("IfcProfileDef"):
             profile_name = element.ProfileName
-            if profile_name is None:
+            if not is_reusable_name(profile_name):
                 return None
             return next((e for e in self.file.by_type("IfcProfileDef") if e.ProfileName == profile_name), None)
         elif element.is_a("IfcPresentationStyle"):
             name = element.Name
-            if name is None:
+            if not is_reusable_name(name):
                 return None
             return next((e for e in self.file.by_type(element.is_a()) if e.Name == name), None)
 
@@ -707,7 +721,7 @@ class Usecase:
         # then it might create duplicated subelements.
         if element.is_a("IfcProfileDef"):
             profile_name = element.ProfileName
-            if profile_name is not None:
+            if is_reusable_name(profile_name):
                 existing_profile = next(
                     (e for e in ifc_file.by_type("IfcProfileDef") if e.ProfileName == profile_name), None
                 )
@@ -717,15 +731,16 @@ class Usecase:
 
         elif element.is_a("IfcMaterial"):
             material_name = element.Name
-            existing_material = next((e for e in ifc_file.by_type("IfcMaterial") if e.Name == material_name), None)
-            if existing_material is not None:
-                reuse_identities[element_identity] = existing_material
-                return existing_material
+            if is_reusable_name(material_name):
+                existing_material = next((e for e in ifc_file.by_type("IfcMaterial") if e.Name == material_name), None)
+                if existing_material is not None:
+                    reuse_identities[element_identity] = existing_material
+                    return existing_material
 
         elif ifc_class in MATERIAL_SETS:
             name_attr = "LayerSetName" if ifc_class == "IfcMaterialLayerSet" else "Name"
             material_set_name = getattr(element, name_attr)
-            if material_set_name is not None:
+            if is_reusable_name(material_set_name):
                 for candidate in ifc_file.by_type(ifc_class):
                     if getattr(candidate, name_attr) == material_set_name:
                         if self.material_sets_are_equal(element, candidate):
@@ -734,7 +749,7 @@ class Usecase:
 
         elif element.is_a("IfcPresentationStyle"):
             style_name = element.Name
-            if style_name is not None:
+            if is_reusable_name(style_name):
                 existing_style = next((e for e in ifc_file.by_type(ifc_class) if e.Name == style_name), None)
                 if existing_style is not None:
                     reuse_identities[element_identity] = existing_style