custom extension capability

CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+* Added `extensions` keyword argument to `Model` to for inserting custom extensions to IFC classes.
+
 ### Changed
 
 ### Removed

scripts/6.1_custom_extension.py

@@ -0,0 +1,23 @@
+from compas_ifc.entities.generated.IFC4 import IfcBuildingElement
+from compas_ifc.model import Model
+
+
+class ExtendedIfcBuildingElement(IfcBuildingElement):
+    @property
+    def volume(self):
+        return self.geometry.volume
+
+
+model = Model("data/Duplex_A_20110907.ifc", use_occ=True, extensions={"IfcBuildingElement": ExtendedIfcBuildingElement})
+
+total_wall_volume = 0
+for wall in model.get_entities_by_type("IfcWall"):
+    total_wall_volume += wall.volume
+
+print("Total wall volume:", total_wall_volume, f"{model.unit}³")
+
+total_slab_volume = 0
+for slab in model.get_entities_by_type("IfcSlab"):
+    total_slab_volume += slab.volume
+
+print("Total slab volume:", total_slab_volume, f"{model.unit}³")

src/compas_ifc/entities/base.py

@@ -34,7 +34,7 @@ class Base(Data):
     file : Ifcfile
     """
 
-    def __new__(cls, entity: entity_instance, file: "IFCFile" = None):
+    def __new__(cls, entity: entity_instance, file: "IFCFile" = None, extensions: dict = None):
         if file is None:
             schema = "IFC4"
         else:
@@ -48,11 +48,24 @@ def __new__(cls, entity: entity_instance, file: "IFCFile" = None):
         cls_name = entity.is_a()
         ifc_cls = getattr(classes, cls_name, None)
         if ifc_cls:
-            return super(Base, cls).__new__(ifc_cls)
+            matched_extensions = []
+            if extensions:
+                for name, extension_class in extensions.items():
+                    if entity.is_a(name):
+                        matched_extensions.append(extension_class)
+            if matched_extensions:
+                # Create a new class that inherits from the original IFC class and all matched extensions
+                extension_name = f"Extended{cls_name}"
+                bases = tuple([ifc_cls] + matched_extensions)
+                extended_cls = type(extension_name, bases, {})
+                return super(Base, extended_cls).__new__(extended_cls)
+            else:
+                # If no extensions matched, use the original IFC class
+                return super(Base, ifc_cls).__new__(ifc_cls)
         elif hasattr(entity, "wrappedValue"):
             return TypeDefinition(entity, file)
 
-    def __init__(self, entity: entity_instance = None, file=None):
+    def __init__(self, entity: entity_instance = None, file=None, **kwargs):
         super().__init__()
         self.file = file
         self.entity = entity

src/compas_ifc/file.py

@@ -16,7 +16,8 @@
 
 
 class IFCFile(object):
-    def __init__(self, model, filepath=None, schema="IFC4", use_occ=False, load_geometries=True, verbose=True):
+    def __init__(self, model, filepath=None, schema="IFC4", use_occ=False, load_geometries=True, verbose=True, extensions=None):
+        self.extensions = extensions
         self.verbose = verbose
         self.ensure_classes_generated()
         self._entitymap = {}
@@ -96,7 +97,7 @@ def from_entity(self, entity):
         if _id in self._entitymap and _id != 0:
             return self._entitymap[_id]
         else:
-            entity = Base(entity, self)
+            entity = Base(entity, file=self, extensions=self.extensions)
             if _id != 0:
                 self._entitymap[_id] = entity
             return entity

src/compas_ifc/model.py

@@ -17,8 +17,8 @@
 
 
 class Model(Data):
-    def __init__(self, filepath=None, schema=None, use_occ=False, load_geometries=True, verbose=True):
-        self.file = IFCFile(self, filepath=filepath, schema=schema, use_occ=use_occ, load_geometries=load_geometries, verbose=verbose)
+    def __init__(self, filepath=None, schema=None, use_occ=False, load_geometries=True, verbose=True, extensions=None):
+        self.file = IFCFile(self, filepath=filepath, schema=schema, use_occ=use_occ, load_geometries=load_geometries, verbose=verbose, extensions=extensions)
         if filepath:
             self.update_linear_deflection()