#3189 proposal (#3190)

src/ifcopenshell-python/ifcopenshell/entity_instance.py

@@ -131,6 +131,13 @@ class entity_instance(object):
         """
         self.wrapped_data.file = None
 
+    @property
+    def file(self):
+        # ugh circular imports, name collisions
+        from . import file
+
+        return file.file.from_pointer(self.wrapped_data.file_pointer())
+
     def __getattr__(self, name):
         INVALID, FORWARD, INVERSE = range(3)
         attr_cat = self.wrapped_data.get_attribute_category(name)

src/ifcopenshell-python/ifcopenshell/file.py

@@ -176,6 +176,9 @@ class Transaction:
                 pass
 
 
+file_dict = {}
+
+
 class file(object):
     """Base class for containing IFC files.
 
@@ -249,6 +252,8 @@ class file(object):
         self.future = []
         self.transaction = None
 
+        file_dict[self.file_pointer()] = self
+
     def set_history_size(self, size):
         self.history_size = size
         while len(self.history) > self.history_size:
@@ -543,10 +548,18 @@ class file(object):
             unzipped_path = path.with_suffix(format)
             path.rename(unzipped_path)
             with zipfile.ZipFile(path, "w") as zip_file:
-                zip_file.write(unzipped_path, unzipped_path.name, compress_type=zipfile.ZIP_DEFLATED)
+                zip_file.write(
+                    unzipped_path,
+                    unzipped_path.name,
+                    compress_type=zipfile.ZIP_DEFLATED,
+                )
                 unzipped_path.unlink()
         return
 
     @staticmethod
     def from_string(s):
         return file(ifcopenshell_wrapper.read(s))
+
+    @staticmethod
+    def from_pointer(v):
+        return file_dict.get(v)

src/ifcwrap/IfcParseWrapper.i

@@ -116,6 +116,12 @@ static IfcUtil::ArgumentType helper_fn_attribute_type(const IfcUtil::IfcBaseClas
 %}
 
 %extend IfcParse::IfcFile {
+	// Use to correlate to entity_instance.file_pointer, so that we
+	// can trace file ownership of instances on the python side.
+	size_t file_pointer() const {
+		return reinterpret_cast<size_t>($self);
+	}
+
 	IfcUtil::IfcBaseClass* by_guid(const std::string& guid) {
 		return $self->instance_by_guid(guid);
 	}