First attempt at ripping out agnostic code into ifcopenshell.api namespace. See #1399.

src/ifcopenshell-python/ifcopenshell/api/root/copy_class.py

@@ -0,0 +1,37 @@
+import ifcopenshell
+
+
+class Usecase:
+    def __init__(self, file, settings=None):
+        self.file = file
+        self.settings = {"product": None}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        result = self.file.create_entity(self.settings["product"].is_a())
+        self.schema = ifcopenshell.ifcopenshell_wrapper.schema_by_name(self.file.schema)
+        self.copy_attributes(self.settings["product"], result)
+        for inverse in self.file.get_inverse(self.settings["product"]):
+            for i, value in enumerate(inverse):
+                if value == self.settings["product"]:
+                    new_inverse = self.file.create_entity(inverse.is_a())
+                    self.copy_attributes(inverse, new_inverse)
+                    new_inverse[i] = result
+                elif isinstance(value, (tuple, list)) and self.settings["product"] in value:
+                    new_value = list(value)
+                    new_value.append(result)
+                    inverse[i] = new_value
+        if result.is_a("IfcProduct"):
+            result.Representation = None
+        elif result.is_a("IfcTypeProduct"):
+            result.RepresentationMaps = None
+        return result
+
+    def copy_attributes(self, from_element, to_element):
+        declaration = self.schema.declaration_by_name(from_element.is_a())
+        for attribute in declaration.all_attributes():
+            if attribute.name() == "GlobalId":
+                setattr(to_element, attribute.name(), ifcopenshell.guid.new())
+            else:
+                setattr(to_element, attribute.name(), getattr(from_element, attribute.name()))