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

src/ifcopenshell-python/ifcopenshell/api/classification/add_classification.py

@@ -0,0 +1,39 @@
+import ifcopenshell
+import ifcopenshell.util.schema
+import ifcopenshell.util.date
+
+class Usecase:
+    def __init__(self, file, settings=None):
+        self.file = file
+        self.settings = {
+            "classification": None,
+        }
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        edition_date = None
+        if self.settings["classification"].EditionDate:
+            edition_date = ifcopenshell.util.date.ifc2datetime(self.settings["classification"].EditionDate)
+            self.settings["classification"].EditionDate = None
+
+        migrator = ifcopenshell.util.schema.Migrator()
+        result = migrator.migrate(self.settings["classification"], self.file)
+
+        # TODO: should auto date migration be part of the migrator?
+        if self.file.schema == "IFC2X3" and edition_date:
+            result.EditionDate = ifcopenshell.util.date.datetime2ifc(edition_date, "IfcCalendarDate")
+        else:
+            result.EditionDate = ifcopenshell.util.date.datetime2ifc(edition_date, "IfcDate")
+
+        self.file.create_entity("IfcRelAssociatesClassification", **{
+            "GlobalId": ifcopenshell.guid.new(),
+            "RelatedObjects": [self.file.by_type("IfcProject")[0]],
+            "RelatingClassification": result
+        })
+        return # See bug #1272
+        try:
+            result = self.file.add(self.settings["classification"])
+        except:
+            migrator = ifcopenshell.util.schema.Migrator()
+            result = migrator.migrate(self.settings["classification"], self.file)