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

src/ifcopenshell-python/ifcopenshell/api/pset/edit_qto.py

@@ -0,0 +1,72 @@
+import blenderbim.bim.schema  # TODO: refactor
+
+
+class Usecase:
+    def __init__(self, file, settings=None):
+        self.file = file
+        self.settings = {"qto": None, "Name": None, "Properties": {}}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        self.update_qto_name()
+        self.load_qto_template()
+        self.update_existing_properties()
+        new_properties = self.add_new_properties()
+        self.extend_qto_with_new_properties(new_properties)
+
+    def update_qto_name(self):
+        if self.settings["Name"]:
+            self.settings["qto"].Name = self.settings["Name"]
+
+    def load_qto_template(self):
+        self.qto_template = blenderbim.bim.schema.ifc.psetqto.get_by_name(self.settings["qto"].Name)
+
+    def update_existing_properties(self):
+        for prop in self.settings["qto"].Quantities or []:
+            self.update_existing_property(prop)
+
+    def update_existing_property(self, prop):
+        if prop.Name not in self.settings["Properties"]:
+            return
+        value = self.settings["Properties"][prop.Name]
+        if prop.is_a("IfcPhysicalSimpleQuantity"):
+            prop[3] = float(value) if value else None
+        del self.settings["Properties"][prop.Name]
+
+    def add_new_properties(self):
+        properties = []
+        for name, value in self.settings["Properties"].items():
+            if value is None:
+                continue
+            property_type = self.get_canonical_property_type(name)
+            properties.append(
+                self.file.create_entity(
+                    "IfcQuantity{}".format(property_type),
+                    **{"Name": name, "{}Value".format(property_type): value},
+                )
+            )
+        return properties
+
+    def extend_qto_with_new_properties(self, new_properties):
+        props = list(self.settings["qto"].Quantities) if self.settings["qto"].Quantities else []
+        props.extend(new_properties)
+        self.settings["qto"].Quantities = props
+
+    def get_canonical_property_type(self, name):
+        if not self.qto_template:
+            return "Length"
+        for prop_template in self.qto_template.HasPropertyTemplates:
+            if prop_template.Name != name:
+                continue
+            return prop_template.TemplateType[2:].lower().capitalize()
+        return "Length"
+
+    def get_primary_measure_type(self, name, previous_value=None):
+        if not self.qto_template:
+            return previous_value.is_a() if previous_value else "IfcLabel"
+        for prop_template in self.qto_template.HasPropertyTemplates:
+            if prop_template.Name != name:
+                continue
+            return prop_template.PrimaryMeasureType or "IfcLabel"
+        return previous_value.is_a() if previous_value else "IfcLabel"