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

src/ifcopenshell-python/ifcopenshell/api/constraint/add_objective.py

@@ -0,0 +1,15 @@
+import ifcopenshell
+
+class Usecase:
+    def __init__(self, file, settings={}):
+        self.file = file
+        self.settings = {}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        return self.file.create_entity("IfcObjective", **{
+            "Name": "Unnamed",
+            "ConstraintGrade": "NOTDEFINED",
+            "ObjectiveQualifier": "NOTDEFINED"
+        })

src/ifcopenshell-python/ifcopenshell/api/constraint/assign_constraint.py

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+import ifcopenshell
+
+
+class Usecase:
+    def __init__(self, file, settings=None):
+        self.file = file
+        self.settings = {
+            "product": None,
+            "constraint": None,
+        }
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        rel = self.get_constraint_rel()
+        related_objects = set(rel.RelatedObjects) if rel.RelatedObjects else set()
+        related_objects.add(self.settings["product"])
+        rel.RelatedObjects = list(related_objects)
+
+    def get_constraint_rel(self):
+        for rel in self.file.by_type("IfcRelAssociatesConstraint"):
+            if rel.RelatingConstraint == self.settings["constraint"]:
+                return rel
+        return self.file.create_entity("IfcRelAssociatesConstraint", **{
+            "GlobalId": ifcopenshell.guid.new(),
+            # TODO: owner history
+            "RelatingConstraint": self.settings["constraint"]
+        })

src/ifcopenshell-python/ifcopenshell/api/constraint/data.py

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+import ifcopenshell
+import ifcopenshell.util.date
+from datetime import datetime
+
+
+class Data:
+    is_loaded = False
+    products = {}
+    objectives = {}
+
+    @classmethod
+    def purge(cls):
+        cls.is_loaded = False
+        cls.products = {}
+        cls.objectives = {}
+
+    @classmethod
+    def load(cls, file, product_id=None):
+        cls._file = file
+        if not cls._file:
+            return
+        if product_id:
+            return cls.load_product(product_id)
+        cls.load_objectives()
+        cls.is_loaded = True
+
+    @classmethod
+    def load_product(cls, product_id):
+        product = cls._file.by_id(product_id)
+        cls.products[product_id] = []
+        if not product.HasAssociations:
+            return
+        for association in product.HasAssociations:
+            if association.is_a("IfcRelAssociatesConstraint"):
+                if not association.RelatingConstraint.is_a("IfcObjective"):
+                    continue  # not yet implemented
+                cls.products[product_id].append(association.RelatingConstraint.id())
+
+    @classmethod
+    def load_objectives(cls):
+        cls.objectives = {}
+        for constraint in cls._file.by_type("IfcObjective"):
+            data = constraint.get_info()
+            if cls._file.schema == "IFC2X3":
+                for attribute in ["CreationTime"]:
+                    if data[attribute]:
+                        data[attribute] = ifcopenshell.util.date.ifc2datetime(data[attribute]).isoformat()
+            cls.objectives[constraint.id()] = data

src/ifcopenshell-python/ifcopenshell/api/constraint/edit_objective.py

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+class Usecase:
+    def __init__(self, file, settings=None):
+        self.file = file
+        self.settings = {
+            "objective": None,
+            "attributes": {}
+        }
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        for name, value in self.settings["attributes"].items():
+            setattr(self.settings["objective"], name, value)

src/ifcopenshell-python/ifcopenshell/api/constraint/remove_constraint.py

@@ -0,0 +1,12 @@
+class Usecase:
+    def __init__(self, file, settings=None):
+        self.file = file
+        self.settings = {"constraint": None}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        self.file.remove(self.settings["constraint"])
+        for rel in self.file.by_type("IfcRelAssociatesConstraint"):
+            if not rel.RelatingConstraint:
+                self.file.remove(rel)

src/ifcopenshell-python/ifcopenshell/api/constraint/unassign_constraint.py

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+import ifcopenshell
+
+
+class Usecase:
+    def __init__(self, file, settings=None):
+        self.file = file
+        self.settings = {
+            "product": None,
+            "constraint": None,
+        }
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        for rel in self.settings["product"].HasAssociations:
+            if rel.is_a("IfcRelAssociatesConstraint") and rel.RelatingConstraint == self.settings["constraint"]:
+                self.file.remove(rel)