Explicitly prevent the instantiation of abstract classes

doc/Changelog.md

@@ -15,6 +15,7 @@ myst:
 
 ## Unreleased
 
+- {gh-pr}`202` {gh-issue}`188` Explicitly prevent instantiation of abstract classes.
 - {gh-pr}`201` {gh-issue}`185` Add `type` attribute to the load classes and rename branches `branch_type`
   attribute to `type` for consistency. Please replace `branch.branch_type` by `branch.type` in your code.
   In addition, loads data frames gained two new columns:

roseau/load_flow/models/branches.py

@@ -58,6 +58,8 @@ def __init__(
             geometry:
                 The geometry of the branch.
         """
+        if type(self) is AbstractBranch:
+            raise TypeError("Can't instantiate abstract class AbstractBranch")
         super().__init__(id, **kwargs)
         self._check_phases(id, phases1=phases1)
         self._check_phases(id, phases2=phases2)

roseau/load_flow/models/core.py

@@ -38,6 +38,8 @@ def __init__(self, id: Id, **kwargs: Any) -> None:
                 A unique ID of the element in the network. Two elements of the same type cannot
                 have the same ID.
         """
+        if type(self) is Element:
+            raise TypeError("Can't instantiate abstract class Element")
         super().__init__(id)
         self._connected_elements: list[Element] = []
         self._network: ElectricalNetwork | None = None

roseau/load_flow/models/loads/loads.py

@@ -56,6 +56,8 @@ def __init__(self, id: Id, bus: Bus, *, phases: str | None = None, **kwargs: Any
                 :attr:`allowed_phases`. All phases of the load, except ``"n"``, must be present in
                 the phases of the connected bus. By default, the phases of the bus are used.
         """
+        if type(self) is AbstractLoad:
+            raise TypeError("Can't instantiate abstract class AbstractLoad")
         super().__init__(id, **kwargs)
         if phases is None:
             phases = bus.phases

roseau/load_flow/models/tests/test_element.py

@@ -0,0 +1,14 @@
+import pytest
+
+from roseau.load_flow.models import AbstractBranch, AbstractLoad, Bus, Element
+
+
+def test_abstract_classes():
+    with pytest.raises(TypeError, match="Can't instantiate abstract class Element"):
+        Element("element_id")
+    bus1 = Bus("bus1", phases="an")
+    bus2 = Bus("bus2", phases="an")
+    with pytest.raises(TypeError, match="Can't instantiate abstract class AbstractBranch"):
+        AbstractBranch("branch_id", bus1=bus1, bus2=bus2, phases1="an", phases2="an")
+    with pytest.raises(TypeError, match="Can't instantiate abstract class AbstractLoad"):
+        AbstractLoad("load_id", bus=bus1, phases="an")