🐍 Python codependent inheritance possible with Generic.

I might got inspired from reading spark / scala.

python/src/proto-inherit.py

@@ -54,14 +54,6 @@ def __init__(self) -> None:
         print("i inherit so much")
 
 
-MultiInheritNoParent()
-print()
-print()
-MultiInherit()
-
-print()
-
-
 class A(Protocol):
     @abc.abstractmethod
     def __init__(self) -> None:
@@ -80,3 +72,12 @@ def __init__(self) -> None:
     def f(self):
         super().f()
         print("B.f")
+
+
+if __name__ == "__main__":
+    MultiInheritNoParent()
+    print()
+    print()
+    MultiInherit()
+
+    print()

python/src/unpacking.py

@@ -23,4 +23,7 @@ def print_args_kwargs(*args, **kwargs):
     print(kwargs)
 
 
-print_args_kwargs(*CustomIter(), **CustomMapping())
+if __name__ == "__main__":
+    # Despite them not being `Iterable` or `Mapping` subclasses,
+    # it still would work.
+    print_args_kwargs(*CustomIter(), **CustomMapping())

python/src/variance.py

@@ -460,6 +460,29 @@ def attack_and_defend(self) -> None:
             self.b.defend(self.a)
 
 
+def codependent_generic():
+    # Using generic to solve this.
+    # I think I noticed this is possible by reading the source code of spark.
+    _B = TypeVar("_B", bound="B")
+    _A = TypeVar("_A", bound="A")
+
+    class A(Generic[_B]):
+        def attack(self, b: _B) -> None:
+            print(self, "attacking", b)
+
+    class B(Generic("_A")):
+        def defend(self, a: "_A") -> None:
+            print(self, "defending", a)
+
+    class SubA(A[SubB]):
+        def attack(self, b: "SubB") -> None:
+            return super().attack(b)
+
+    class SubB(B["SubA"]):
+        def defend(self, a: "SubA") -> None:
+            return super().defend(a)
+
+
 if __name__ == "__main__":
     g_ng()
     ng_g()
@@ -478,3 +501,6 @@ def attack_and_defend(self) -> None:
     print()
     print("co dependent generics")
     codependent()
+
+    # How come I din't think of this?
+    codependent_generic()