Improve challenges with alternative solutions and hints (#125)

* Add alternative solution in advanced-forward challenge

"from __future__ import annotations"

* Improve extreme-self-casting challenge

* Improve advanced-variadic-generics challenge

Author: LoicRiegel

challenges/advanced-forward/solution.py

@@ -8,6 +8,19 @@ def copy(self) -> "MyClass":
         return copied_object
 
 
+# Alternative soltion:
+#
+# from __future__ import annotations
+# class MyClass:
+#     def __init__(self, x: int) -> None:
+#         self.x = x
+# 
+#     # TODO: Fix the type hints of `copy` to make it type check
+#     def copy(self) -> MyClass:
+#         copied_object = MyClass(x=self.x)
+#         return copied_object
+
+
 ## End of your code ##
 
 from typing import assert_type

challenges/advanced-variadic-generics/hints.md

@@ -0,0 +1 @@
+Check out [TypeVarTuple](https://docs.python.org/3/library/typing.html#typing.TypeVarTuple).

challenges/advanced-variadic-generics/solution.py

@@ -4,13 +4,15 @@
 Define an `Array` type that supports element-wise addition of arrays with identical dimensions and types.
 """
 
-from typing import Generic, TypeVar, TypeVarTuple, assert_type
-
-T = TypeVar("T")
-Ts = TypeVarTuple("Ts")
-
-
-class Array(Generic[*Ts]):
+# For Python < 3.12
+# Ts = TypeVarTuple("Ts")
+#
+# class Array(Generic[*Ts]):
+#     def __add__(self, other: "Array[*Ts]") -> "Array[*Ts]":
+#         ...
+
+# For Python >= 3.12
+class Array[*Ts]:
     def __add__(self, other: "Array[*Ts]") -> "Array[*Ts]":
         ...
 

challenges/advanced-variadic-generics/solution2.py

@@ -0,0 +1 @@
+Checkout [ParamSpec](https://docs.python.org/3/library/typing.html#typing.ParamSpec) and [Concatenate](https://docs.python.org/3/library/typing.html#typing.Concatenate).

challenges/extreme-self-casting/hints.md

@@ -12,16 +12,25 @@
 
 from typing import Callable, Concatenate, Generic, ParamSpec, TypeVar
 
-
-R = TypeVar("R")
-P = ParamSpec("P")
-
-
-class Fn(Generic[R, P]):
-    def __init__(self, f: Callable[P, R]):
+# # For Python < 3.12
+# R = TypeVar("R")
+# P = ParamSpec("P")
+# 
+# 
+# class Fn(Generic[R, P]):
+#     def __init__(self, f: Callable[P, R]):
+#         self.f = f
+# 
+#     def transform_callable(self) -> Callable[Concatenate[object, P], R]:
+#         ...
+
+
+# For Python >= 3.12
+class Fn[R, **P]:
+    def __init__(self, f: Callable[P, R]) -> None:
         self.f = f
 
-    def transform_callable(self) -> Callable[Concatenate[object, P], R]:
+    def transform_callable(self) -> Callable[Concatenate[Any, P], R]:
         ...