refactor: lets reverse_gear and reverse_steering return new objects

reeds_shepp.py

@@ -44,10 +44,12 @@ def __repr__(self):
         return s
 
     def reverse_steering(self):
-        self.steering = Steering(-self.steering.value)
+        steering = Steering(-self.steering.value)
+        return replace(self, steering=steering)
 
     def reverse_gear(self):
-        self.gear = Gear(-self.gear.value)
+        gear = Gear(-self.gear.value)
+        return replace(self, gear=gear)
 
 
 def path_length(path):
@@ -70,6 +72,7 @@ def get_optimal_path(start, end):
             L_min, i_min = L, i
     return paths[i_min]
 
+
 def get_all_paths(start, end):
     """
     Return a list of all the paths from start to end generated by the
@@ -103,24 +106,18 @@ def timeflip(path):
     """
     timeflip transform described around the end of the article
     """
-    new_path = [replace(e) for e in path]
-    for e in new_path:
-        e.reverse_gear()
+    new_path = [e.reverse_gear() for e in path]
     return new_path
 
 
 def reflect(path):
     """
     reflect transform described around the end of the article
     """
-    new_path = [replace(e) for e in path]
-    for e in new_path:
-        e.reverse_steering()
+    new_path = [e.reverse_steering() for e in path]
     return new_path
 
 
-
-
 def path1(x, y, phi):
     """
     Formula 8.1: CSC (same turns)

test_reeds_shepp.py

@@ -13,16 +13,14 @@ def test_repr(self):
         )
 
     def test_reverse_gear(self):
-        self.element.reverse_gear()
         self.assertEqual(
-            self.element.gear,
+            self.element.reverse_gear().gear,
             Gear.BACKWARD
         )
 
     def test_reverse_steering(self):
-        self.element.reverse_steering()
         self.assertEqual(
-            self.element.steering,
+            self.element.reverse_steering().steering,
             Steering.RIGHT
         )