fix: minor issues in Snapshot class

src/snapshot.py

@@ -6,7 +6,7 @@ from typing import Optional
 
 import numpy as np
 
-from vec import Vec
+from src.vec import Vec
 
 
 def iter_unpack(format, data):
@@ -20,7 +20,7 @@ class Snapshot:
     position: Vec = field(default_factory=Vec)
     direction: Vec = field(default_factory=Vec)
     speed: float = 0
-    raycast_distances: list[float] | tuple[float, ...] = [0]
+    raycast_distances: list[float] | tuple[float, ...] = field(default_factory=list)
     image: Optional[np.ndarray] = None
 
     def pack(self):
@@ -46,19 +46,29 @@ class Snapshot:
 
         return data
 
-    def unpack(self, data):
-        self.controls, data = iter_unpack(">BBBB", data)
+    @staticmethod
+    def unpack(data: bytes) -> Snapshot:
+        controls, data = iter_unpack(">BBBB", data)
         (x, y, dx, dy, s), data = iter_unpack(">fffff", data)
-        self.position = Vec(x, y)
-        self.direction = Vec(dx, dy)
-        self.speed = s
+        position = Vec(x, y)
+        direction = Vec(dx, dy)
+        speed = s
 
         (nbr_raycasts,), data = iter_unpack(">B", data)
-        self.raycast_distances, data = iter_unpack(f">{nbr_raycasts}f", data)
+        raycast_distances, data = iter_unpack(f">{nbr_raycasts}f", data)
 
         (h, w), data = iter_unpack(">ii", data)
 
         if h * w > 0:
-            self.image = np.frombuffer(data, np.uint8).reshape(h, w, 3)
+            image = np.frombuffer(data, np.uint8).reshape(h, w, 3)
         else:
-            self.image = None
+            image = None
+
+        return Snapshot(
+            controls=controls,
+            position=position,
+            direction=direction,
+            speed=speed,
+            raycast_distances=raycast_distances,
+            image=image,
+        )