Adding type annotations to several packets

We are still getting mypy complaints about the Liskov Principle,
and quarternion due to trying to return the sum of a bytes and an
int. Need to flag this as an issue.

Author: HundredVisionsGuy

adafruit_bluefruit_connect/magnetometer_packet.py

@@ -12,14 +12,16 @@
 
 """
 
+from __future__ import annotations
+
 from ._xyz_packet import _XYZPacket
 
 
 class MagnetometerPacket(_XYZPacket):
     """A packet of x, y, z float values from a magnetometer."""
 
     # Everything else is handled by _XYZPacket.
-    _TYPE_HEADER = b"!M"
+    _TYPE_HEADER: bytes = b"!M"
 
 
 # Register this class with the superclass. This allows the user to import only what is needed.

adafruit_bluefruit_connect/quaternion_packet.py

@@ -12,6 +12,8 @@
 
 """
 
+from __future__ import annotations
+
 import struct
 
 from ._xyz_packet import _XYZPacket
@@ -23,26 +25,26 @@ class QuaternionPacket(_XYZPacket):
 
     # Use _XYZPacket to handle x, y, z, and add w.
 
-    _FMT_PARSE = "<xxffffx"
-    PACKET_LENGTH = struct.calcsize(_FMT_PARSE)
+    _FMT_PARSE: str = "<xxffffx"
+    PACKET_LENGTH: int = struct.calcsize(_FMT_PARSE)
     # _FMT_CONSTRUCT doesn't include the trailing checksum byte.
-    _FMT_CONSTRUCT = "<2sffff"
-    _TYPE_HEADER = b"!Q"
+    _FMT_CONSTRUCT: str = "<2sffff"
+    _TYPE_HEADER: bytes = b"!Q"
 
-    def __init__(self, x, y, z, w):
+    def __init__(self, x: float, y: float, z: float, w: float) -> None:
         """Construct a QuaternionPacket from the given x, y, z, and w float values."""
         super().__init__(x, y, z)
         self._w = w
 
-    def to_bytes(self):
+    def to_bytes(self) -> bytes:
         """Return the bytes needed to send this packet."""
         partial_packet = struct.pack(
             self._FMT_CONSTRUCT, self._TYPE_HEADER, self._x, self._y, self._z, self._w
         )
         return partial_packet + self.checksum(partial_packet)
 
     @property
-    def w(self):
+    def w(self) -> float:
         """The w value."""
         return self._w
 

adafruit_bluefruit_connect/raw_text_packet.py

@@ -22,23 +22,25 @@
 
 """
 
+from __future__ import annotations
+
 from .packet import Packet
 
 
 class RawTextPacket(Packet):
     """A packet containing a text string."""
 
-    _TYPE_HEADER = b"RT"
+    _TYPE_HEADER: bytes = b"RT"
 
-    def __init__(self, text):
+    def __init__(self, text: str) -> None:
         """Construct a RawTextPacket from a binary string."""
         if isinstance(text, bytes):
-            self._text = text.strip()
+            self._text: str = text.strip()
         else:
             raise ValueError("Text must be a bytes string")
 
     @property
-    def text(self):
+    def text(self) -> str:
         """Return the text associated with the object."""
         return self._text