Defining types in return dictionaries (commaai#1923)

* Defining types in return dictionaries

* Correcting indent

* Returning the class instead of dict

* Fixing failing linter

* Fixing whitespace error

python/ccp.py

@@ -2,6 +2,35 @@
 import time
 import struct
 from enum import IntEnum, Enum
+from dataclasses import dataclass
+from typing import Optional
+
+@dataclass
+class ExchangeStationIdsReturn:
+  id_length: int
+  data_type: int
+  available: int
+  protected: int
+
+@dataclass
+class GetDaqListSizeReturn:
+  list_size: int
+  first_pid: int
+
+@dataclass
+class GetSessionStatusReturn:
+  status: int
+  info: Optional[int]
+
+@dataclass
+class DiagnosticServiceReturn:
+  length: int
+  type: int
+
+@dataclass
+class ActionServiceReturn:
+  length: int
+  type: int
 
 class COMMAND_CODE(IntEnum):
   CONNECT = 0x01
@@ -140,15 +169,10 @@ def connect(self, station_addr: int) -> None:
     self._send_cro(COMMAND_CODE.CONNECT, struct.pack("<H", station_addr))
     self._recv_dto(0.025)
 
-  def exchange_station_ids(self, device_id_info: bytes = b"") -> dict:
+  def exchange_station_ids(self, device_id_info: bytes = b"") -> ExchangeStationIdsReturn:
     self._send_cro(COMMAND_CODE.EXCHANGE_ID, device_id_info)
     resp = self._recv_dto(0.025)
-    return { # TODO: define a type
-      "id_length": resp[0],
-      "data_type": resp[1],
-      "available": resp[2],
-      "protected": resp[3],
-    }
+    return ExchangeStationIdsReturn(id_length=resp[0], data_type=resp[1], available=resp[2], protected=resp[3])
 
   def get_seed(self, resource_mask: int) -> bytes:
     if resource_mask > 255:
@@ -211,15 +235,12 @@ def select_calibration_page(self) -> None:
     self._send_cro(COMMAND_CODE.SELECT_CAL_PAGE)
     self._recv_dto(0.025)
 
-  def get_daq_list_size(self, list_num: int, can_id: int = 0) -> dict:
+  def get_daq_list_size(self, list_num: int, can_id: int = 0) -> GetDaqListSizeReturn:
     if list_num > 255:
       raise ValueError("list number must be less than 256")
     self._send_cro(COMMAND_CODE.GET_DAQ_SIZE, bytes([list_num, 0]) + struct.pack(f"{self.byte_order.value}I", can_id))
     resp = self._recv_dto(0.025)
-    return { # TODO: define a type
-      "list_size": resp[0],
-      "first_pid": resp[1],
-    }
+    return GetDaqListSizeReturn(list_size=resp[0], first_pid=resp[1])
 
   def set_daq_list_pointer(self, list_num: int, odt_num: int, element_num: int) -> None:
     if list_num > 255:
@@ -266,13 +287,11 @@ def set_session_status(self, status: int) -> None:
     self._send_cro(COMMAND_CODE.SET_S_STATUS, bytes([status]))
     self._recv_dto(0.025)
 
-  def get_session_status(self) -> dict:
+  def get_session_status(self) -> GetSessionStatusReturn:
     self._send_cro(COMMAND_CODE.GET_S_STATUS)
     resp = self._recv_dto(0.025)
-    return { # TODO: define a type
-      "status": resp[0],
-      "info": resp[2] if resp[1] else None,
-    }
+    info = resp[2] if resp[1] else None
+    return GetSessionStatusReturn(status=resp[0], info=info)
 
   def build_checksum(self, size: int) -> bytes:
     self._send_cro(COMMAND_CODE.BUILD_CHKSUM, struct.pack(f"{self.byte_order.value}I", size))
@@ -310,29 +329,23 @@ def move_memory_block(self, size: int) -> None:
     self._send_cro(COMMAND_CODE.MOVE, struct.pack(f"{self.byte_order.value}I", size))
     self._recv_dto(0.025)
 
-  def diagnostic_service(self, service_num: int, data: bytes = b"") -> dict:
+  def diagnostic_service(self, service_num: int, data: bytes = b"") -> DiagnosticServiceReturn:
     if service_num > 65535:
       raise ValueError("service number must be less than 65536")
     if len(data) > 4:
       raise ValueError("max data size is 4 bytes")
     self._send_cro(COMMAND_CODE.DIAG_SERVICE, struct.pack(f"{self.byte_order.value}H", service_num) + data)
     resp = self._recv_dto(0.025)
-    return { # TODO: define a type
-      "length": resp[0],
-      "type": resp[1],
-    }
+    return DiagnosticServiceReturn(length=resp[0], type=resp[1])
 
-  def action_service(self, service_num: int, data: bytes = b"") -> dict:
+  def action_service(self, service_num: int, data: bytes = b"") -> ActionServiceReturn:
     if service_num > 65535:
       raise ValueError("service number must be less than 65536")
     if len(data) > 4:
       raise ValueError("max data size is 4 bytes")
     self._send_cro(COMMAND_CODE.ACTION_SERVICE, struct.pack(f"{self.byte_order.value}H", service_num) + data)
     resp = self._recv_dto(0.025)
-    return { # TODO: define a type
-      "length": resp[0],
-      "type": resp[1],
-    }
+    return ActionServiceReturn(length=resp[0], type=resp[1])
 
   def test_availability(self, station_addr: int) -> None:
     if station_addr > 65535: