Type DecodePDU. (#2392)

Author: janiversen

pymodbus/client/base.py

@@ -66,7 +66,7 @@ async def connect(self) -> bool:
         )
         return await self.ctx.connect()
 
-    def register(self, custom_response_class: ModbusPDU) -> None:
+    def register(self, custom_response_class: type[ModbusPDU]) -> None:
         """Register a custom response class with the decoder (call **sync**).
 
         :param custom_response_class: (optional) Modbus response class.
@@ -197,7 +197,7 @@ def __init__(
     # ----------------------------------------------------------------------- #
     # Client external interface
     # ----------------------------------------------------------------------- #
-    def register(self, custom_response_class: ModbusPDU) -> None:
+    def register(self, custom_response_class: type[ModbusPDU]) -> None:
         """Register a custom response class with the decoder.
 
         :param custom_response_class: (optional) Modbus response class.

pymodbus/pdu/decoders.py

@@ -1,5 +1,5 @@
 """Modbus Request/Response Decoders."""
-from collections.abc import Callable
+from __future__ import annotations
 
 import pymodbus.pdu.bit_read_message as bit_r_msg
 import pymodbus.pdu.bit_write_message as bit_w_msg
@@ -17,7 +17,7 @@
 class DecodePDU:
     """Decode pdu requests/responses (server/client)."""
 
-    _pdu_class_table = {
+    _pdu_class_table: set[tuple[type[base.ModbusPDU], type[base.ModbusPDU]]] = {
         (reg_r_msg.ReadHoldingRegistersRequest, reg_r_msg.ReadHoldingRegistersResponse),
         (bit_r_msg.ReadDiscreteInputsRequest, bit_r_msg.ReadDiscreteInputsResponse),
         (reg_r_msg.ReadInputRegistersRequest, reg_r_msg.ReadInputRegistersResponse),
@@ -39,7 +39,7 @@ class DecodePDU:
         (mei_msg.ReadDeviceInformationRequest, mei_msg.ReadDeviceInformationResponse),
     }
 
-    _pdu_sub_class_table = [
+    _pdu_sub_class_table: set[tuple[type[base.ModbusPDU], type[base.ModbusPDU]]] = {
         (diag_msg.ReturnQueryDataRequest, diag_msg.ReturnQueryDataResponse),
         (diag_msg.RestartCommunicationsOptionRequest, diag_msg.RestartCommunicationsOptionResponse),
         (diag_msg.ReturnDiagnosticRegisterRequest, diag_msg.ReturnDiagnosticRegisterResponse),
@@ -58,57 +58,51 @@ class DecodePDU:
         (diag_msg.ClearOverrunCountRequest, diag_msg.ClearOverrunCountResponse),
         (diag_msg.GetClearModbusPlusRequest, diag_msg.GetClearModbusPlusResponse),
         (mei_msg.ReadDeviceInformationRequest, mei_msg.ReadDeviceInformationResponse),
-    ]
+    }
 
     def __init__(self, is_server: bool) -> None:
         """Initialize function_tables."""
         inx = 0 if is_server else 1
-        self.lookup: dict[int, Callable] = {cl[inx].function_code: cl[inx] for cl in self._pdu_class_table}  # type: ignore[attr-defined]
-        self.sub_lookup: dict[int, dict[int, Callable]] = {f: {} for f in self.lookup}
+        self.lookup: dict[int, type[base.ModbusPDU]] = {cl[inx].function_code: cl[inx] for cl in self._pdu_class_table}
+        self.sub_lookup: dict[int, dict[int, type[base.ModbusPDU]]] = {f: {} for f in self.lookup}
         for f in self._pdu_sub_class_table:
-            self.sub_lookup[f[inx].function_code][f[inx].sub_function_code] = f[inx]  # type: ignore[attr-defined]
+            self.sub_lookup[f[inx].function_code][f[inx].sub_function_code] = f[inx]
 
-    def lookupPduClass(self, function_code):
+    def lookupPduClass(self, function_code: int) -> type[base.ModbusPDU]:
         """Use `function_code` to determine the class of the PDU."""
         return self.lookup.get(function_code, base.ExceptionResponse)
 
-    def register(self, function):
+    def register(self, custom_class: type[base.ModbusPDU]) -> None:
         """Register a function and sub function class with the decoder."""
-        if not issubclass(function, base.ModbusPDU):
+        if not issubclass(custom_class, base.ModbusPDU):
             raise MessageRegisterException(
-                f'"{function.__class__.__name__}" is Not a valid Modbus Message'
+                f'"{custom_class.__class__.__name__}" is Not a valid Modbus Message'
                 ". Class needs to be derived from "
                 "`pymodbus.pdu.ModbusPDU` "
             )
-        self.lookup[function.function_code] = function
-        if hasattr(function, "sub_function_code"):
-            if function.function_code not in self.sub_lookup:
-                self.sub_lookup[function.function_code] = {}
-            self.sub_lookup[function.function_code][
-                function.sub_function_code
-            ] = function
+        self.lookup[custom_class.function_code] = custom_class
+        if custom_class.sub_function_code >= 0:
+            if custom_class.function_code not in self.sub_lookup:
+                self.sub_lookup[custom_class.function_code] = {}
+            self.sub_lookup[custom_class.function_code][
+                custom_class.sub_function_code
+            ] = custom_class
 
-    def decode(self, frame):
+    def decode(self, frame: bytes) -> base.ModbusPDU | None:
         """Decode a frame."""
         try:
             if (function_code := int(frame[0])) > 0x80:
-                pdu = base.ExceptionResponse(function_code & 0x7F)
-                pdu.decode(frame[1:])
-                return pdu
-            if (pdu := self.lookup.get(function_code, lambda: None)()):
-                fc_string = "{}: {}".format(  # pylint: disable=consider-using-f-string
-                    str(self.lookup[function_code])  # pylint: disable=use-maxsplit-arg
-                    .split(".")[-1]
-                    .rstrip('">"'),
-                    function_code,
-                )
-                Log.debug("decode PDU for {}", fc_string)
-            else:
+                pdu_exp = base.ExceptionResponse(function_code & 0x7F)
+                pdu_exp.decode(frame[1:])
+                return pdu_exp
+            if not (pdu_type := self.lookup.get(function_code, None)):
                 Log.debug("decode PDU failed for function code {}", function_code)
                 raise ModbusException(f"Unknown response {function_code}")
+            pdu = pdu_type(0, 0, False)
+            Log.debug("decode PDU for {}", function_code)
             pdu.decode(frame[1:])
 
-            if hasattr(pdu, "sub_function_code"):
+            if pdu.sub_function_code >= 0:
                 lookup = self.sub_lookup.get(pdu.function_code, {})
                 if subtype := lookup.get(pdu.sub_function_code, None):
                     pdu.__class__ = subtype

pymodbus/pdu/diag_message.py

@@ -61,9 +61,7 @@ def decode(self, data):
 
         :param data: The data to decode into the function code
         """
-        (
-            self.sub_function_code,  # pylint: disable=attribute-defined-outside-init
-        ) = struct.unpack(">H", data[:2])
+        (self.sub_function_code, ) = struct.unpack(">H", data[:2])
         if self.sub_function_code == ReturnQueryDataRequest.sub_function_code:
             self.message = data[2:]
         else:
@@ -123,9 +121,7 @@ def decode(self, data):
 
         :param data: The data to decode into the function code
         """
-        (
-            self.sub_function_code,  # pylint: disable=attribute-defined-outside-init
-        ) = struct.unpack(">H", data[:2])
+        (self.sub_function_code, ) = struct.unpack(">H", data[:2])
         data = data[2:]
         if self.sub_function_code == ReturnQueryDataRequest.sub_function_code:
             self.message = data

pymodbus/pdu/pdu.py

@@ -13,6 +13,7 @@ class ModbusPDU:
     """Base class for all Modbus messages."""
 
     function_code: int = 0
+    sub_function_code: int = -1
     _rtu_frame_size: int = 0
     _rtu_byte_count_pos: int = 0
 

pymodbus/server/simulator/http_server.py

@@ -390,7 +390,7 @@ def build_html_calls(self, params: dict, html: str) -> str:
         for function in self.request_lookup.values():
             selected = (
                 "selected"
-                if function.function_code == self.call_monitor.function  #type: ignore[attr-defined]
+                if function.function_code == self.call_monitor.function
                 else ""
             )
             function_codes += f"<option value={function.function_code} {selected}>{function.function_code_name}</option>"  #type: ignore[attr-defined]
@@ -556,9 +556,9 @@ def build_json_calls(self, params: dict) -> dict:
         function_codes = []
         for function in self.request_lookup.values():
             function_codes.append({
-                "value": function.function_code,    # type: ignore[attr-defined]
+                "value": function.function_code,
                 "text": function.function_code_name,    # type: ignore[attr-defined]
-                "selected": function.function_code == self.call_monitor.function  # type: ignore[attr-defined]
+                "selected": function.function_code == self.call_monitor.function
             })
 
         simulation_action = "ACTIVE" if self.call_response.active != RESPONSE_INACTIVE else ""