Specific Exceptions: Adapting systec interface

can/interfaces/systec/__init__.py

@@ -1,4 +1 @@
-"""
-"""
-
 from can.interfaces.systec.ucanbus import UcanBus

can/interfaces/systec/exceptions.py

@@ -1,92 +1,107 @@
+from typing import Dict
+
+from abc import ABC, abstractmethod
+
 from .constants import ReturnCode
 from can import CanError
 
 
-class UcanException(CanError):
-    """ Base class for USB can errors. """
+class UcanException(CanError, ABC):
+    """Base class for USB can errors."""
 
     def __init__(self, result, func, arguments):
-        self.result = result.value
+        self.result = result
         self.func = func
         self.arguments = arguments
-        self.return_msgs = {}
-        super().__init__()
 
-    def __str__(self):
-        message = self.return_msgs.get(self.result, "unknown")
-        return f"Function {self.func.__name__} returned {self.result}: {message}"
+        message = self._error_message_mapping.get(result, "unknown")
+        super().__init__(
+            message=f"Function {func.__name__} (called with {arguments}): {message}",
+            error_code=result.value,
+        )
+
+    @property
+    @abstractmethod
+    def _error_message_mapping(self) -> Dict[ReturnCode, str]:
+        ...
 
 
 class UcanError(UcanException):
-    """ Exception class for errors from USB-CAN-library. """
+    """Exception class for errors from USB-CAN-library."""
 
-    def __init__(self, result, func, arguments):
-        super().__init__(result, func, arguments)
-        self.return_msgs = {
-            ReturnCode.ERR_RESOURCE: "could not created a resource (memory, handle, ...)",
-            ReturnCode.ERR_MAXMODULES: "the maximum number of opened modules is reached",
-            ReturnCode.ERR_HWINUSE: "the specified module is already in use",
-            ReturnCode.ERR_ILLVERSION: "the software versions of the module and library are incompatible",
-            ReturnCode.ERR_ILLHW: "the module with the specified device number is not connected "
-            "(or used by an other application)",
-            ReturnCode.ERR_ILLHANDLE: "wrong USB-CAN-Handle handed over to the function",
-            ReturnCode.ERR_ILLPARAM: "wrong parameter handed over to the function",
-            ReturnCode.ERR_BUSY: "instruction can not be processed at this time",
-            ReturnCode.ERR_TIMEOUT: "no answer from module",
-            ReturnCode.ERR_IOFAILED: "a request to the driver failed",
-            ReturnCode.ERR_DLL_TXFULL: "a CAN message did not fit into the transmit buffer",
-            ReturnCode.ERR_MAXINSTANCES: "maximum number of applications is reached",
-            ReturnCode.ERR_CANNOTINIT: "CAN interface is not yet initialized",
-            ReturnCode.ERR_DISCONECT: "USB-CANmodul was disconnected",
-            ReturnCode.ERR_NOHWCLASS: "the needed device class does not exist",
-            ReturnCode.ERR_ILLCHANNEL: "illegal CAN channel",
-            ReturnCode.ERR_RESERVED1: "reserved",
-            ReturnCode.ERR_ILLHWTYPE: "the API function can not be used with this hardware",
-        }
+    _ERROR_MESSAGES = {
+        ReturnCode.ERR_RESOURCE: "could not created a resource (memory, handle, ...)",
+        ReturnCode.ERR_MAXMODULES: "the maximum number of opened modules is reached",
+        ReturnCode.ERR_HWINUSE: "the specified module is already in use",
+        ReturnCode.ERR_ILLVERSION: "the software versions of the module and library are incompatible",
+        ReturnCode.ERR_ILLHW: "the module with the specified device number is not connected "
+        "(or used by an other application)",
+        ReturnCode.ERR_ILLHANDLE: "wrong USB-CAN-Handle handed over to the function",
+        ReturnCode.ERR_ILLPARAM: "wrong parameter handed over to the function",
+        ReturnCode.ERR_BUSY: "instruction can not be processed at this time",
+        ReturnCode.ERR_TIMEOUT: "no answer from module",
+        ReturnCode.ERR_IOFAILED: "a request to the driver failed",
+        ReturnCode.ERR_DLL_TXFULL: "a CAN message did not fit into the transmit buffer",
+        ReturnCode.ERR_MAXINSTANCES: "maximum number of applications is reached",
+        ReturnCode.ERR_CANNOTINIT: "CAN interface is not yet initialized",
+        ReturnCode.ERR_DISCONECT: "USB-CANmodul was disconnected",
+        ReturnCode.ERR_NOHWCLASS: "the needed device class does not exist",
+        ReturnCode.ERR_ILLCHANNEL: "illegal CAN channel",
+        ReturnCode.ERR_RESERVED1: "reserved",
+        ReturnCode.ERR_ILLHWTYPE: "the API function can not be used with this hardware",
+    }
+
+    @property
+    def _error_message_mapping(self) -> Dict[ReturnCode, str]:
+        return UcanError._ERROR_MESSAGES
 
 
 class UcanCmdError(UcanException):
-    """ Exception class for errors from firmware in USB-CANmodul."""
+    """Exception class for errors from firmware in USB-CANmodul."""
 
-    def __init__(self, result, func, arguments):
-        super().__init__(result, func, arguments)
-        self.return_msgs = {
-            ReturnCode.ERRCMD_NOTEQU: "the received response does not match to the transmitted command",
-            ReturnCode.ERRCMD_REGTST: "no access to the CAN controller",
-            ReturnCode.ERRCMD_ILLCMD: "the module could not interpret the command",
-            ReturnCode.ERRCMD_EEPROM: "error while reading the EEPROM",
-            ReturnCode.ERRCMD_RESERVED1: "reserved",
-            ReturnCode.ERRCMD_RESERVED2: "reserved",
-            ReturnCode.ERRCMD_RESERVED3: "reserved",
-            ReturnCode.ERRCMD_ILLBDR: "illegal baud rate value specified in BTR0/BTR1 for systec "
-            "USB-CANmoduls",
-            ReturnCode.ERRCMD_NOTINIT: "CAN channel is not initialized",
-            ReturnCode.ERRCMD_ALREADYINIT: "CAN channel is already initialized",
-            ReturnCode.ERRCMD_ILLSUBCMD: "illegal sub-command specified",
-            ReturnCode.ERRCMD_ILLIDX: "illegal index specified (e.g. index for cyclic CAN messages)",
-            ReturnCode.ERRCMD_RUNNING: "cyclic CAN message(s) can not be defined because transmission of "
-            "cyclic CAN messages is already running",
-        }
+    _ERROR_MESSAGES = {
+        ReturnCode.ERRCMD_NOTEQU: "the received response does not match to the transmitted command",
+        ReturnCode.ERRCMD_REGTST: "no access to the CAN controller",
+        ReturnCode.ERRCMD_ILLCMD: "the module could not interpret the command",
+        ReturnCode.ERRCMD_EEPROM: "error while reading the EEPROM",
+        ReturnCode.ERRCMD_RESERVED1: "reserved",
+        ReturnCode.ERRCMD_RESERVED2: "reserved",
+        ReturnCode.ERRCMD_RESERVED3: "reserved",
+        ReturnCode.ERRCMD_ILLBDR: "illegal baud rate value specified in BTR0/BTR1 for systec "
+        "USB-CANmoduls",
+        ReturnCode.ERRCMD_NOTINIT: "CAN channel is not initialized",
+        ReturnCode.ERRCMD_ALREADYINIT: "CAN channel is already initialized",
+        ReturnCode.ERRCMD_ILLSUBCMD: "illegal sub-command specified",
+        ReturnCode.ERRCMD_ILLIDX: "illegal index specified (e.g. index for cyclic CAN messages)",
+        ReturnCode.ERRCMD_RUNNING: "cyclic CAN message(s) can not be defined because transmission of "
+        "cyclic CAN messages is already running",
+    }
+
+    @property
+    def _error_message_mapping(self) -> Dict[ReturnCode, str]:
+        return UcanCmdError._ERROR_MESSAGES
 
 
 class UcanWarning(UcanException):
-    """ Exception class for warnings, the function has been executed anyway. """
+    """Exception class for warnings, the function has been executed anyway."""
 
-    def __init__(self, result, func, arguments):
-        super().__init__(result, func, arguments)
-        self.return_msgs = {
-            ReturnCode.WARN_NODATA: "no CAN messages received",
-            ReturnCode.WARN_SYS_RXOVERRUN: "overrun in receive buffer of the kernel driver",
-            ReturnCode.WARN_DLL_RXOVERRUN: "overrun in receive buffer of the USB-CAN-library",
-            ReturnCode.WARN_RESERVED1: "reserved",
-            ReturnCode.WARN_RESERVED2: "reserved",
-            ReturnCode.WARN_FW_TXOVERRUN: "overrun in transmit buffer of the firmware (but this CAN message "
-            "was successfully stored in buffer of the ibrary)",
-            ReturnCode.WARN_FW_RXOVERRUN: "overrun in receive buffer of the firmware (but this CAN message "
-            "was successfully read)",
-            ReturnCode.WARN_FW_TXMSGLOST: "reserved",
-            ReturnCode.WARN_NULL_PTR: "pointer is NULL",
-            ReturnCode.WARN_TXLIMIT: "not all CAN messages could be stored to the transmit buffer in "
-            "USB-CAN-library",
-            ReturnCode.WARN_BUSY: "reserved",
-        }
+    _ERROR_MESSAGES = {
+        ReturnCode.WARN_NODATA: "no CAN messages received",
+        ReturnCode.WARN_SYS_RXOVERRUN: "overrun in receive buffer of the kernel driver",
+        ReturnCode.WARN_DLL_RXOVERRUN: "overrun in receive buffer of the USB-CAN-library",
+        ReturnCode.WARN_RESERVED1: "reserved",
+        ReturnCode.WARN_RESERVED2: "reserved",
+        ReturnCode.WARN_FW_TXOVERRUN: "overrun in transmit buffer of the firmware (but this CAN message "
+        "was successfully stored in buffer of the ibrary)",
+        ReturnCode.WARN_FW_RXOVERRUN: "overrun in receive buffer of the firmware (but this CAN message "
+        "was successfully read)",
+        ReturnCode.WARN_FW_TXMSGLOST: "reserved",
+        ReturnCode.WARN_NULL_PTR: "pointer is NULL",
+        ReturnCode.WARN_TXLIMIT: "not all CAN messages could be stored to the transmit buffer in "
+        "USB-CAN-library",
+        ReturnCode.WARN_BUSY: "reserved",
+    }
+
+    @property
+    def _error_message_mapping(self) -> Dict[ReturnCode, str]:
+        return UcanWarning._ERROR_MESSAGES

can/interfaces/systec/ucan.py

@@ -4,6 +4,8 @@
 from ctypes import byref
 from ctypes import c_wchar_p as LPWSTR
 
+from ...exceptions import CanInterfaceNotImplementedError
+
 from .constants import *
 from .structures import *
 from .exceptions import *
@@ -110,6 +112,7 @@ def check_result(result, func, arguments):
     return result
 
 
+_UCAN_INITIALIZED = False
 if os.name != "nt":
     log.warning("SYSTEC ucan library does not work on %s platform.", sys.platform)
 else:
@@ -310,6 +313,8 @@ def check_result(result, func, arguments):
         UcanEnableCyclicCanMsg.argtypes = [Handle, BYTE, DWORD]
         UcanEnableCyclicCanMsg.errcheck = check_result
 
+        _UCAN_INITIALIZED = True
+
     except Exception as ex:
         log.warning("Cannot load SYSTEC ucan library: %s.", ex)
 
@@ -323,6 +328,11 @@ class UcanServer:
     _connect_control_ref = None
 
     def __init__(self):
+        if not _UCAN_INITIALIZED:
+            raise CanInterfaceNotImplementedError(
+                "The interface could not be loaded on the current platform"
+            )
+
         self._handle = Handle(INVALID_HANDLE)
         self._is_initialized = False
         self._hw_is_initialized = False