Fix recursion error when getting error descriptions

build/helper.py

@@ -126,6 +126,17 @@ def _add_python_return_type(f):
     f['returns_python'] = f['returns']
     return f
 
+def _add_is_error_handling(f):
+    '''Adds is_error_handling information to the function metadata if it isn't already defined. Defaults to False.'''
+    # TODO(marcoskirsch): The information is added in functions_addon.py. I think we can instead infer from method
+    # name but I am not sure if it's a good idea (heuristics vs being explicit - both error prone in different ways).
+    try:
+        f['is_error_handling']
+    except KeyError:
+        # Not populated, assume False
+        f['is_error_handling'] = False
+    return f
+
 def _add_buffer_info(parameter):
     '''Adds buffer information to the parameter metadata iff 'size' is defined else assume not a buffer'''
     try:
@@ -143,6 +154,7 @@ def add_all_metadata(functions):
         _add_python_method_name(functions[f], f)
         _add_ctypes_return_type(functions[f])
         _add_python_return_type(functions[f])
+        _add_is_error_handling(functions[f])
         for p in functions[f]['parameters']:
             _add_python_parameter_name(p)
             _add_python_type(p)

build/templates/errors.py.mako

@@ -66,18 +66,30 @@ class DriverNotInstalledError(Exception):
         super(DriverNotInstalledError, self).__init__('The ${driver_name} runtime is not installed. Please visit http://www.ni.com/downloads/drivers/ to download and install it.')
 
 
-def handle_error(session, code, ignore_warnings):
+def handle_error(session, code, ignore_warnings, is_error_handling):
+    '''handle_error
+
+    Helper function for handling errors returned by ${module_name}.Library.
+    It calls back into the session to get the corresponding error description
+    and raises if necessary.
+    '''
+
     if _is_success(code) or (_is_warning(code) and ignore_warnings):
         return
-    try:
+
+    if is_error_handling:
+        # The caller is in the midst of error handling. Don't get the
+        # error description in this case as that could itself fail.
+        description = "Failed to retrieve error description."
+        warnings.warn(description)
+    else:
         description = session.get_error_description(code)
-    except Exception as e:
-        # TODO(marcoskirsch): Log this exception.
-        description = ""
-    if (_is_error(code)):
+
+    if _is_error(code):
         raise Error(code, description)
-    if (_is_warning(code)):
-        warnings.warn(${module_name_class}Warning(code, description))
+
+    assert _is_warning(code)
+    warnings.warn(${module_name_class}Warning(code, description))
 
 
 warnings.filterwarnings("always", category=${module_name_class}Warning)

build/templates/session.py.mako

@@ -184,13 +184,18 @@ context_name = 'acquisition' if c['direction'] == 'input' else 'generation'
             _, error_string = self._get_error()
             return error_string
         except errors.Error:
+            pass
+
+        try:
             '''
             It is expected for _get_error to raise when the session is invalid
             (IVI spec requires GetError to fail).
             Use _get_error_message instead. It doesn't require a session.
             '''
             error_string = self._get_error_message(error_code)
             return error_string
+        except errors.Error:
+            return "Failed to retrieve error description."
 
     ''' These are code-generated '''
 % for func_name in sorted(functions):
@@ -216,17 +221,17 @@ context_name = 'acquisition' if c['direction'] == 'input' else 'generation'
 % endfor
 % if ivi_dance_parameter is None:
         error_code = self.library.${c_function_prefix}${func_name}(${helper.get_library_call_parameter_snippet(f['parameters'])})
-        errors.handle_error(self, error_code, ignore_warnings=False)
+        errors.handle_error(self, error_code, ignore_warnings=False, is_error_handling=${f['is_error_handling']})
         ${helper.get_method_return_snippet(f['parameters'])}
 % else:
         ${ivi_dance_size_parameter['python_name']} = 0
         ${ivi_dance_parameter['ctypes_variable_name']} = None
         error_code = self.library.${c_function_prefix}${func_name}(${helper.get_library_call_parameter_snippet(f['parameters'])})
-        errors.handle_error(self, error_code, ignore_warnings=True)
+        errors.handle_error(self, error_code, ignore_warnings=True, is_error_handling=${f['is_error_handling']})
         ${ivi_dance_size_parameter['python_name']} = error_code
         ${ivi_dance_parameter['ctypes_variable_name']} = ctypes.cast(ctypes.create_string_buffer(${ivi_dance_size_parameter['python_name']}), ctypes_types.${ivi_dance_parameter['ctypes_type']})
         error_code = self.library.${c_function_prefix}${func_name}(${helper.get_library_call_parameter_snippet(f['parameters'])})
-        errors.handle_error(self, error_code, ignore_warnings=False)
+        errors.handle_error(self, error_code, ignore_warnings=False, is_error_handling=${f['is_error_handling']})
         ${helper.get_method_return_snippet(f['parameters'])}
 % endif
 % endfor

docs/nidmm/functions.rst

@@ -2086,33 +2086,6 @@ nidmm.Session methods
 
 
 
-.. function:: error_message(error_code, error_message)
-
-    Takes the **Error\_Code** returned by the instrument driver functions,
-    interprets it, and returns it as a user-readable string.
-
-
-
-
-    :param error_code:
-
-
-        The **error\_code** returned from the instrument. The default is 0,
-        indicating VI\_SUCCESS.
-
-
-
-    :type error_code: int
-
-    :rtype: int
-    :return:
-
-
-            The error information formatted into a string.
-
-
-
-
 .. function:: error_query(error_code, error_message)
 
     Reads an **Error\_Code** and message from the DMM error queue. National

docs/niswitch/functions.rst

@@ -1257,36 +1257,6 @@ niswitch.Session methods
 
     :type maximum_time_ms: int
 
-.. function:: error_message(error_code, error_message)
-
-    Converts an error code returned by NI-SWITCH into a user-readable
-    string. Generally this information is supplied in error out of any
-    NI-SWITCH VI. Use :py:func:`niswitch.error_message` for a static lookup of an
-    error code description.
-
-
-
-
-    :param error_code:
-
-
-        Status code returned by any NI-SWITCH function. Default Value: 0
-        (VI\_SUCCESS)
-
-
-
-    :type error_code: int
-
-    :rtype: int
-    :return:
-
-
-            The error information formatted into a string. You must pass a ViChar
-            array with at least 256 bytes.
-
-
-
-
 .. function:: error_query(error_code, error_message)
 
     This function reads an error code and a message from the instrument's

generated/nidmm/errors.py

@@ -57,18 +57,30 @@ def __init__(self):
         super(DriverNotInstalledError, self).__init__('The NI-DMM runtime is not installed. Please visit http://www.ni.com/downloads/drivers/ to download and install it.')
 
 
-def handle_error(session, code, ignore_warnings):
+def handle_error(session, code, ignore_warnings, is_error_handling):
+    '''handle_error
+
+    Helper function for handling errors returned by nidmm.Library.
+    It calls back into the session to get the corresponding error description
+    and raises if necessary.
+    '''
+
     if _is_success(code) or (_is_warning(code) and ignore_warnings):
         return
-    try:
+
+    if is_error_handling:
+        # The caller is in the midst of error handling. Don't get the
+        # error description in this case as that could itself fail.
+        description = "Failed to retrieve error description."
+        warnings.warn(description)
+    else:
         description = session.get_error_description(code)
-    except Exception as e:
-        # TODO(marcoskirsch): Log this exception.
-        description = ""
-    if (_is_error(code)):
+
+    if _is_error(code):
         raise Error(code, description)
-    if (_is_warning(code)):
-        warnings.warn(NidmmWarning(code, description))
+
+    assert _is_warning(code)
+    warnings.warn(NidmmWarning(code, description))
 
 
 warnings.filterwarnings("always", category=NidmmWarning)

generated/nidmm/library.py

@@ -18,7 +18,6 @@ def __init__(self, library_name, library_type):
         self._func_lock = threading.Lock()
         # We cache the cfunc object from the ctypes.CDLL object
         self.niDMM_Abort_cfunc = None
-        self.niDMM_ClearError_cfunc = None
         self.niDMM_ClearInterchangeWarnings_cfunc = None
         self.niDMM_ConfigureACBandwidth_cfunc = None
         self.niDMM_ConfigureADCCalibration_cfunc = None
@@ -92,7 +91,6 @@ def __init__(self, library_name, library_type):
         self.niDMM_SetAttributeViString_cfunc = None
         self.niDMM_UnlockSession_cfunc = None
         self.niDMM_close_cfunc = None
-        self.niDMM_error_message_cfunc = None
         self.niDMM_error_query_cfunc = None
         self.niDMM_reset_cfunc = None
         self.niDMM_revision_query_cfunc = None
@@ -112,14 +110,6 @@ def niDMM_Abort(self, vi):  # noqa: N802
                 self.niDMM_Abort_cfunc.restype = nidmm.python_types.ViStatus
         return self.niDMM_Abort_cfunc(vi)
 
-    def niDMM_ClearError(self, vi):  # noqa: N802
-        with self._func_lock:
-            if self.niDMM_ClearError_cfunc is None:
-                self.niDMM_ClearError_cfunc = self._library.niDMM_ClearError
-                self.niDMM_ClearError_cfunc.argtypes = [ViSession_ctype]  # noqa: F405
-                self.niDMM_ClearError_cfunc.restype = nidmm.python_types.ViStatus
-        return self.niDMM_ClearError_cfunc(vi)
-
     def niDMM_ClearInterchangeWarnings(self, vi):  # noqa: N802
         with self._func_lock:
             if self.niDMM_ClearInterchangeWarnings_cfunc is None:
@@ -484,7 +474,7 @@ def niDMM_GetErrorMessage(self, vi, error_code, buffer_size, error_message):  #
         with self._func_lock:
             if self.niDMM_GetErrorMessage_cfunc is None:
                 self.niDMM_GetErrorMessage_cfunc = self._library.niDMM_GetErrorMessage
-                self.niDMM_GetErrorMessage_cfunc.argtypes = [ViSession_ctype, ViStatus_ctype, ViInt32_ctype, ctypes.POINTER(ViChar_ctype)]  # noqa: F405
+                self.niDMM_GetErrorMessage_cfunc.argtypes = [ViSession_ctype, ViStatus_ctype, ViInt32_ctype, ViString_ctype]  # noqa: F405
                 self.niDMM_GetErrorMessage_cfunc.restype = nidmm.python_types.ViStatus
         return self.niDMM_GetErrorMessage_cfunc(vi, error_code, buffer_size, error_message)
 
@@ -704,14 +694,6 @@ def niDMM_close(self, vi):  # noqa: N802
                 self.niDMM_close_cfunc.restype = nidmm.python_types.ViStatus
         return self.niDMM_close_cfunc(vi)
 
-    def niDMM_error_message(self, vi, error_code, error_message):  # noqa: N802
-        with self._func_lock:
-            if self.niDMM_error_message_cfunc is None:
-                self.niDMM_error_message_cfunc = self._library.niDMM_error_message
-                self.niDMM_error_message_cfunc.argtypes = [ViSession_ctype, ViStatus_ctype, ctypes.POINTER(ViChar_ctype)]  # noqa: F405
-                self.niDMM_error_message_cfunc.restype = nidmm.python_types.ViStatus
-        return self.niDMM_error_message_cfunc(vi, error_code, error_message)
-
     def niDMM_error_query(self, vi, error_code, error_message):  # noqa: N802
         with self._func_lock:
             if self.niDMM_error_query_cfunc is None: