fix issues raising pylint warnings

+ small bug fixes

Change-Id: Ib63bf13ad06446d3ec3b8cd0b16f9426cef9e3f4

secop/client/__init__.py

@@ -517,7 +517,7 @@ class SecopClient(ProxyClient):
             raise ConnectionError('connection closed before reply')
         action, _, data = entry[2]  # pylint: disable=unpacking-non-sequence
         if action.startswith(ERRORPREFIX):
-            errcls = self.error_map(data[0] + "Error")
+            errcls = self.error_map(data[0])
             raise errcls(data[1])
         return entry[2]  # reply
 

secop/datatypes.py

@@ -194,7 +194,7 @@ class FloatRange(DataType):
         try:
             value = float(value)
         except Exception:
-            raise BadValueError('Can not __call__ %r to float' % value)
+            raise BadValueError('Can not convert %r to float' % value)
         # map +/-infty to +/-max possible number
         value = clamp(-sys.float_info.max, value, sys.float_info.max)
 

secop/errors.py

@@ -143,7 +143,7 @@ EXCEPTIONS = dict(
     NoSuchCommand=NoSuchCommandError,
     CommandFailed=CommandFailedError,
     CommandRunning=CommandRunningError,
-    Readonly=ReadOnlyError,
+    ReadOnly=ReadOnlyError,
     BadValue=BadValueError,
     CommunicationFailed=CommunicationFailedError,
     HardwareError=HardwareError,

secop/params.py

@@ -149,9 +149,6 @@ class Parameter(Accessible):
     handler = Property(
         '[internal] overload the standard read and write functions', ValueType(),
         export=False, default=None, settable=False)
-    persistent = Property(
-        '[internal] persistent setting', BoolType(),
-        export=False, default=False)
     initwrite = Property(
         '''[internal] write this parameter on initialization
 

secop/properties.py

@@ -134,7 +134,7 @@ class HasProperties(HasDescriptors):
     propertyValues = None
 
     def __init__(self):
-        super(HasProperties, self).__init__()
+        super().__init__()
         # store property values in the instance, keep descriptors on the class
         self.propertyValues = {}
         # pre-init
@@ -168,9 +168,9 @@ class HasProperties(HasDescriptors):
                         if pn in getattr(base, 'propertyDict', {}):
                             if callable(value):
                                 raise ProgrammingError('method %s.%s collides with property of %s' %
-                                                       (cls.__name__, pn, base.__name__))
+                                                       (cls.__name__, pn, base.__name__)) from None
                             raise ProgrammingError('can not set property %s.%s to %r' %
-                                                   (cls.__name__, pn, value))
+                                                   (cls.__name__, pn, value)) from None
                 cls.propertyDict[pn] = po
 
     def checkProperties(self):
@@ -181,7 +181,7 @@ class HasProperties(HasDescriptors):
                     self.propertyValues[pn] = po.datatype(self.propertyValues[pn])
                 except (KeyError, BadValueError):
                     name = getattr(self, 'name', self.__class__.__name__)
-                    raise ConfigError('%s.%s needs a value of type %r!' % (name, pn, po.datatype))
+                    raise ConfigError('%s.%s needs a value of type %r!' % (name, pn, po.datatype)) from None
         for pn, po in self.propertyDict.items():
             if pn.startswith('min'):
                 maxname = 'max' + pn[3:]

secop/protocol/interface/tcp.py

@@ -26,6 +26,7 @@ import socketserver
 import sys
 import threading
 import time
+import errno
 
 from secop.datatypes import BoolType, StringType
 from secop.errors import SECoPError
@@ -192,9 +193,9 @@ class TCPServer(socketserver.ThreadingTCPServer):
                     self, ('0.0.0.0', port), TCPRequestHandler, bind_and_activate=True)
                 break
             except OSError as e:
-                if e.args[0] == 98:  # address already in use
+                if e.args[0] == errno.EADDRINUSE:  # address already in use
                     # this may happen despite of allow_reuse_address
-                    time.sleep(0.3 * (1 << ntry))
+                    time.sleep(0.3 * (1 << ntry))  # max accumulated sleep time: 0.3 * 31 = 9.3 sec
                 else:
                     self.log.error('could not initialize TCP Server: %r' % e)
                     raise