all SNMP counters now incremented via '+= 1' rather than 'x = x + 1'

9 files changed, 22 insertions, 20 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index 2c8153ca..9dc6e354 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -8,6 +8,8 @@ Repository `tarball download <http://pysnmp.cvs.sourceforge.net/viewvc/pysnmp/py
 - SNMP table row consistency check added. This change may break
   valid SNMP SET operations on tables if RowStatus column is not
   passed at the very end of var-binds.
+- All SNMP counters now incremented via '+= 1' rather than 'x = x + 1'
+  to simplify their tracking by third-party code.
 - Fix to snmpInvalidMsgs and snmpUnknownSecurityModels MIB symbols
   import at SNMPv3 MP model.
 
diff --git a/pysnmp/cache.py b/pysnmp/cache.py
index 46ad6020..49be826f 100644
--- a/pysnmp/cache.py
+++ b/pysnmp/cache.py
@@ -19,7 +19,7 @@ class Cache:
         return k in self.__cache
 
     def __getitem__(self, k):
-        self.__usage[k] = self.__usage[k] + 1
+        self.__usage[k] += 1
         return self.__cache[k]
 
     def __len__(self):
@@ -34,7 +34,7 @@ class Cache:
                 del self.__usage[_k]
             self.__size = self.__size - self.__chopSize
         if k not in self.__cache:
-            self.__size = self.__size + 1
+            self.__size += 1
             self.__usage[k] = 0
         self.__cache[k] = v
 
diff --git a/pysnmp/carrier/asyncio/dispatch.py b/pysnmp/carrier/asyncio/dispatch.py
index 4365f792..0955fac5 100644
--- a/pysnmp/carrier/asyncio/dispatch.py
+++ b/pysnmp/carrier/asyncio/dispatch.py
@@ -71,13 +71,13 @@ class AsyncioDispatcher(AbstractTransportDispatcher):
         AbstractTransportDispatcher.registerTransport(
             self, tDomain, transport
             )
-        self.__transportCount = self.__transportCount + 1
+        self.__transportCount += 1
 
     def unregisterTransport(self, tDomain):
         t = AbstractTransportDispatcher.getTransport(self, tDomain)
         if t is not None:
             AbstractTransportDispatcher.unregisterTransport(self, tDomain)
-            self.__transportCount = self.__transportCount - 1
+            self.__transportCount -= 1
 
         # The last transport has been removed, stop the timeout
         if self.__transportCount == 0 and not self.loopingcall.done():
diff --git a/pysnmp/entity/engine.py b/pysnmp/entity/engine.py
index a3036fd0..cce2503b 100644
--- a/pysnmp/entity/engine.py
+++ b/pysnmp/entity/engine.py
@@ -119,7 +119,7 @@ class SnmpEngine:
                 pass
 
             try:
-                snmpEngineBoots.syntax = snmpEngineBoots.syntax + 1
+                snmpEngineBoots.syntax += 1
             except:
                 snmpEngineBoots.syntax = snmpEngineBoots.syntax.clone(1)
 
diff --git a/pysnmp/entity/rfc3413/ntfrcv.py b/pysnmp/entity/rfc3413/ntfrcv.py
index 1a27222c..da3734e5 100644
--- a/pysnmp/entity/rfc3413/ntfrcv.py
+++ b/pysnmp/entity/rfc3413/ntfrcv.py
@@ -78,7 +78,7 @@ class NotificationReceiver:
             except error.StatusInformation:
                 debug.logger & debug.flagApp and debug.logger('processPdu: stateReference %s, statusInformation %s' % (stateReference, sys.exc_info()[1]))
                 snmpSilentDrops, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMPv2-MIB', 'snmpSilentDrops')
-                snmpSilentDrops.syntax = snmpSilentDrops.syntax + 1
+                snmpSilentDrops.syntax += 1
 
         elif PDU.tagSet in rfc3411.unconfirmedClassPDUs:
             pass
diff --git a/pysnmp/proto/mpmod/rfc2576.py b/pysnmp/proto/mpmod/rfc2576.py
index 605d01ca..ebe6e43c 100644
--- a/pysnmp/proto/mpmod/rfc2576.py
+++ b/pysnmp/proto/mpmod/rfc2576.py
@@ -238,7 +238,7 @@ class SnmpV1MessageProcessingModel(AbstractMessageProcessingModel):
         except PyAsn1Error:
             debug.logger & debug.flagMP and debug.logger('prepareDataElements: %s' % (sys.exc_info()[1],))
             snmpInASNParseErrs, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMPv2-MIB', 'snmpInASNParseErrs')
-            snmpInASNParseErrs.syntax = snmpInASNParseErrs.syntax + 1
+            snmpInASNParseErrs.syntax += 1
             raise error.StatusInformation(errorIndication=errind.parseError)
 
         debug.logger & debug.flagMP and debug.logger('prepareDataElements: %s' % (msg.prettyPrint(),))
diff --git a/pysnmp/proto/rfc3412.py b/pysnmp/proto/rfc3412.py
index 26052c68..99117d3d 100644
--- a/pysnmp/proto/rfc3412.py
+++ b/pysnmp/proto/rfc3412.py
@@ -280,7 +280,7 @@ class MsgAndPduDispatcher:
             msgVersion = verdec.decodeMessageVersion(wholeMsg)
         except error.ProtocolError:
             snmpInASNParseErrs, = self.mibInstrumController.mibBuilder.importSymbols('__SNMPv2-MIB', 'snmpInASNParseErrs')
-            snmpInASNParseErrs.syntax = snmpInASNParseErrs.syntax + 1
+            snmpInASNParseErrs.syntax += 1
             return null  # n.b the whole buffer gets dropped
 
         debug.logger & debug.flagDsp and debug.logger('receiveMessage: msgVersion %s, msg decoded' % msgVersion)
@@ -292,7 +292,7 @@ class MsgAndPduDispatcher:
             mpHandler = snmpEngine.messageProcessingSubsystems[k]
         else:
             snmpInBadVersions, = self.mibInstrumController.mibBuilder.importSymbols('__SNMPv2-MIB', 'snmpInBadVersions')
-            snmpInBadVersions.syntax = snmpInBadVersions.syntax + 1
+            snmpInBadVersions.syntax += 1
             return restOfWholeMsg
 
         # 4.2.1.3 -- no-op
@@ -337,7 +337,7 @@ class MsgAndPduDispatcher:
             if processPdu is None:
                 # 4.2.2.1.2.a
                 snmpUnknownPDUHandlers, = self.mibInstrumController.mibBuilder.importSymbols('__SNMP-MPD-MIB', 'snmpUnknownPDUHandlers')
-                snmpUnknownPDUHandlers.syntax = snmpUnknownPDUHandlers.syntax+1
+                snmpUnknownPDUHandlers.syntax += 1
 
                 # 4.2.2.1.2.b
                 statusInformation = {
@@ -425,7 +425,7 @@ class MsgAndPduDispatcher:
             # 4.2.2.2.2
             if cachedParams is None:
                 snmpUnknownPDUHandlers, = self.mibInstrumController.mibBuilder.importSymbols('__SNMP-MPD-MIB', 'snmpUnknownPDUHandlers')
-                snmpUnknownPDUHandlers.syntax = snmpUnknownPDUHandlers.syntax+1
+                snmpUnknownPDUHandlers.syntax += 1
                 return restOfWholeMsg
 
             debug.logger & debug.flagDsp and debug.logger('receiveMessage: cache read by sendPduHandle %s' % sendPduHandle)
diff --git a/pysnmp/proto/secmod/rfc2576.py b/pysnmp/proto/secmod/rfc2576.py
index 1aa8cded..337153f3 100644
--- a/pysnmp/proto/secmod/rfc2576.py
+++ b/pysnmp/proto/secmod/rfc2576.py
@@ -332,7 +332,7 @@ class SnmpV1SecurityModel(base.AbstractSecurityModel):
 
         except error.StatusInformation:
             snmpInBadCommunityNames, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMPv2-MIB', 'snmpInBadCommunityNames')
-            snmpInBadCommunityNames.syntax = snmpInBadCommunityNames.syntax+1
+            snmpInBadCommunityNames.syntax += 1
             raise error.StatusInformation(errorIndication=errind.unknownCommunityName)
 
         snmpEngineID, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMP-FRAMEWORK-MIB', 'snmpEngineID')
diff --git a/pysnmp/proto/secmod/rfc3414/service.py b/pysnmp/proto/secmod/rfc3414/service.py
index cc3edf73..7bb0e54d 100644
--- a/pysnmp/proto/secmod/rfc3414/service.py
+++ b/pysnmp/proto/secmod/rfc3414/service.py
@@ -265,7 +265,7 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
             except PyAsn1Error:
                 debug.logger & debug.flagSM and debug.logger('processIncomingMsg: %s' % (sys.exc_info()[1],))
                 snmpInGenErrs, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMPv2-MIB', 'snmpInGenErrs')
-                snmpInGenErrs.syntax = snmpInGenErrs.syntax + 1
+                snmpInGenErrs.syntax += 1
                 raise error.StatusInformation(
                     errorIndication=errind.invalidMsg
                 )
@@ -532,7 +532,7 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
                     not 4 < len(msgAuthoritativeEngineID) < 33:
                 # 3.2.3b
                 usmStatsUnknownEngineIDs, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMP-USER-BASED-SM-MIB', 'usmStatsUnknownEngineIDs')
-                usmStatsUnknownEngineIDs.syntax = usmStatsUnknownEngineIDs.syntax+1
+                usmStatsUnknownEngineIDs.syntax += 1
                 debug.logger & debug.flagSM and debug.logger('processIncomingMsg: null or malformed msgAuthoritativeEngineID')
                 pysnmpUsmDiscoverable, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__PYSNMP-USM-MIB', 'pysnmpUsmDiscoverable')
                 if pysnmpUsmDiscoverable.syntax:
@@ -620,7 +620,7 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
             except PyAsn1Error:
                 debug.logger & debug.flagSM and debug.logger('processIncomingMsg: %s' % (sys.exc_info()[1],))
                 snmpInGenErrs, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMPv2-MIB', 'snmpInGenErrs')
-                snmpInGenErrs.syntax = snmpInGenErrs.syntax + 1
+                snmpInGenErrs.syntax += 1
                 raise error.StatusInformation(errorIndication=errind.invalidMsg)
         else:
             # empty username used for engineID discovery
@@ -669,7 +669,7 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
                     __badSecIndication = 'noAuthNoPriv wanted while priv expected'
             if __badSecIndication:
                 usmStatsUnsupportedSecLevels, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMP-USER-BASED-SM-MIB', 'usmStatsUnsupportedSecLevels')
-                usmStatsUnsupportedSecLevels.syntax = usmStatsUnsupportedSecLevels.syntax + 1
+                usmStatsUnsupportedSecLevels.syntax += 1
                 debug.logger & debug.flagSM and debug.logger('processIncomingMsg: reporting inappropriate security level for user %s: %s' % (msgUserName, __badSecIndication))
                 raise error.StatusInformation(
                     errorIndication=errind.unsupportedSecurityLevel,
@@ -700,7 +700,7 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
 
             except error.StatusInformation:
                 usmStatsWrongDigests, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMP-USER-BASED-SM-MIB', 'usmStatsWrongDigests')
-                usmStatsWrongDigests.syntax = usmStatsWrongDigests.syntax+1
+                usmStatsWrongDigests.syntax += 1
                 raise error.StatusInformation(
                     errorIndication=errind.authenticationFailure,
                     oid=usmStatsWrongDigests.name,
@@ -760,7 +760,7 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
                    abs(idleTime + int(snmpEngineTime) - \
                        int(msgAuthoritativeEngineTime)) > 150:
                     usmStatsNotInTimeWindows, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMP-USER-BASED-SM-MIB', 'usmStatsNotInTimeWindows')
-                    usmStatsNotInTimeWindows.syntax = usmStatsNotInTimeWindows.syntax+1
+                    usmStatsNotInTimeWindows.syntax += 1
                     raise error.StatusInformation(
                         errorIndication=errind.notInTimeWindow,
                         oid=usmStatsNotInTimeWindows.name,
@@ -826,7 +826,7 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
 
             except error.StatusInformation:
                 usmStatsDecryptionErrors, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMP-USER-BASED-SM-MIB', 'usmStatsDecryptionErrors')
-                usmStatsDecryptionErrors.syntax = usmStatsDecryptionErrors.syntax+1
+                usmStatsDecryptionErrors.syntax += 1
                 raise error.StatusInformation(
                     errorIndication=errind.decryptionError,
                     oid=usmStatsDecryptionErrors.name,
@@ -870,7 +870,7 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
         # Delayed to include details
         if not msgUserName and not msgAuthoritativeEngineID:
             usmStatsUnknownUserNames, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMP-USER-BASED-SM-MIB', 'usmStatsUnknownUserNames')
-            usmStatsUnknownUserNames.syntax = usmStatsUnknownUserNames.syntax+1
+            usmStatsUnknownUserNames.syntax += 1
             raise error.StatusInformation(
                 errorIndication=errind.unknownSecurityName,
                 oid=usmStatsUnknownUserNames.name,