update CI workflows: update/fix codecheck; remove Ubuntu 18.04 (#1167)

1. update/fix codecheck

Run workflow with pylint 2.15.7

Add a  bunch of fiddly and mostly cosmetic changes to
make pylint (and make codecheck) happy.

Also try to run pyflakes3 vs. pyflakes

2. remove Ubuntu 18.04

Ubuntu 18.04 has been removed from github actions, so
we remove it from our workflow as well

.github/workflows/code-check.yaml

@@ -17,6 +17,6 @@ jobs:
       - name: Install Mininet code check dependencies
         run: |
           PYTHON=`which python` util/install.sh -n
-          python -m pip install pylint==2.4.4
+          python -m pip install pylint==2.15.7
       - name: Run code check
         run:  make codecheck

.github/workflows/run-tests.yaml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-20.04, ubuntu-18.04]
+        os: [ubuntu-20.04]
         python-version: [3.x, 2.x]
     steps:
       - name: Check out Mininet source

.pylint

@@ -16,7 +16,7 @@
 #init-hook=
 
 # Profiled execution.
-profile=no
+#profile=no
 
 # Add <file or directory> to the black list. It should be a base name, not a
 # path. You may set this option multiple times.
@@ -45,12 +45,13 @@ load-plugins=
 # Note: we may want to re-enable some of these at some point, but many of them
 # are just style issues rather than errors.
 #
-disable=pointless-except, invalid-name, super-init-not-called, fixme, star-args,
+disable=invalid-name, super-init-not-called, fixme,
         too-many-instance-attributes, too-few-public-methods,
-        too-many-locals, too-many-public-methods, duplicate-code, bad-whitespace,
+        too-many-locals, too-many-public-methods, duplicate-code,
-        locally-disabled, locally-enabled, bad-continuation,
+        locally-disabled,
         useless-object-inheritance, unnecessary-pass, no-else-return,
-        no-else-raise, no-else-continue, super-with-arguments
+        no-else-raise, no-else-continue, super-with-arguments,
+        consider-using-f-string, unspecified-encoding
 
 # bad-continuation, wrong-import-order
 
@@ -62,12 +63,12 @@ output-format=colorized
 msg-template='{path}:{line}: [{msg_id}({symbol}), {obj}] {msg}'
 
 # Include message's id in output
-include-ids=yes
+# include-ids=yes
 
 # Put messages in a separate file for each module / package specified on the
 # command line instead of printing them on stdout. Reports (if any) will be
 # written in a file name "pylint_global.[txt|html]".
-files-output=no
+# files-output=no
 
 # Tells whether to display a full report or only the messages
 reports=no
@@ -81,7 +82,7 @@ evaluation=10.0 - ((float(5 * error + warning + refactor + convention) / stateme
 
 # Add a comment according to your evaluation note. This is used by the global
 # evaluation report (R0004).
-comment=no
+#comment=no
 
 # Enable the report(s) with the given id(s).
 #enable-report=
@@ -103,7 +104,7 @@ comment=no
 [BASIC]
 
 # Required attributes for module, separated by a comma
-required-attributes=
+#required-attributes=
 
 # Regular expression which should only match functions or classes name which do
 # not require a docstring
@@ -144,7 +145,7 @@ good-names=i,j,k,ex,Run,_
 bad-names=foo,bar,baz,toto,tutu,tata
 
 # List of builtins function names that should not be used, separated by a comma
-bad-functions=map,filter,apply,inpu
+#bad-functions=map,filter,apply,inpu
 
 
 # try to find bugs in the code using type inference
@@ -161,7 +162,7 @@ ignored-classes=SQLObjec
 
 # When zope mode is activated, add a predefined set of Zope acquired attributes
 # to generated-members.
-zope=no
+#zope=no
 
 # List of members which are set dynamically and missed by pylint inference
 # system, and so shouldn't trigger E0201 when accessed.
@@ -199,7 +200,7 @@ additional-builtins=
 
 # List of interface methods to ignore, separated by a comma. This is used for
 # instance to not check methods defines in Zope's Interface base class.
-ignore-iface-methods=isImplementedBy,deferred,extends,names,namesAndDescriptions,queryDescriptionFor,getBases,getDescriptionFor,getDoc,getName,getTaggedValue,getTaggedValueTags,isEqualOrExtendedBy,setTaggedValue,isImplementedByInstancesOf,adaptWith,is_implemented_by
+#ignore-iface-methods=isImplementedBy,deferred,extends,names,namesAndDescriptions,queryDescriptionFor,getBases,getDescriptionFor,getDoc,getName,getTaggedValue,getTaggedValueTags,isEqualOrExtendedBy,setTaggedValue,isImplementedByInstancesOf,adaptWith,is_implemented_by
 
 # List of method names used to declare (i.e. assign) instance attributes.
 defining-attr-methods=__init__,__new__,setUp,build
@@ -221,7 +222,7 @@ max-locals=15
 max-returns=6
 
 # Maximum number of branch for function / method body
-max-branchs=12
+#max-branchs=12
 
 # Maximum number of statements in function / method body
 max-statements=50

Makefile

@@ -26,14 +26,14 @@ clean:
 codecheck: $(PYSRC)
 	-echo "Running code check"
 	util/versioncheck.py
-	pyflakes $(PYSRC)
+	pyflakes3 $(PYSRC) || pyflakes $(PYSRC)
 	pylint --rcfile=.pylint $(PYSRC)
 #	Exclude miniedit from pep8 checking for now
 	pep8 --repeat --ignore=$(P8IGN) `ls $(PYSRC) | grep -v miniedit.py`
 
 errcheck: $(PYSRC)
 	-echo "Running check for errors only"
-	pyflakes $(PYSRC)
+	pyflakes3 $(PYSRC) || pyflakes $(PYSRC)
 	pylint -E --rcfile=.pylint $(PYSRC)
 
 test: $(MININET) $(TEST)

bin/mn

@@ -189,7 +189,8 @@ class MininetRunner( object ):
             customs = {}
             if os.path.isfile( fileName ):
                 # pylint: disable=exec-used
-                exec( compile( open( fileName ).read(), fileName, 'exec' ),
+                with open( fileName ) as f:
+                    exec( compile( f.read(), fileName, 'exec' ),
                           customs, customs )
                 for name, val in customs.items():
                     self.setCustom( name, val )

examples/baresshd.py

@@ -27,9 +27,8 @@ h1.setIP( '10.0.0.1', 8 )
 root.setIP( '10.0.0.2', 8 )
 
 info( "*** Creating banner file\n" )
-f = open( '/tmp/%s.banner' % h1.name, 'w' )
+with open( '/tmp/%s.banner' % h1.name, 'w' ) as f:
-f.write( 'Welcome to %s at %s\n' % ( h1.name, h1.IP() ) )
+    f.write( 'Welcome to %s at %s\n' % ( h1.name, h1.IP() ) )
-f.close()
 
 info( "*** Running sshd\n" )
 cmd = '/usr/sbin/sshd -o UseDNS=no -u0 -o "Banner /tmp/%s.banner"' % h1.name

examples/cluster.py

@@ -82,14 +82,13 @@ import sys
 import re
 from itertools import groupby
 from operator import attrgetter
-from distutils.version import StrictVersion
 
 from mininet.node import Node, Host, OVSSwitch, Controller
 from mininet.link import Link, Intf
 from mininet.net import Mininet
 from mininet.topo import LinearTopo
 from mininet.topolib import TreeTopo
-from mininet.util import quietRun, errRun, decode
+from mininet.util import quietRun, errRun, decode, StrictVersion
 from mininet.examples.clustercli import CLI
 from mininet.log import setLogLevel, debug, info, error
 from mininet.clean import addCleanupCallback
@@ -314,7 +313,7 @@ class RemoteOVSSwitch( RemoteMixin, OVSSwitch ):
         kwargs.update( batch=True )
         super( RemoteOVSSwitch, self ).__init__( *args, **kwargs )
 
-    def isOldOVS( self ):
+    def isOldOVS( self ):  # pylint: disable=arguments-differ
         "Is remote switch using an old OVS version?"
         cls = type( self )
         if self.server not in cls.OVSVersions:
@@ -376,7 +375,8 @@ class RemoteLink( Link ):
             Link.stop( self )
         self.tunnel = None
 
-    def makeIntfPair( self, intfname1, intfname2, addr1=None, addr2=None,
+    def makeIntfPair( self,  # pylint: disable=arguments-renamed
+                      intfname1, intfname2, addr1=None, addr2=None,
                       node1=None, node2=None, deleteIntfs=True ):
         """Create pair of interfaces
             intfname1: name of interface 1
@@ -781,7 +781,9 @@ class MininetCluster( Mininet ):
         "Popen() for server connections"
         assert self  # please pylint
         old = signal( SIGINT, SIG_IGN )
+        # pylint: disable=consider-using-with
         conn = Popen( cmd, stdin=PIPE, stdout=PIPE, close_fds=True )
+        # pylint: enable=consider-using-with
         signal( SIGINT, old )
         return conn
 

examples/consoles.py

@@ -69,7 +69,10 @@ class Console( Frame ):
         self.bindEvents()
         self.sendCmd( 'export TERM=dumb' )
 
-        self.outputHook = None
+        def outputHook( _obj, _text):
+            return True
+
+        self.outputHook = outputHook
 
     def makeWidgets( self ):
         "Make a label, a text area, and a scroll bar."
@@ -111,10 +114,8 @@ class Console( Frame ):
         self.text.insert( 'end', text )
         self.text.mark_set( 'insert', 'end' )
         self.text.see( 'insert' )
-        outputHook = lambda x, y: True  # make pylint happier
+        if callable( self.outputHook ):
-        if self.outputHook:
+            self.outputHook( self, text )
-            outputHook = self.outputHook
-        outputHook( self, text )
 
     def handleKey( self, event ):
         "If it's an interactive command, send it to the node."
@@ -294,10 +295,10 @@ class ConsoleApp( Frame ):
             'switches': 'Switch',
             'controllers': 'Controller'
         }
-        for name in titles:
+        for name, title in titles.items():
             nodes = getattr( net, name )
             frame, consoles = self.createConsoles(
-                cframe, nodes, width, titles[ name ] )
+                cframe, nodes, width, title )
             self.consoles[ name ] = Object( frame=frame, consoles=consoles )
         self.selected = None
         self.select( 'hosts' )

examples/linearbandwidth.py

@@ -83,9 +83,8 @@ def linearBandwidthTest( lengths ):
     output = quietRun( 'sysctl -w net.ipv4.tcp_congestion_control=reno' )
     assert 'reno' in output
 
-    for datapath in switches:
+    for datapath, Switch in switches.items():
         info( "*** testing", datapath, "datapath\n" )
-        Switch = switches[ datapath ]
         results[ datapath ] = []
         link = partial( TCLink, delay='30ms', bw=100 )
         net = Mininet( topo=topo, switch=Switch,

examples/miniedit.py

@@ -18,16 +18,15 @@ import os
 import re
 import sys
 
-from distutils.version import StrictVersion
 from functools import partial
-from optparse import OptionParser
+from optparse import OptionParser  # pylint: disable=deprecated-module
 from subprocess import call
 from sys import exit  # pylint: disable=redefined-builtin
 
 from mininet.log import info, debug, warn, setLogLevel
 from mininet.net import Mininet, VERSION
 from mininet.util import (netParse, ipAdd, quietRun,
-                          buildTopo, custom, customClass )
+                          buildTopo, custom, customClass, StrictVersion )
 from mininet.term import makeTerm, cleanUpScreens
 from mininet.node import (Controller, RemoteController, NOX, OVSController,
                           CPULimitedHost, Host, Node,
@@ -1363,7 +1362,7 @@ class MiniEdit( Frame ):
 
         # Tools
         for tool in self.tools:
-            cmd = ( lambda t=tool: self.activate( t ) )
+            cmd = partial( self.activate, tool )
             b = Button( toolbar, text=tool, font=self.smallFont, command=cmd)
             if tool in self.images:
                 b.config( height=35, image=self.images[ tool ] )
@@ -1421,10 +1420,7 @@ class MiniEdit( Frame ):
 
     def convertJsonUnicode(self, text):
         "Some part of Mininet don't like Unicode"
-        try:
+        unicode = globals.get( 'unicode', str )
-            unicode
-        except NameError:
-            return text
         if isinstance(text, dict):
             return {self.convertJsonUnicode(key): self.convertJsonUnicode(value) for key, value in text.items()}
         if isinstance(text, list):
@@ -1635,10 +1631,10 @@ class MiniEdit( Frame ):
             hostsToSave = []
             switchesToSave = []
             controllersToSave = []
-            for widget in self.widgetToItem:
+            for widget, item in self.widgetToItem.items():
                 name = widget[ 'text' ]
-                tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                tags = self.canvas.gettags( item )
-                x1, y1 = self.canvas.coords( self.widgetToItem[ widget ] )
+                x1, y1 = self.canvas.coords( item )
                 if 'Switch' in tags or 'LegacySwitch' in tags or 'LegacyRouter' in tags:
                     nodeNum = self.switchOpts[name]['nodeNum']
                     nodeToSave = {'number':str(nodeNum),
@@ -1683,14 +1679,13 @@ class MiniEdit( Frame ):
             savingDictionary['application'] = self.appPrefs
 
             try:
-                f = open(fileName, 'w')
+                with open(fileName, 'w') as f:
-                f.write(json.dumps(savingDictionary, sort_keys=True, indent=4, separators=(',', ': ')))
+                    f.write(
-            # pylint: disable=broad-except
+                        json.dumps(savingDictionary,
-            except Exception as er:
+                                   sort_keys=True,
+                                   indent=4, separators=(',', ': ')))
+            except Exception as er:  # pylint: disable=broad-except
                 warn( er, '\n' )
-            # pylint: enable=broad-except
-            finally:
-                f.close()
 
     def exportScript( self ):
         "Export command."
@@ -1702,7 +1697,7 @@ class MiniEdit( Frame ):
         fileName = tkFileDialog.asksaveasfilename(filetypes=myFormats ,title="Export the topology as...")
         if len(fileName ) > 0:
             # debug( "Now saving under %s\n" % fileName )
-            f = open(fileName, 'w')
+            f = open(fileName, 'w')  # pylint: disable=consider-using-with
 
             f.write("#!/usr/bin/env python\n")
             f.write("\n")
@@ -1718,9 +1713,9 @@ class MiniEdit( Frame ):
             f.write("from subprocess import call\n")
 
             inBandCtrl = False
-            for widget in self.widgetToItem:
+            for widget, item in self.widgetToItem.items():
                 name = widget[ 'text' ]
-                tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                tags = self.canvas.gettags( item )
 
                 if 'Controller' in tags:
                     opts = self.controllers[name]
@@ -1746,9 +1741,9 @@ class MiniEdit( Frame ):
             f.write("                   ipBase='"+self.appPrefs['ipBase']+"')\n")
             f.write("\n")
             f.write("    info( '*** Adding controller\\n' )\n")
-            for widget in self.widgetToItem:
+            for widget, item in self.widgetToItem.items():
                 name = widget[ 'text' ]
-                tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                tags = self.canvas.gettags( item )
 
                 if 'Controller' in tags:
                     opts = self.controllers[name]
@@ -1780,9 +1775,9 @@ class MiniEdit( Frame ):
 
             # Save Switches and Hosts
             f.write("    info( '*** Add switches\\n')\n")
-            for widget in self.widgetToItem:
+            for widget, item in self.widgetToItem.items():
                 name = widget[ 'text' ]
-                tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                tags = self.canvas.gettags( item )
                 if 'LegacyRouter' in tags:
                     f.write("    "+name+" = net.addHost('"+name+"', cls=Node, ip='0.0.0.0')\n")
                     f.write("    "+name+".cmd('sysctl -w net.ipv4.ip_forward=1')\n")
@@ -1820,9 +1815,9 @@ class MiniEdit( Frame ):
 
             f.write("\n")
             f.write("    info( '*** Add hosts\\n')\n")
-            for widget in self.widgetToItem:
+            for widget, item in self.widgetToItem.items():
                 name = widget[ 'text' ]
-                tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                tags = self.canvas.gettags( item )
                 if 'Host' in tags:
                     opts = self.hostOpts[name]
                     ip = None
@@ -1915,9 +1910,9 @@ class MiniEdit( Frame ):
             f.write("\n")
 
             f.write("    info( '*** Starting switches\\n')\n")
-            for widget in self.widgetToItem:
+            for widget, item in self.widgetToItem.items():
                 name = widget[ 'text' ]
-                tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                tags = self.canvas.gettags( item )
                 if 'Switch' in tags or 'LegacySwitch' in tags:
                     opts = self.switchOpts[name]
                     ctrlList = ",".join(opts['controllers'])
@@ -1926,9 +1921,9 @@ class MiniEdit( Frame ):
             f.write("\n")
 
             f.write("    info( '*** Post configure switches and hosts\\n')\n")
-            for widget in self.widgetToItem:
+            for widget, item in self.widgetToItem.items():
                 name = widget[ 'text' ]
-                tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                tags = self.canvas.gettags( item )
                 if 'Switch' in tags:
                     opts = self.switchOpts[name]
                     if opts['switchType'] == 'default':
@@ -1956,9 +1951,9 @@ class MiniEdit( Frame ):
                         if 'switchIP' in opts:
                             if len(opts['switchIP']) > 0:
                                 f.write("    "+name+".cmd('ifconfig "+name+" "+opts['switchIP']+"')\n")
-            for widget in self.widgetToItem:
+            for widget, item in self.widgetToItem.items():
                 name = widget[ 'text' ]
-                tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                tags = self.canvas.gettags( item )
                 if 'Host' in tags:
                     opts = self.hostOpts[name]
                     # Attach vlan interfaces
@@ -1980,9 +1975,9 @@ class MiniEdit( Frame ):
             if len(nflowValues['nflowTarget']) > 0:
                 nflowEnabled = False
                 nflowSwitches = ''
-                for widget in self.widgetToItem:
+                for widget, item in self.widgetToItem.items():
                     name = widget[ 'text' ]
-                    tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                    tags = self.canvas.gettags( item )
 
                     if 'Switch' in tags:
                         opts = self.switchOpts[name]
@@ -2004,9 +1999,9 @@ class MiniEdit( Frame ):
             if len(sflowValues['sflowTarget']) > 0:
                 sflowEnabled = False
                 sflowSwitches = ''
-                for widget in self.widgetToItem:
+                for widget, item in self.widgetToItem.items():
                     name = widget[ 'text' ]
-                    tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                    tags = self.canvas.gettags( item )
 
                     if 'Switch' in tags:
                         opts = self.switchOpts[name]
@@ -2021,9 +2016,9 @@ class MiniEdit( Frame ):
 
             f.write("\n")
             f.write("    CLI(net)\n")
-            for widget in self.widgetToItem:
+            for widget, item in self.widgetToItem:
                 name = widget[ 'text' ]
-                tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                tags = self.canvas.gettags( item )
                 if 'Host' in tags:
                     opts = self.hostOpts[name]
                     # Run User Defined Stop Command
@@ -2445,7 +2440,8 @@ class MiniEdit( Frame ):
             line3.pack(pady=10 )
             line4.pack(pady=10 )
             line5.pack(pady=10 )
-            hide = ( lambda about=about: about.withdraw() )
+            def hide():
+                about.withdraw()
             self.aboutBox = about
             # Hide on close rather than destroying window
             Wm.wm_protocol( about, name='WM_DELETE_WINDOW', func=hide )
@@ -2620,9 +2616,9 @@ class MiniEdit( Frame ):
             info( 'New controller details for ' + name + ' = ' + str(self.controllers[name]), '\n' )
             # Find references to controller and change name
             if oldName != name:
-                for widget in self.widgetToItem:
+                for widget, item in self.widgetToItem.items():
                     switchName = widget[ 'text' ]
-                    tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                    tags = self.canvas.gettags( item )
                     if 'Switch' in tags:
                         switch = self.switchOpts[switchName]
                         if oldName in switch['controllers']:
@@ -2703,9 +2699,9 @@ class MiniEdit( Frame ):
         tags = self.canvas.gettags(item)
         if 'Controller' in tags:
             # remove from switch controller lists
-            for searchwidget in self.widgetToItem:
+            for searchwidget, searchitem in self.widgetToItem.items():
                 name = searchwidget[ 'text' ]
-                tags = self.canvas.gettags( self.widgetToItem[ searchwidget ] )
+                tags = self.canvas.gettags( searchitem )
                 if 'Switch' in tags:
                     if widget['text'] in self.switchOpts[name]['controllers']:
                         self.switchOpts[name]['controllers'].remove(widget['text'])
@@ -2718,9 +2714,9 @@ class MiniEdit( Frame ):
     def buildNodes( self, net):
         # Make nodes
         info( "Getting Hosts and Switches.\n" )
-        for widget in self.widgetToItem:
+        for widget, item in self.widgetToItem.items():
             name = widget[ 'text' ]
-            tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+            tags = self.canvas.gettags( item )
             # debug( name+' has '+str(tags), '\n' )
 
             if 'Switch' in tags:
@@ -2934,9 +2930,9 @@ class MiniEdit( Frame ):
     def postStartSetup( self ):
 
         # Setup host details
-        for widget in self.widgetToItem:
+        for widget, item in self.widgetToItem.items():
             name = widget[ 'text' ]
-            tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+            tags = self.canvas.gettags( item )
             if 'Host' in tags:
                 newHost = self.net.get(name)
                 opts = self.hostOpts[name]
@@ -2961,9 +2957,9 @@ class MiniEdit( Frame ):
         if len(nflowValues['nflowTarget']) > 0:
             nflowEnabled = False
             nflowSwitches = ''
-            for widget in self.widgetToItem:
+            for widget, item in self.widgetToItem.items():
                 name = widget[ 'text' ]
-                tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                tags = self.canvas.gettags( item )
 
                 if 'Switch' in tags:
                     opts = self.switchOpts[name]
@@ -2991,9 +2987,9 @@ class MiniEdit( Frame ):
         if len(sflowValues['sflowTarget']) > 0:
             sflowEnabled = False
             sflowSwitches = ''
-            for widget in self.widgetToItem:
+            for widget, item in self.widgetToItem.items():
                 name = widget[ 'text' ]
-                tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                tags = self.canvas.gettags( item )
 
                 if 'Switch' in tags:
                     opts = self.switchOpts[name]
@@ -3036,9 +3032,9 @@ class MiniEdit( Frame ):
             #for switch in self.net.switches:
             #    info( switch.name + ' ')
             #    switch.start( self.net.controllers )
-            for widget in self.widgetToItem:
+            for widget, item in self.widgetToItem.items():
                 name = widget[ 'text' ]
-                tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                tags = self.canvas.gettags( item )
                 if 'Switch' in tags:
                     opts = self.switchOpts[name]
                     switchControllers = []
@@ -3058,9 +3054,9 @@ class MiniEdit( Frame ):
         "Stop network."
         if self.net is not None:
             # Stop host details
-            for widget in self.widgetToItem:
+            for widget, item in self.widgetToItem.items():
                 name = widget[ 'text' ]
-                tags = self.canvas.gettags( self.widgetToItem[ widget ] )
+                tags = self.canvas.gettags( item )
                 if 'Host' in tags:
                     newHost = self.net.get(name)
                     opts = self.hostOpts[name]

examples/multiping.py

@@ -17,9 +17,9 @@ from mininet.topo import SingleSwitchTopo
 from mininet.log import info, setLogLevel
 
 
-def chunks( l, n ):
+def chunks( items, n ):
     "Divide list l into chunks of size n - thanks Stackoverflow"
-    return [ l[ i: i + n ] for i in range( 0, len( l ), n ) ]
+    return [ items[ i: i + n ] for i in range( 0, len( items ), n ) ]
 
 def startpings( host, targetips ):
     "Tell host to repeatedly ping targets"

examples/multipoll.py

@@ -18,10 +18,11 @@ from mininet.util import decode
 
 def monitorFiles( outfiles, seconds, timeoutms ):
     "Monitor set of files and return [(host, line)...]"
-    devnull = open( '/dev/null', 'w' )
+    devnull = open( '/dev/null', 'w' )  # pylint: disable=consider-using-with
     tails, fdToFile, fdToHost = {}, {}, {}
     for h, outfile in outfiles.items():
-        tail = Popen( [ 'tail', '-f', outfile ],
+        tail = Popen(  # pylint: disable=consider-using-with
+            [ 'tail', '-f', outfile ],
             stdout=PIPE, stderr=devnull )
         fd = tail.stdout.fileno()
         tails[ h ] = tail

examples/treeping64.py

@@ -25,9 +25,8 @@ def treePing64():
     switches = { 'reference user': UserSwitch,
                  'Open vSwitch kernel': OVSKernelSwitch }
 
-    for name in switches:
+    for name, switch in switches.items():
         info( "*** Testing", name, "datapath\n" )
-        switch = switches[ name ]
         network = TreeNet( depth=2, fanout=8, switch=switch,
                            waitConnected=True )
         result = network.run( network.pingAll )

mininet/clean.py

@@ -21,7 +21,9 @@ from mininet.util import decode
 def sh( cmd ):
     "Print a command and send it to the shell"
     info( cmd + '\n' )
-    result = Popen( [ '/bin/sh', '-c', cmd ], stdout=PIPE ).communicate()[ 0 ]
+    p = Popen(  # pylint: disable=consider-using-with
+        [ '/bin/sh', '-c', cmd ], stdout=PIPE )
+    result = p.communicate()[ 0 ]
     return decode( result )
 
 def killprocs( pattern ):

mininet/cli.py

@@ -150,7 +150,7 @@ class CLI( Cmd ):
         '  mininet> xterm h2\n\n'
     )
 
-    def do_help( self, line ):  # pylint: disable=arguments-differ
+    def do_help( self, line ):  # pylint: disable=arguments-renamed
         "Describe available CLI commands."
         Cmd.do_help( self, line )
         if line == '':
@@ -352,7 +352,7 @@ class CLI( Cmd ):
             error( 'usage: source <file>\n' )
             return
         try:
-            self.inputFile = open( args[ 0 ] )
+            with open( args[ 0 ] ) as self.inputFile:
                 while True:
                     line = self.inputFile.readline()
                     if len( line ) > 0:
@@ -456,12 +456,14 @@ class CLI( Cmd ):
             try:
                 bothPoller.poll()
                 # XXX BL: this doesn't quite do what we want.
+                # pylint: disable=condition-evals-to-constant
                 if False and self.inputFile:
                     key = self.inputFile.read( 1 )
                     if key != '':
                         node.write( key )
                     else:
                         self.inputFile = None
+                # pylint: enable=condition-evals-to-constant
                 if isReadable( self.inPoller ):
                     key = self.stdin.read( 1 )
                     node.write( key )

mininet/link.py

@@ -316,8 +316,9 @@ class TCIntf( Intf ):
         debug(" *** executing command: %s\n" % c)
         return self.cmd( c )
 
-    # pylint: disable=arguments-differ
+    def config(  # pylint: disable=arguments-renamed,arguments-differ
-    def config( self, bw=None, delay=None, jitter=None, loss=None,
+                self,
+                bw=None, delay=None, jitter=None, loss=None,
                 gro=False, txo=True, rxo=True,
                 speedup=0, use_hfsc=False, use_tbf=False,
                 latency_ms=None, enable_ecn=False, enable_red=False,
@@ -539,9 +540,7 @@ class OVSLink( Link ):
 
     def __init__( self, node1, node2, **kwargs ):
         "See Link.__init__() for options"
-        try:
+        if 'OVSSwitch' not in globals():
-            OVSSwitch
-        except NameError:
             # pylint: disable=import-outside-toplevel,cyclic-import
             from mininet.node import OVSSwitch
         self.isPatchLink = False
@@ -551,7 +550,7 @@ class OVSLink( Link ):
             kwargs.update( cls1=OVSIntf, cls2=OVSIntf )
         Link.__init__( self, node1, node2, **kwargs )
 
-    # pylint: disable=arguments-differ, signature-differs
+    # pylint: disable=arguments-renamed, arguments-differ, signature-differs
     def makeIntfPair( self, *args, **kwargs ):
         "Usually delegated to OVSSwitch"
         if self.isPatchLink:

mininet/net.py

@@ -201,7 +201,7 @@ class Mininet( object ):
             sleep( delay )
             time += delay
         warn( 'Timed out after %d seconds\n' % time )
-        for switch in remaining:
+        for switch in remaining.copy():
             if not switch.connected():
                 warn( 'Warning: %s is not connected to a controller\n'
                       % switch.name )

mininet/node.py

@@ -57,7 +57,6 @@ import pty
 import re
 import signal
 import select
-from distutils.version import StrictVersion
 from re import findall
 from subprocess import Popen, PIPE
 from sys import exit  # pylint: disable=redefined-builtin
@@ -66,7 +65,8 @@ from time import sleep
 from mininet.log import info, error, warn, debug
 from mininet.util import ( quietRun, errRun, errFail, moveIntf, isShellBuiltin,
                            numCores, retry, mountCgroups, BaseString, decode,
-                           encode, getincrementaldecoder, Python3, which )
+                           encode, getincrementaldecoder, Python3, which,
+                           StrictVersion )
 from mininet.moduledeps import moduleDeps, pathCheck, TUN
 from mininet.link import Link, Intf, TCIntf, OVSIntf
 
@@ -219,7 +219,7 @@ class Node( object ):
             params: parameters to Popen()"""
         # Leave this is as an instance method for now
         assert self
-        popen = Popen( cmd, **params )
+        popen = Popen( cmd, **params )  # pylint: disable=consider-using-with
         debug( '_popen', cmd, popen.pid )
         return popen
 

mininet/test/test_walkthrough.py

@@ -10,10 +10,9 @@ import os
 import re
 import unittest
 
-from distutils.version import StrictVersion
 from sys import stdout
 
-from mininet.util import quietRun, pexpect
+from mininet.util import quietRun, pexpect, StrictVersion
 from mininet.clean import cleanup
 
 

mininet/topo.py

@@ -336,9 +336,11 @@ class LinearTopo( Topo ):
         self.n = n
 
         if n == 1:
-            genHostName = lambda i, j: 'h%s' % i
+            def genHostName( i, _j ):
+                return 'h%s' % i
         else:
-            genHostName = lambda i, j: 'h%ss%d' % ( j, i )
+            def genHostName( i, j ):
+                return 'h%ss%d' % ( j, i )
 
         lastSwitch = None
         for i in irange( 1, k ):

mininet/topolib.py

@@ -53,9 +53,11 @@ class TorusTopo( Topo ):
             raise Exception( 'Please use 3x3 or greater for compatibility '
                              'with 2.1' )
         if n == 1:
-            genHostName = lambda loc, k: 'h%s' % ( loc )
+            def genHostName( loc, _k ):
+                return 'h%s' % ( loc )
         else:
-            genHostName = lambda loc, k: 'h%sx%d' % ( loc, k )
+            def genHostName( loc, k ):
+                return 'h%sx%d' % ( loc, k )
 
         hosts, switches, dpid = {}, {}, 0
         # Create and wire interior

mininet/util.py

@@ -46,6 +46,7 @@ if Python3:
         "Encode buffer for Python 3"
         return buf.encode( Encoding )
     getincrementaldecoder = codecs.getincrementaldecoder( Encoding )
+
 else:
     decode, encode = NullCodec.decode, NullCodec.encode
 
@@ -54,11 +55,16 @@ else:
         return NullCodec
 
 try:
-    # pylint: disable=import-error
+    import packaging.version  # replacement for distutils.version
+    StrictVersion = packaging.version.parse
+except ImportError:  # python2.7 lacks ModuleNotFoundError
+    import distutils.version  # pylint: disable=deprecated-module
+    StrictVersion = distutils.version.StrictVersion
+
+try:
     oldpexpect = None
-    import pexpect as oldpexpect
+    import pexpect as oldpexpect  # pylint: disable=import-error
 
-    # pylint: enable=import-error
     class Pexpect( object ):
         "Custom pexpect that is compatible with str"
         @staticmethod
@@ -97,11 +103,12 @@ def oldQuietRun( *cmd ):
         cmd = cmd[ 0 ]
         if isinstance( cmd, BaseString ):
             cmd = cmd.split( ' ' )
-    popen = Popen( cmd, stdout=PIPE, stderr=STDOUT )
+    out = ''
+    popen = Popen(  # pylint: disable=consider-using-with
+        cmd, stdout=PIPE, stderr=STDOUT )
     # We can't use Popen.communicate() because it uses
     # select(), which can't handle
     # high file descriptor numbers! poll() can, however.
-    out = ''
     readable = poll()
     readable.register( popen.stdout )
     while True:
@@ -142,6 +149,7 @@ def errRun( *cmd, **kwargs ):
     elif isinstance( cmd, list ) and shell:
         cmd = " ".join( arg for arg in cmd )
     debug( '*** errRun:', cmd, '\n' )
+    # pylint: disable=consider-using-with
     popen = Popen( cmd, stdout=PIPE, stderr=stderr, shell=shell )
     # We use poll() because select() doesn't work with large fd numbers,
     # and thus communicate() doesn't work either