resolve several pylint issues in cqlsh.py and pylib

patch by Brad Schoening; reviewed by Stefan Miklosovic and Brandon Williams for CASSANDRA-17480

CHANGES.txt

@@ -1,4 +1,5 @@
 4.1
+ * resolve several pylint issues in cqlsh.py and pylib (CASSANDRA-17480)
  * Streaming sessions longer than 3 minutes fail with timeout (CASSANDRA-17510)
  * Add ability to track state in repair (CASSANDRA-15399)
  * Remove unused 'parse' module (CASSANDRA-17484)

bin/cqlsh.py

@@ -18,6 +18,7 @@
 
 import cmd
 import codecs
+import configparser
 import csv
 import errno
 import getpass
@@ -33,6 +34,7 @@ import warnings
 import webbrowser
 from contextlib import contextmanager
 from glob import glob
+from io import StringIO
 from uuid import UUID
 
 if sys.version_info < (3, 6):
@@ -118,9 +120,6 @@ for lib in third_parties:
     if lib_zip:
         sys.path.insert(0, lib_zip)
 
-import configparser
-from io import StringIO
-
 warnings.filterwarnings("ignore", r".*blist.*")
 try:
     import cassandra
@@ -225,8 +224,8 @@ parser.add_option('-v', action="version", help='Print the current version of cql
 parser.add_option("--insecure-password-without-warning", action='store_true', dest='insecure_password_without_warning',
                   help=optparse.SUPPRESS_HELP)
 
-optvalues = optparse.Values()
-(options, arguments) = parser.parse_args(sys.argv[1:], values=optvalues)
+opt_values = optparse.Values()
+(options, arguments) = parser.parse_args(sys.argv[1:], values=opt_values)
 
 # BEGIN history/config definition
 
@@ -878,7 +877,7 @@ class Shell(cmd.Cmd):
                 return
             yield newline
 
-    def cmdloop(self):
+    def cmdloop(self, intro=None):
         """
         Adapted from cmd.Cmd's version, because there is literally no way with
         cmd.Cmd.cmdloop() to tell the difference between "EOF" showing up in
@@ -1115,11 +1114,11 @@ class Shell(cmd.Cmd):
         def print_all(result, table_meta, tty):
             # Return the number of rows in total
             num_rows = 0
-            isFirst = True
+            is_first = True
             while True:
                 # Always print for the first page even it is empty
-                if result.current_rows or isFirst:
-                    with_header = isFirst or tty
+                if result.current_rows or is_first:
+                    with_header = is_first or tty
                     self.print_static_result(result, table_meta, with_header, tty, num_rows)
                     num_rows += len(result.current_rows)
                 if result.has_more_pages:
@@ -1131,7 +1130,7 @@ class Shell(cmd.Cmd):
                     if not tty:
                         self.writeresult("")
                     break
-                isFirst = False
+                is_first = False
             return num_rows
 
         num_rows = print_all(result, table_meta, self.tty)
@@ -2067,7 +2066,7 @@ class SwitchCommandWithValue(SwitchCommand):
             binary_switch_value = True
         except (ValueError, TypeError):
             value = None
-        return (binary_switch_value, value)
+        return binary_switch_value, value
 
 
 def option_with_default(cparser_getter, section, option, default=None):

pylib/cqlshlib/copyutil.py

@@ -88,7 +88,7 @@ def printmsg(msg, eol='\n', encoding='utf8'):
 
 # Keep arguments in sync with printmsg
 def swallowmsg(msg, eol='', encoding=''):
-    None
+    pass
 
 
 class OneWayPipe(object):
@@ -288,7 +288,7 @@ class CopyTask(object):
             return opts
 
         configs = configparser.RawConfigParser()
-        configs.readfp(open(config_file))
+        configs.read_file(open(config_file))
 
         ret = dict()
         config_sections = list(['copy', 'copy-%s' % (direction,),

pylib/cqlshlib/cql3handling.py

@@ -18,8 +18,9 @@ from cassandra.metadata import maybe_escape_name
 from cqlshlib import helptopics
 from cqlshlib.cqlhandling import CqlParsingRuleSet, Hint
 
-simple_cql_types = set(('ascii', 'bigint', 'blob', 'boolean', 'counter', 'date', 'decimal', 'double', 'duration', 'float',
-                        'inet', 'int', 'smallint', 'text', 'time', 'timestamp', 'timeuuid', 'tinyint', 'uuid', 'varchar', 'varint'))
+simple_cql_types = {'ascii', 'bigint', 'blob', 'boolean', 'counter', 'date', 'decimal', 'double', 'duration', 'float',
+                    'inet', 'int', 'smallint', 'text', 'time', 'timestamp', 'timeuuid', 'tinyint', 'uuid', 'varchar',
+                    'varint'}
 simple_cql_types.difference_update(('set', 'map', 'list'))
 
 cqldocs = helptopics.CQL3HelpTopics()
@@ -450,7 +451,7 @@ def ks_prop_val_mapkey_completer(ctxt, cass):
     else:
         return ["'class'"]
     if repclass == 'SimpleStrategy':
-        opts = set(('replication_factor',))
+        opts = {'replication_factor'}
     elif repclass == 'NetworkTopologyStrategy':
         return [Hint('<dc_name>')]
     return list(map(escape_value, opts.difference(keysseen)))

pylib/cqlshlib/cqlhandling.py

@@ -24,13 +24,12 @@ from cqlshlib import pylexotron, util
 
 Hint = pylexotron.Hint
 
-cql_keywords_reserved = set((
-    'add', 'allow', 'alter', 'and', 'apply', 'asc', 'authorize', 'batch', 'begin', 'by', 'columnfamily', 'create',
-    'delete', 'desc', 'describe', 'drop', 'entries', 'execute', 'from', 'full', 'grant', 'if', 'in', 'index',
-    'infinity', 'insert', 'into', 'is', 'keyspace', 'limit', 'materialized', 'modify', 'nan', 'norecursive', 'not',
-    'null', 'of', 'on', 'or', 'order', 'primary', 'rename', 'revoke', 'schema', 'select', 'set', 'table', 'to', 'token',
-    'truncate', 'unlogged', 'update', 'use', 'using', 'view', 'where', 'with'
-))
+cql_keywords_reserved = {'add', 'allow', 'alter', 'and', 'apply', 'asc', 'authorize', 'batch', 'begin', 'by',
+                         'columnfamily', 'create', 'delete', 'desc', 'describe', 'drop', 'entries', 'execute', 'from',
+                         'full', 'grant', 'if', 'in', 'index', 'infinity', 'insert', 'into', 'is', 'keyspace', 'limit',
+                         'materialized', 'modify', 'nan', 'norecursive', 'not', 'null', 'of', 'on', 'or', 'order',
+                         'primary', 'rename', 'revoke', 'schema', 'select', 'set', 'table', 'to', 'token', 'truncate',
+                         'unlogged', 'update', 'use', 'using', 'view', 'where', 'with'}
 """
 Set of reserved keywords in CQL.
 
@@ -60,7 +59,7 @@ class CqlParsingRuleSet(pylexotron.ParsingRuleSet):
     )
 
     def __init__(self, *args, **kwargs):
-        pylexotron.ParsingRuleSet.__init__(self, *args, **kwargs)
+        pylexotron.ParsingRuleSet.__init__(self)
 
         # note: commands_end_with_newline may be extended by callers.
         self.commands_end_with_newline = set()
@@ -152,10 +151,10 @@ class CqlParsingRuleSet(pylexotron.ParsingRuleSet):
                     in_batch = True
         return output, in_batch or in_pg_string
 
-    def cql_complete_single(self, text, partial, init_bindings={}, ignore_case=True,
+    def cql_complete_single(self, text, partial, init_bindings=None, ignore_case=True,
                             startsymbol='Start'):
         tokens = (self.cql_split_statements(text)[0] or [[]])[-1]
-        bindings = init_bindings.copy()
+        bindings = {} if init_bindings is None else init_bindings.copy()
 
         # handle some different completion scenarios- in particular, completing
         # inside a string literal