Revert "Revert "pylint: upgrade to 1.3.1""

third_party/pylint/checkers/base.py

-# Copyright (c) 2003-2010 LOGILAB S.A. (Paris, FRANCE).
+# Copyright (c) 2003-2013 LOGILAB S.A. (Paris, FRANCE).
+# http://www.logilab.fr/ -- mailto:contact@logilab.fr
 # Copyright (c) 2009-2010 Arista Networks, Inc.
-# http://www.logilab.fr/ -- mailto:contact@logilab.fr
+#
 # This program is free software; you can redistribute it and/or modify it under
 # the terms of the GNU General Public License as published by the Free Software
 # Foundation; either version 2 of the License, or (at your option) any later
 # version.
 #
 # This program is distributed in the hope that it will be useful, but WITHOUT
 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 # FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License along with
 # this program; if not, write to the Free Software Foundation, Inc.,
-# 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 """basic checker for Python code"""
 
+import sys
+import astroid
+from logilab.common.ureports import Table
+from astroid import are_exclusive, InferenceError
+import astroid.bases
 
-from logilab import astng
-from logilab.common.ureports import Table
-from logilab.astng import are_exclusive
-
-from pylint.interfaces import IASTNGChecker
+from pylint.interfaces import IAstroidChecker
+from pylint.utils import EmptyReport
 from pylint.reporters import diff_string
-from pylint.checkers import BaseChecker, EmptyReport
-from pylint.checkers.utils import check_messages, clobber_in_except, is_inside_except
+from pylint.checkers import BaseChecker
+from pylint.checkers.utils import (
+    check_messages,
+    clobber_in_except,
+    is_builtin_object,
+    is_inside_except,
+    overrides_a_method,
+    safe_infer,
+    get_argument_from_call,
+    NoSuchArgumentError,
+    )
 
 
 import re
 
 # regex for class/function/variable/constant name
 CLASS_NAME_RGX = re.compile('[A-Z_][a-zA-Z0-9]+$')
 MOD_NAME_RGX = re.compile('(([a-z_][a-z0-9_]*)|([A-Z][a-zA-Z0-9]+))$')
 CONST_NAME_RGX = re.compile('(([A-Z_][A-Z0-9_]*)|(__.*__))$')
 COMP_VAR_RGX = re.compile('[A-Za-z_][A-Za-z0-9_]*$')
 DEFAULT_NAME_RGX = re.compile('[a-z_][a-z0-9_]{2,30}$')
+CLASS_ATTRIBUTE_RGX = re.compile(r'([A-Za-z_][A-Za-z0-9_]{2,30}|(__.*__))$')
 # do not require a doc string on system methods
 NO_REQUIRED_DOC_RGX = re.compile('__.*__')
+REVERSED_METHODS = (('__getitem__', '__len__'),
+                    ('__reversed__', ))
+
+PY33 = sys.version_info >= (3, 3)
+PY3K = sys.version_info >= (3, 0)
+BAD_FUNCTIONS = ['map', 'filter', 'apply']
+if sys.version_info < (3, 0):
+    BAD_FUNCTIONS.append('input')
+    BAD_FUNCTIONS.append('file')
+
+# Name categories that are always consistent with all naming conventions.
+EXEMPT_NAME_CATEGORIES = set(('exempt', 'ignore'))
 
 del re
 
 def in_loop(node):
     """return True if the node is inside a kind of for loop"""
     parent = node.parent
     while parent is not None:
-        if isinstance(parent, (astng.For, astng.ListComp, astng.SetComp,
-                               astng.DictComp, astng.GenExpr)):
+        if isinstance(parent, (astroid.For, astroid.ListComp, astroid.SetComp,
+                               astroid.DictComp, astroid.GenExpr)):
             return True
         parent = parent.parent
     return False
 
 def in_nested_list(nested_list, obj):
     """return true if the object is an element of <nested_list> or of a nested
     list
     """
     for elmt in nested_list:
         if isinstance(elmt, (list, tuple)):
             if in_nested_list(elmt, obj):
                 return True
         elif elmt == obj:
             return True
     return False
 
+def _loop_exits_early(loop):
+    """Returns true if a loop has a break statement in its body."""
+    loop_nodes = (astroid.For, astroid.While)
+    # Loop over body explicitly to avoid matching break statements
+    # in orelse.
+    for child in loop.body:
+        if isinstance(child, loop_nodes):
+            # break statement may be in orelse of child loop.
+            for orelse in (child.orelse or ()):
+                for _ in orelse.nodes_of_class(astroid.Break, skip_klass=loop_nodes):
+                    return True
+            continue
+        for _ in child.nodes_of_class(astroid.Break, skip_klass=loop_nodes):
+            return True
+    return False
+
+if sys.version_info < (3, 0):
+    PROPERTY_CLASSES = set(('__builtin__.property', 'abc.abstractproperty'))
+else:
+    PROPERTY_CLASSES = set(('builtins.property', 'abc.abstractproperty'))
+ABC_METHODS = set(('abc.abstractproperty', 'abc.abstractmethod',
+                   'abc.abstractclassmethod', 'abc.abstractstaticmethod'))
+
+def _determine_function_name_type(node):
+    """Determine the name type whose regex the a function's name should match.
+
+    :param node: A function node.
+    :returns: One of ('function', 'method', 'attr')
+    """
+    if not node.is_method():
+        return 'function'
+    if node.decorators:
+        decorators = node.decorators.nodes
+    else:
+        decorators = []
+    for decorator in decorators:
+        # If the function is a property (decorated with @property
+        # or @abc.abstractproperty), the name type is 'attr'.
+        if (isinstance(decorator, astroid.Name) or
+                (isinstance(decorator, astroid.Getattr) and
+                 decorator.attrname == 'abstractproperty')):
+            infered = safe_infer(decorator)
+            if infered and infered.qname() in PROPERTY_CLASSES:
+                return 'attr'
+        # If the function is decorated using the prop_method.{setter,getter}
+        # form, treat it like an attribute as well.
+        elif (isinstance(decorator, astroid.Getattr) and
+              decorator.attrname in ('setter', 'deleter')):
+            return 'attr'
+    return 'method'
+
+def decorated_with_abc(func):
+    """ Determine if the `func` node is decorated
+    with `abc` decorators (abstractmethod et co.)
+    """
+    if func.decorators:
+        for node in func.decorators.nodes:
+            try:
+                infered = node.infer().next()
+            except InferenceError:
+                continue
+            if infered and infered.qname() in ABC_METHODS:
+                return True
+
+def has_abstract_methods(node):
+    """ Determine if the given `node` has
+    abstract methods, defined with `abc` module.
+    """
+    return any(decorated_with_abc(meth)
+               for meth in node.mymethods())
+
 def report_by_type_stats(sect, stats, old_stats):
     """make a report of
 
     * percentage of different types documented
     * percentage of different types with a bad name
     """
     # percentage of different types documented and/or with a bad name
     nice_stats = {}
     for node_type in ('module', 'class', 'method', 'function'):
         try:
@@ skipping 31 matching lines @@
     """return True if the object is a method redefined via decorator.
 
     For example:
         @property
         def x(self): return self._x
         @x.setter
         def x(self, value): self._x = value
     """
     if node.decorators:
         for decorator in node.decorators.nodes:
-            if (isinstance(decorator, astng.Getattr) and
-                decorator.expr.name == node.name):
+            if (isinstance(decorator, astroid.Getattr) and
+                    getattr(decorator.expr, 'name', None) == node.name):
                 return True
     return False
 
 class _BasicChecker(BaseChecker):
-    __implements__ = IASTNGChecker
+    __implements__ = IAstroidChecker
     name = 'basic'
 
 class BasicErrorChecker(_BasicChecker):
     msgs = {
-    'E0100': ('__init__ method is a generator',
-              'Used when the special class method __init__ is turned into a '
-              'generator by a yield in its body.'),
-    'E0101': ('Explicit return in __init__',
-              'Used when the special class method __init__ has an explicit \
-              return value.'),
-    'E0102': ('%s already defined line %s',
-              'Used when a function / class / method is redefined.'),
-    'E0103': ('%r not properly in loop',
-              'Used when break or continue keywords are used outside a loop.'),
+        'E0100': ('__init__ method is a generator',
+                  'init-is-generator',
+                  'Used when the special class method __init__ is turned into a '
+                  'generator by a yield in its body.'),
+        'E0101': ('Explicit return in __init__',
+                  'return-in-init',
+                  'Used when the special class method __init__ has an explicit '
+                  'return value.'),
+        'E0102': ('%s already defined line %s',
+                  'function-redefined',
+                  'Used when a function / class / method is redefined.'),
+        'E0103': ('%r not properly in loop',
+                  'not-in-loop',
+                  'Used when break or continue keywords are used outside a loop.'),
+        'E0104': ('Return outside function',
+                  'return-outside-function',
+                  'Used when a "return" statement is found outside a function or '
+                  'method.'),
+        'E0105': ('Yield outside function',
+                  'yield-outside-function',
+                  'Used when a "yield" statement is found outside a function or '
+                  'method.'),
+        'E0106': ('Return with argument inside generator',
+                  'return-arg-in-generator',
+                  'Used when a "return" statement with an argument is found '
+                  'outside in a generator function or method (e.g. with some '
+                  '"yield" statements).',
+                  {'maxversion': (3, 3)}),
+        'E0107': ("Use of the non-existent %s operator",
+                  'nonexistent-operator',
+                  "Used when you attempt to use the C-style pre-increment or"
+                  "pre-decrement operator -- and ++, which doesn't exist in Python."),
+        'E0108': ('Duplicate argument name %s in function definition',
+                  'duplicate-argument-name',
+                  'Duplicate argument names in function definitions are syntax'
+                  ' errors.'),
+        'E0110': ('Abstract class with abstract methods instantiated',
+                  'abstract-class-instantiated',
+                  'Used when an abstract class with `abc.ABCMeta` as metaclass '
+                  'has abstract methods and is instantiated.',
+                  {'minversion': (3, 0)}),
+        'W0120': ('Else clause on loop without a break statement',
+                  'useless-else-on-loop',
+                  'Loops should only have an else clause if they can exit early '
+                  'with a break statement, otherwise the statements under else '
+                  'should be on the same scope as the loop itself.'),
+        }
 
-    'E0104': ('Return outside function',
-              'Used when a "return" statement is found outside a function or '
-              'method.'),
-    'E0105': ('Yield outside function',
-              'Used when a "yield" statement is found outside a function or '
-              'method.'),
-    'E0106': ('Return with argument inside generator',
-              'Used when a "return" statement with an argument is found '
-              'outside in a generator function or method (e.g. with some '
-              '"yield" statements).'),
-    'E0107': ("Use of the non-existent %s operator",
-              "Used when you attempt to use the C-style pre-increment or"
-              "pre-decrement operator -- and ++, which doesn't exist in Python."),
-    }
-
-    def __init__(self, linter):
-        _BasicChecker.__init__(self, linter)
-
-    @check_messages('E0102')
+    @check_messages('function-redefined')
     def visit_class(self, node):
         self._check_redefinition('class', node)
 
-    @check_messages('E0100', 'E0101', 'E0102', 'E0106')
+    @check_messages('init-is-generator', 'return-in-init',
+                    'function-redefined', 'return-arg-in-generator',
+                    'duplicate-argument-name')
     def visit_function(self, node):
         if not redefined_by_decorator(node):
             self._check_redefinition(node.is_method() and 'method' or 'function', node)
         # checks for max returns, branch, return in __init__
-        returns = node.nodes_of_class(astng.Return,
-                                      skip_klass=(astng.Function, astng.Class))
+        returns = node.nodes_of_class(astroid.Return,
+                                      skip_klass=(astroid.Function, astroid.Class))
         if node.is_method() and node.name == '__init__':
             if node.is_generator():
-                self.add_message('E0100', node=node)
+                self.add_message('init-is-generator', node=node)
             else:
                 values = [r.value for r in returns]
-                if  [v for v in values if not (v is None or
-                    (isinstance(v, astng.Const) and v.value is None)
-                    or  (isinstance(v, astng.Name) and v.name == 'None'))]:
-                    self.add_message('E0101', node=node)
+                # Are we returning anything but None from constructors
+                if [v for v in values
+                        if not (v is None or
+                                (isinstance(v, astroid.Const) and v.value is None) or
+                                (isinstance(v, astroid.Name)  and v.name == 'None')
+                               )]:
+                    self.add_message('return-in-init', node=node)
         elif node.is_generator():
             # make sure we don't mix non-None returns and yields
-            for retnode in returns:
-                if isinstance(retnode.value, astng.Const) and \
-                       retnode.value.value is not None:
-                    self.add_message('E0106', node=node,
-                                     line=retnode.fromlineno)
+            if not PY33:
+                for retnode in returns:
+                    if isinstance(retnode.value, astroid.Const) and \
+                           retnode.value.value is not None:
+                        self.add_message('return-arg-in-generator', node=node,
+                                         line=retnode.fromlineno)
+        # Check for duplicate names
+        args = set()
+        for name in node.argnames():
+            if name in args:
+                self.add_message('duplicate-argument-name', node=node, args=(name,))
+            else:
+                args.add(name)
 
-    @check_messages('E0104')
+
+    @check_messages('return-outside-function')
     def visit_return(self, node):
-        if not isinstance(node.frame(), astng.Function):
-            self.add_message('E0104', node=node)
+        if not isinstance(node.frame(), astroid.Function):
+            self.add_message('return-outside-function', node=node)
 
-    @check_messages('E0105')
+    @check_messages('yield-outside-function')
     def visit_yield(self, node):
-        if not isinstance(node.frame(), astng.Function):
-            self.add_message('E0105', node=node)
+        if not isinstance(node.frame(), (astroid.Function, astroid.Lambda)):
+            self.add_message('yield-outside-function', node=node)
 
-    @check_messages('E0103')
+    @check_messages('not-in-loop')
     def visit_continue(self, node):
         self._check_in_loop(node, 'continue')
 
-    @check_messages('E0103')
+    @check_messages('not-in-loop')
     def visit_break(self, node):
         self._check_in_loop(node, 'break')
 
-    @check_messages('E0107')
+    @check_messages('useless-else-on-loop')
+    def visit_for(self, node):
+        self._check_else_on_loop(node)
+
+    @check_messages('useless-else-on-loop')
+    def visit_while(self, node):
+        self._check_else_on_loop(node)
+
+    @check_messages('nonexistent-operator')
     def visit_unaryop(self, node):
-        """check use of the non-existent ++ adn -- operator operator"""
+        """check use of the non-existent ++ and -- operator operator"""
         if ((node.op in '+-') and
-            isinstance(node.operand, astng.UnaryOp) and
-            (node.operand.op == node.op)):
-            self.add_message('E0107', node=node, args=node.op*2)
+                isinstance(node.operand, astroid.UnaryOp) and
+                (node.operand.op == node.op)):
+            self.add_message('nonexistent-operator', node=node, args=node.op*2)
+
+    @check_messages('abstract-class-instantiated')
+    def visit_callfunc(self, node):
+        """ Check instantiating abstract class with
+        abc.ABCMeta as metaclass.
+        """
+        try:
+            infered = node.func.infer().next()
+        except astroid.InferenceError:
+            return
+        if not isinstance(infered, astroid.Class):
+            return
+        # __init__ was called
+        metaclass = infered.metaclass()
+        if metaclass is None:
+            # Python 3.4 has `abc.ABC`, which won't be detected
+            # by ClassNode.metaclass()
+            for ancestor in infered.ancestors():
+                if (ancestor.qname() == 'abc.ABC' and
+                        has_abstract_methods(infered)):
+                    self.add_message('abstract-class-instantiated', node=node)
+                    break
+            return
+        if (metaclass.qname() == 'abc.ABCMeta' and
+                has_abstract_methods(infered)):
+            self.add_message('abstract-class-instantiated', node=node)
+
+    def _check_else_on_loop(self, node):
+        """Check that any loop with an else clause has a break statement."""
+        if node.orelse and not _loop_exits_early(node):
+            self.add_message('useless-else-on-loop', node=node,
+                             # This is not optimal, but the line previous
+                             # to the first statement in the else clause
+                             # will usually be the one that contains the else:.
+                             line=node.orelse[0].lineno - 1)
 
     def _check_in_loop(self, node, node_name):
         """check that a node is inside a for or while loop"""
         _node = node.parent
         while _node:
-            if isinstance(_node, (astng.For, astng.While)):
+            if isinstance(_node, (astroid.For, astroid.While)):
                 break
             _node = _node.parent
         else:
-            self.add_message('E0103', node=node, args=node_name)
+            self.add_message('not-in-loop', node=node, args=node_name)
 
     def _check_redefinition(self, redeftype, node):
         """check for redefinition of a function / method / class name"""
         defined_self = node.parent.frame()[node.name]
         if defined_self is not node and not are_exclusive(node, defined_self):
-            self.add_message('E0102', node=node,
+            self.add_message('function-redefined', node=node,
                              args=(redeftype, defined_self.fromlineno))
 
 
 
 class BasicChecker(_BasicChecker):
     """checks for :
     * doc strings
-    * modules / classes / functions / methods / arguments / variables name
     * number of arguments, local variables, branches, returns and statements in
 functions, methods
     * required module attributes
     * dangerous default values as arguments
     * redefinition of function / method / class
     * uses of the global statement
     """
 
-    __implements__ = IASTNGChecker
+    __implements__ = IAstroidChecker
 
     name = 'basic'
     msgs = {
-    'W0101': ('Unreachable code',
-              'Used when there is some code behind a "return" or "raise" \
-              statement, which will never be accessed.'),
-    'W0102': ('Dangerous default value %s as argument',
-              'Used when a mutable value as list or dictionary is detected in \
-              a default value for an argument.'),
-    'W0104': ('Statement seems to have no effect',
-              'Used when a statement doesn\'t have (or at least seems to) \
-              any effect.'),
-    'W0105': ('String statement has no effect',
-              'Used when a string is used as a statement (which of course \
-              has no effect). This is a particular case of W0104 with its \
-              own message so you can easily disable it if you\'re using \
-              those strings as documentation, instead of comments.'),
-    'W0106': ('Expression "%s" is assigned to nothing',
-              'Used when an expression that is not a function call is assigned\
-              to nothing. Probably something else was intended.'),
-    'W0108': ('Lambda may not be necessary',
-              'Used when the body of a lambda expression is a function call \
-              on the same argument list as the lambda itself; such lambda \
-              expressions are in all but a few cases replaceable with the \
-              function being called in the body of the lambda.'),
-    'W0109': ("Duplicate key %r in dictionary",
-              "Used when a dictionary expression binds the same key multiple \
-              times."),
-    'W0122': ('Use of the exec statement',
-              'Used when you use the "exec" statement, to discourage its \
-              usage. That doesn\'t mean you can not use it !'),
+        'W0101': ('Unreachable code',
+                  'unreachable',
+                  'Used when there is some code behind a "return" or "raise" '
+                  'statement, which will never be accessed.'),
+        'W0102': ('Dangerous default value %s as argument',
+                  'dangerous-default-value',
+                  'Used when a mutable value as list or dictionary is detected in '
+                  'a default value for an argument.'),
+        'W0104': ('Statement seems to have no effect',
+                  'pointless-statement',
+                  'Used when a statement doesn\'t have (or at least seems to) '
+                  'any effect.'),
+        'W0105': ('String statement has no effect',
+                  'pointless-string-statement',
+                  'Used when a string is used as a statement (which of course '
+                  'has no effect). This is a particular case of W0104 with its '
+                  'own message so you can easily disable it if you\'re using '
+                  'those strings as documentation, instead of comments.'),
+        'W0106': ('Expression "%s" is assigned to nothing',
+                  'expression-not-assigned',
+                  'Used when an expression that is not a function call is assigned '
+                  'to nothing. Probably something else was intended.'),
+        'W0108': ('Lambda may not be necessary',
+                  'unnecessary-lambda',
+                  'Used when the body of a lambda expression is a function call '
+                  'on the same argument list as the lambda itself; such lambda '
+                  'expressions are in all but a few cases replaceable with the '
+                  'function being called in the body of the lambda.'),
+        'W0109': ("Duplicate key %r in dictionary",
+                  'duplicate-key',
+                  'Used when a dictionary expression binds the same key multiple '
+                  'times.'),
+        'W0122': ('Use of exec',
+                  'exec-used',
+                  'Used when you use the "exec" statement (function for Python 3), to discourage its '
+                  'usage. That doesn\'t mean you can not use it !'),
+        'W0123': ('Use of eval',
+                  'eval-used',
+                  'Used when you use the "eval" function, to discourage its '
+                  'usage. Consider using `ast.literal_eval` for safely evaluating '
+                  'strings containing Python expressions '
+                  'from untrusted sources. '),
+        'W0141': ('Used builtin function %r',
+                  'bad-builtin',
+                  'Used when a black listed builtin function is used (see the '
+                  'bad-function option). Usual black listed functions are the ones '
+                  'like map, or filter , where Python offers now some cleaner '
+                  'alternative like list comprehension.'),
+        'W0142': ('Used * or ** magic',
+                  'star-args',
+                  'Used when a function or method is called using `*args` or '
+                  '`**kwargs` to dispatch arguments. This doesn\'t improve '
+                  'readability and should be used with care.'),
+        'W0150': ("%s statement in finally block may swallow exception",
+                  'lost-exception',
+                  'Used when a break or a return statement is found inside the '
+                  'finally clause of a try...finally block: the exceptions raised '
+                  'in the try clause will be silently swallowed instead of being '
+                  're-raised.'),
+        'W0199': ('Assert called on a 2-uple. Did you mean \'assert x,y\'?',
+                  'assert-on-tuple',
+                  'A call of assert on a tuple will always evaluate to true if '
+                  'the tuple is not empty, and will always evaluate to false if '
+                  'it is.'),
+        'W0121': ('Use raise ErrorClass(args) instead of raise ErrorClass, args.',
+                  'old-raise-syntax',
+                  "Used when the alternate raise syntax 'raise foo, bar' is used "
+                  "instead of 'raise foo(bar)'.",
+                  {'maxversion': (3, 0)}),
 
-    'W0141': ('Used builtin function %r',
-              'Used when a black listed builtin function is used (see the '
-              'bad-function option). Usual black listed functions are the ones '
-              'like map, or filter , where Python offers now some cleaner '
-              'alternative like list comprehension.'),
-    'W0142': ('Used * or ** magic',
-              'Used when a function or method is called using `*args` or '
-              '`**kwargs` to dispatch arguments. This doesn\'t improve '
-              'readability and should be used with care.'),
-    'W0150': ("%s statement in finally block may swallow exception",
-              "Used when a break or a return statement is found inside the \
-              finally clause of a try...finally block: the exceptions raised \
-              in the try clause will be silently swallowed instead of being \
-              re-raised."),
-    'W0199': ('Assert called on a 2-uple. Did you mean \'assert x,y\'?',
-              'A call of assert on a tuple will always evaluate to true if '
-              'the tuple is not empty, and will always evaluate to false if '
-              'it is.'),
+        'C0121': ('Missing required attribute "%s"', # W0103
+                  'missing-module-attribute',
+                  'Used when an attribute required for modules is missing.'),
 
-    'C0121': ('Missing required attribute "%s"', # W0103
-              'Used when an attribute required for modules is missing.'),
+        'E0109': ('Missing argument to reversed()',
+                  'missing-reversed-argument',
+                  'Used when reversed() builtin didn\'t receive an argument.'),
+        'E0111': ('The first reversed() argument is not a sequence',
+                  'bad-reversed-sequence',
+                  'Used when the first argument to reversed() builtin '
+                  'isn\'t a sequence (does not implement __reversed__, '
+                  'nor __getitem__ and __len__'),
 
     }
 
     options = (('required-attributes',
                 {'default' : (), 'type' : 'csv',
                  'metavar' : '<attributes>',
                  'help' : 'Required attributes for module, separated by a '
                           'comma'}
-                ),
+               ),
                ('bad-functions',
-                {'default' : ('map', 'filter', 'apply', 'input'),
+                {'default' : BAD_FUNCTIONS,
                  'type' :'csv', 'metavar' : '<builtin function names>',
                  'help' : 'List of builtins function names that should not be '
                           'used, separated by a comma'}
-                ),
-               )
-    reports = ( ('RP0101', 'Statistics by type', report_by_type_stats), )
+               ),
+              )
+    reports = (('RP0101', 'Statistics by type', report_by_type_stats),)
 
     def __init__(self, linter):
         _BasicChecker.__init__(self, linter)
         self.stats = None
         self._tryfinallys = None
 
     def open(self):
         """initialize visit variables and statistics
         """
         self._tryfinallys = []
         self.stats = self.linter.add_stats(module=0, function=0,
                                            method=0, class_=0)
-
+    @check_messages('missing-module-attribute')
     def visit_module(self, node):
         """check module name, docstring and required arguments
         """
         self.stats['module'] += 1
         for attr in self.config.required_attributes:
             if attr not in node:
-                self.add_message('C0121', node=node, args=attr)
+                self.add_message('missing-module-attribute', node=node, args=attr)
 
     def visit_class(self, node):
         """check module name, docstring and redefinition
         increment branch counter
         """
         self.stats['class'] += 1
 
-    @check_messages('W0104', 'W0105')
+    @check_messages('pointless-statement', 'pointless-string-statement',
+                    'expression-not-assigned')
     def visit_discard(self, node):
         """check for various kind of statements without effect"""
         expr = node.value
-        if isinstance(expr, astng.Const) and isinstance(expr.value,
-                                                        basestring):
+        if isinstance(expr, astroid.Const) and isinstance(expr.value,
+                                                          basestring):
             # treat string statement in a separated message
-            self.add_message('W0105', node=node)
+            # Handle PEP-257 attribute docstrings.
+            # An attribute docstring is defined as being a string right after
+            # an assignment at the module level, class level or __init__ level.
+            scope = expr.scope()
+            if isinstance(scope, (astroid.Class, astroid.Module, astroid.Function)):
+                if isinstance(scope, astroid.Function) and scope.name != '__init__':
+                    pass
+                else:
+                    sibling = expr.previous_sibling()
+                    if (sibling is not None and sibling.scope() is scope and
+                            isinstance(sibling, astroid.Assign)):
+                        return
+            self.add_message('pointless-string-statement', node=node)
             return
         # ignore if this is :
         # * a direct function call
         # * the unique child of a try/except body
         # * a yield (which are wrapped by a discard node in _ast XXX)
         # warn W0106 if we have any underlying function call (we can't predict
-        # side effects), else W0104
-        if (isinstance(expr, (astng.Yield, astng.CallFunc)) or
-            (isinstance(node.parent, astng.TryExcept) and
-             node.parent.body == [node])):
+        # side effects), else pointless-statement
+        if (isinstance(expr, (astroid.Yield, astroid.CallFunc)) or
+                (isinstance(node.parent, astroid.TryExcept) and
+                 node.parent.body == [node])):
             return
-        if any(expr.nodes_of_class(astng.CallFunc)):
-            self.add_message('W0106', node=node, args=expr.as_string())
+        if any(expr.nodes_of_class(astroid.CallFunc)):
+            self.add_message('expression-not-assigned', node=node,
+                             args=expr.as_string())
         else:
-            self.add_message('W0104', node=node)
+            self.add_message('pointless-statement', node=node)
 
-    @check_messages('W0108')
+    @check_messages('unnecessary-lambda')
     def visit_lambda(self, node):
         """check whether or not the lambda is suspicious
         """
         # if the body of the lambda is a call expression with the same
         # argument list as the lambda itself, then the lambda is
         # possibly unnecessary and at least suspicious.
         if node.args.defaults:
             # If the arguments of the lambda include defaults, then a
             # judgment cannot be made because there is no way to check
             # that the defaults defined by the lambda are the same as
             # the defaults defined by the function called in the body
             # of the lambda.
             return
         call = node.body
-        if not isinstance(call, astng.CallFunc):
+        if not isinstance(call, astroid.CallFunc):
             # The body of the lambda must be a function call expression
             # for the lambda to be unnecessary.
             return
-        # XXX are lambda still different with astng >= 0.18 ?
+        # XXX are lambda still different with astroid >= 0.18 ?
         # *args and **kwargs need to be treated specially, since they
         # are structured differently between the lambda and the function
         # call (in the lambda they appear in the args.args list and are
         # indicated as * and ** by two bits in the lambda's flags, but
         # in the function call they are omitted from the args list and
         # are indicated by separate attributes on the function call node).
         ordinary_args = list(node.args.args)
         if node.args.kwarg:
             if (not call.kwargs
-                or not isinstance(call.kwargs, astng.Name)
-                or node.args.kwarg != call.kwargs.name):
+                    or not isinstance(call.kwargs, astroid.Name)
+                    or node.args.kwarg != call.kwargs.name):
                 return
         elif call.kwargs:
             return
         if node.args.vararg:
             if (not call.starargs
-                or not isinstance(call.starargs, astng.Name)
-                or node.args.vararg != call.starargs.name):
+                    or not isinstance(call.starargs, astroid.Name)
+                    or node.args.vararg != call.starargs.name):
                 return
         elif call.starargs:
             return
         # The "ordinary" arguments must be in a correspondence such that:
         # ordinary_args[i].name == call.args[i].name.
         if len(ordinary_args) != len(call.args):
             return
         for i in xrange(len(ordinary_args)):
-            if not isinstance(call.args[i], astng.Name):
+            if not isinstance(call.args[i], astroid.Name):
                 return
             if node.args.args[i].name != call.args[i].name:
                 return
-        self.add_message('W0108', line=node.fromlineno, node=node)
+        if (isinstance(node.body.func, astroid.Getattr) and
+            isinstance(node.body.func.expr, astroid.CallFunc)):
+            # Chained call, the intermediate call might
+            # return something else (but we don't check that, yet).
+            return
+        self.add_message('unnecessary-lambda', line=node.fromlineno, node=node)
 
+    @check_messages('dangerous-default-value')
     def visit_function(self, node):
         """check function name, docstring, arguments, redefinition,
         variable names, max locals
         """
         self.stats[node.is_method() and 'method' or 'function'] += 1
         # check for dangerous default values as arguments
         for default in node.args.defaults:
             try:
                 value = default.infer().next()
-            except astng.InferenceError:
+            except astroid.InferenceError:
                 continue
-            if isinstance(value, (astng.Dict, astng.List)):
+            builtins = astroid.bases.BUILTINS
+            if (isinstance(value, astroid.Instance) and
+                    value.qname() in ['.'.join([builtins, x]) for x in ('set', 'dict', 'list')]):
                 if value is default:
                     msg = default.as_string()
+                elif type(value) is astroid.Instance:
+                    msg = '%s (%s)' % (default.as_string(), value.qname())
                 else:
                     msg = '%s (%s)' % (default.as_string(), value.as_string())
-                self.add_message('W0102', node=node, args=(msg,))
+                self.add_message('dangerous-default-value', node=node, args=(msg,))
 
-    @check_messages('W0101', 'W0150')
+    @check_messages('unreachable', 'lost-exception')
     def visit_return(self, node):
         """1 - check is the node has a right sibling (if so, that's some
         unreachable code)
         2 - check is the node is inside the finally clause of a try...finally
         block
         """
         self._check_unreachable(node)
         # Is it inside final body of a try...finally bloc ?
-        self._check_not_in_finally(node, 'return', (astng.Function,))
+        self._check_not_in_finally(node, 'return', (astroid.Function,))
 
-    @check_messages('W0101')
+    @check_messages('unreachable')
     def visit_continue(self, node):
         """check is the node has a right sibling (if so, that's some unreachable
         code)
         """
         self._check_unreachable(node)
 
-    @check_messages('W0101', 'W0150')
+    @check_messages('unreachable', 'lost-exception')
     def visit_break(self, node):
         """1 - check is the node has a right sibling (if so, that's some
         unreachable code)
         2 - check is the node is inside the finally clause of a try...finally
         block
         """
         # 1 - Is it right sibling ?
         self._check_unreachable(node)
         # 2 - Is it inside final body of a try...finally bloc ?
-        self._check_not_in_finally(node, 'break', (astng.For, astng.While,))
+        self._check_not_in_finally(node, 'break', (astroid.For, astroid.While,))
 
-    @check_messages('W0101')
+    @check_messages('unreachable', 'old-raise-syntax')
     def visit_raise(self, node):
-        """check is the node has a right sibling (if so, that's some unreachable
+        """check if the node has a right sibling (if so, that's some unreachable
         code)
         """
         self._check_unreachable(node)
+        if sys.version_info >= (3, 0):
+            return
+        if node.exc is not None and node.inst is not None and node.tback is None:
+            self.add_message('old-raise-syntax', node=node)
 
-    @check_messages('W0122')
+    @check_messages('exec-used')
     def visit_exec(self, node):
         """just print a warning on exec statements"""
-        self.add_message('W0122', node=node)
+        self.add_message('exec-used', node=node)
 
-    @check_messages('W0141', 'W0142')
+    @check_messages('bad-builtin', 'star-args', 'eval-used',
+                    'exec-used', 'missing-reversed-argument',
+                    'bad-reversed-sequence')
     def visit_callfunc(self, node):
         """visit a CallFunc node -> check if this is not a blacklisted builtin
         call and check for * or ** use
         """
-        if isinstance(node.func, astng.Name):
+        if isinstance(node.func, astroid.Name):
             name = node.func.name
             # ignore the name if it's not a builtin (i.e. not defined in the
             # locals nor globals scope)
             if not (name in node.frame() or
                     name in node.root()):
+                if name == 'exec':
+                    self.add_message('exec-used', node=node)
+                elif name == 'reversed':
+                    self._check_reversed(node)
+                elif name == 'eval':
+                    self.add_message('eval-used', node=node)
                 if name in self.config.bad_functions:
-                    self.add_message('W0141', node=node, args=name)
+                    self.add_message('bad-builtin', node=node, args=name)
         if node.starargs or node.kwargs:
             scope = node.scope()
-            if isinstance(scope, astng.Function):
+            if isinstance(scope, astroid.Function):
                 toprocess = [(n, vn) for (n, vn) in ((node.starargs, scope.args.vararg),
                                                      (node.kwargs, scope.args.kwarg)) if n]
                 if toprocess:
                     for cfnode, fargname in toprocess[:]:
                         if getattr(cfnode, 'name', None) == fargname:
                             toprocess.remove((cfnode, fargname))
                     if not toprocess:
-                        return # W0142 can be skipped
-            self.add_message('W0142', node=node.func)
+                        return # star-args can be skipped
+            self.add_message('star-args', node=node.func)
 
-    @check_messages('W0199')
+    @check_messages('assert-on-tuple')
     def visit_assert(self, node):
         """check the use of an assert statement on a tuple."""
-        if node.fail is None and isinstance(node.test, astng.Tuple) and \
-           len(node.test.elts) == 2:
-             self.add_message('W0199', line=node.fromlineno, node=node)
+        if node.fail is None and isinstance(node.test, astroid.Tuple) and \
+                len(node.test.elts) == 2:
+            self.add_message('assert-on-tuple', node=node)
 
-    @check_messages('W0109')
+    @check_messages('duplicate-key')
     def visit_dict(self, node):
         """check duplicate key in dictionary"""
         keys = set()
-        for k, v in node.items:
-            if isinstance(k, astng.Const):
+        for k, _ in node.items:
+            if isinstance(k, astroid.Const):
                 key = k.value
                 if key in keys:
-                    self.add_message('W0109', node=node, args=key)
+                    self.add_message('duplicate-key', node=node, args=key)
                 keys.add(key)
 
     def visit_tryfinally(self, node):
         """update try...finally flag"""
         self._tryfinallys.append(node)
 
     def leave_tryfinally(self, node):
         """update try...finally flag"""
         self._tryfinallys.pop()
 
     def _check_unreachable(self, node):
         """check unreachable code"""
         unreach_stmt = node.next_sibling()
         if unreach_stmt is not None:
-            self.add_message('W0101', node=unreach_stmt)
+            self.add_message('unreachable', node=unreach_stmt)
 
     def _check_not_in_finally(self, node, node_name, breaker_classes=()):
         """check that a node is not inside a finally clause of a
         try...finally statement.
         If we found before a try...finally bloc a parent which its type is
         in breaker_classes, we skip the whole check."""
         # if self._tryfinallys is empty, we're not a in try...finally bloc
         if not self._tryfinallys:
             return
         # the node could be a grand-grand...-children of the try...finally
         _parent = node.parent
         _node = node
         while _parent and not isinstance(_parent, breaker_classes):
             if hasattr(_parent, 'finalbody') and _node in _parent.finalbody:
-                self.add_message('W0150', node=node, args=node_name)
+                self.add_message('lost-exception', node=node, args=node_name)
                 return
             _node = _parent
             _parent = _node.parent
 
+    def _check_reversed(self, node):
+        """ check that the argument to `reversed` is a sequence """
+        try:
+            argument = safe_infer(get_argument_from_call(node, position=0))
+        except NoSuchArgumentError:
+            self.add_message('missing-reversed-argument', node=node)
+        else:
+            if argument is astroid.YES:
+                return
+            if argument is None:
+                # nothing was infered
+                # try to see if we have iter()
+                if isinstance(node.args[0], astroid.CallFunc):
+                    try:
+                        func = node.args[0].func.infer().next()
+                    except InferenceError:
+                        return
+                    if (getattr(func, 'name', None) == 'iter' and
+                            is_builtin_object(func)):
+                        self.add_message('bad-reversed-sequence', node=node)
+                return
 
+            if isinstance(argument, astroid.Instance):
+                if (argument._proxied.name == 'dict' and
+                        is_builtin_object(argument._proxied)):
+                    self.add_message('bad-reversed-sequence', node=node)
+                    return
+                elif any(ancestor.name == 'dict' and is_builtin_object(ancestor)
+                         for ancestor in argument._proxied.ancestors()):
+                    # mappings aren't accepted by reversed()
+                    self.add_message('bad-reversed-sequence', node=node)
+                    return
+
+                for methods in REVERSED_METHODS:
+                    for meth in methods:
+                        try:
+                            argument.getattr(meth)
+                        except astroid.NotFoundError:
+                            break
+                    else:
+                        break
+                else:
+                    # check if it is a .deque. It doesn't seem that
+                    # we can retrieve special methods
+                    # from C implemented constructs
+                    if argument._proxied.qname().endswith(".deque"):
+                        return
+                    self.add_message('bad-reversed-sequence', node=node)
+            elif not isinstance(argument, (astroid.List, astroid.Tuple)):
+                # everything else is not a proper sequence for reversed()
+                self.add_message('bad-reversed-sequence', node=node)
+
+_NAME_TYPES = {
+    'module': (MOD_NAME_RGX, 'module'),
+    'const': (CONST_NAME_RGX, 'constant'),
+    'class': (CLASS_NAME_RGX, 'class'),
+    'function': (DEFAULT_NAME_RGX, 'function'),
+    'method': (DEFAULT_NAME_RGX, 'method'),
+    'attr': (DEFAULT_NAME_RGX, 'attribute'),
+    'argument': (DEFAULT_NAME_RGX, 'argument'),
+    'variable': (DEFAULT_NAME_RGX, 'variable'),
+    'class_attribute': (CLASS_ATTRIBUTE_RGX, 'class attribute'),
+    'inlinevar': (COMP_VAR_RGX, 'inline iteration'),
+}
+
+def _create_naming_options():
+    name_options = []
+    for name_type, (rgx, human_readable_name) in _NAME_TYPES.iteritems():
+        name_type = name_type.replace('_', '-')
+        name_options.append((
+            '%s-rgx' % (name_type,),
+            {'default': rgx, 'type': 'regexp', 'metavar': '<regexp>',
+             'help': 'Regular expression matching correct %s names' % (human_readable_name,)}))
+        name_options.append((
+            '%s-name-hint' % (name_type,),
+            {'default': rgx.pattern, 'type': 'string', 'metavar': '<string>',
+             'help': 'Naming hint for %s names' % (human_readable_name,)}))
+    return tuple(name_options)
 
 class NameChecker(_BasicChecker):
     msgs = {
-    'C0102': ('Black listed name "%s"',
-              'Used when the name is listed in the black list (unauthorized \
-              names).'),
-    'C0103': ('Invalid name "%s" (should match %s)',
-              'Used when the name doesn\'t match the regular expression \
-              associated to its type (constant, variable, class...).'),
+        'C0102': ('Black listed name "%s"',
+                  'blacklisted-name',
+                  'Used when the name is listed in the black list (unauthorized '
+                  'names).'),
+        'C0103': ('Invalid %s name "%s"%s',
+                  'invalid-name',
+                  'Used when the name doesn\'t match the regular expression '
+                  'associated to its type (constant, variable, class...).'),
+    }
 
-    }
-    options = (('module-rgx',
-                {'default' : MOD_NAME_RGX,
-                 'type' :'regexp', 'metavar' : '<regexp>',
-                 'help' : 'Regular expression which should only match correct '
-                          'module names'}
-                ),
-               ('const-rgx',
-                {'default' : CONST_NAME_RGX,
-                 'type' :'regexp', 'metavar' : '<regexp>',
-                 'help' : 'Regular expression which should only match correct '
-                          'module level names'}
-                ),
-               ('class-rgx',
-                {'default' : CLASS_NAME_RGX,
-                 'type' :'regexp', 'metavar' : '<regexp>',
-                 'help' : 'Regular expression which should only match correct '
-                          'class names'}
-                ),
-               ('function-rgx',
-                {'default' : DEFAULT_NAME_RGX,
-                 'type' :'regexp', 'metavar' : '<regexp>',
-                 'help' : 'Regular expression which should only match correct '
-                          'function names'}
-                ),
-               ('method-rgx',
-                {'default' : DEFAULT_NAME_RGX,
-                 'type' :'regexp', 'metavar' : '<regexp>',
-                 'help' : 'Regular expression which should only match correct '
-                          'method names'}
-                ),
-               ('attr-rgx',
-                {'default' : DEFAULT_NAME_RGX,
-                 'type' :'regexp', 'metavar' : '<regexp>',
-                 'help' : 'Regular expression which should only match correct '
-                          'instance attribute names'}
-                ),
-               ('argument-rgx',
-                {'default' : DEFAULT_NAME_RGX,
-                 'type' :'regexp', 'metavar' : '<regexp>',
-                 'help' : 'Regular expression which should only match correct '
-                          'argument names'}),
-               ('variable-rgx',
-                {'default' : DEFAULT_NAME_RGX,
-                 'type' :'regexp', 'metavar' : '<regexp>',
-                 'help' : 'Regular expression which should only match correct '
-                          'variable names'}
-                ),
-               ('inlinevar-rgx',
-                {'default' : COMP_VAR_RGX,
-                 'type' :'regexp', 'metavar' : '<regexp>',
-                 'help' : 'Regular expression which should only match correct '
-                          'list comprehension / generator expression variable \
-                          names'}
-                ),
-               # XXX use set
-               ('good-names',
+    options = (('good-names',
                 {'default' : ('i', 'j', 'k', 'ex', 'Run', '_'),
                  'type' :'csv', 'metavar' : '<names>',
                  'help' : 'Good variable names which should always be accepted,'
                           ' separated by a comma'}
-                ),
+               ),
                ('bad-names',
                 {'default' : ('foo', 'bar', 'baz', 'toto', 'tutu', 'tata'),
                  'type' :'csv', 'metavar' : '<names>',
                  'help' : 'Bad variable names which should always be refused, '
                           'separated by a comma'}
-                ),
-               )
+               ),
+               ('name-group',
+                {'default' : (),
+                 'type' :'csv', 'metavar' : '<name1:name2>',
+                 'help' : ('Colon-delimited sets of names that determine each'
+                           ' other\'s naming style when the name regexes'
+                           ' allow several styles.')}
+               ),
+               ('include-naming-hint',
+                {'default': False, 'type' : 'yn', 'metavar' : '<y_or_n>',
+                 'help': 'Include a hint for the correct naming format with invalid-name'}
+               ),
+              ) + _create_naming_options()
+
+
+    def __init__(self, linter):
+        _BasicChecker.__init__(self, linter)
+        self._name_category = {}
+        self._name_group = {}
 
     def open(self):
         self.stats = self.linter.add_stats(badname_module=0,
                                            badname_class=0, badname_function=0,
                                            badname_method=0, badname_attr=0,
                                            badname_const=0,
                                            badname_variable=0,
                                            badname_inlinevar=0,
-                                           badname_argument=0)
+                                           badname_argument=0,
+                                           badname_class_attribute=0)
+        for group in self.config.name_group:
+            for name_type in group.split(':'):
+                self._name_group[name_type] = 'group_%s' % (group,)
 
-    @check_messages('C0102', 'C0103')
+    @check_messages('blacklisted-name', 'invalid-name')
     def visit_module(self, node):
         self._check_name('module', node.name.split('.')[-1], node)
 
-    @check_messages('C0102', 'C0103')
+    @check_messages('blacklisted-name', 'invalid-name')
     def visit_class(self, node):
         self._check_name('class', node.name, node)
-        for attr, anodes in node.instance_attrs.items():
-            self._check_name('attr', attr, anodes[0])
+        for attr, anodes in node.instance_attrs.iteritems():
+            if not list(node.instance_attr_ancestors(attr)):
+                self._check_name('attr', attr, anodes[0])
 
-    @check_messages('C0102', 'C0103')
+    @check_messages('blacklisted-name', 'invalid-name')
     def visit_function(self, node):
-        self._check_name(node.is_method() and 'method' or 'function',
+        # Do not emit any warnings if the method is just an implementation
+        # of a base class method.
+        if node.is_method() and overrides_a_method(node.parent.frame(), node.name):
+            return
+        self._check_name(_determine_function_name_type(node),
                          node.name, node)
-        # check arguments name
+        # Check argument names
         args = node.args.args
         if args is not None:
             self._recursive_check_names(args, node)
 
-    @check_messages('C0102', 'C0103')
+    @check_messages('blacklisted-name', 'invalid-name')
+    def visit_global(self, node):
+        for name in node.names:
+            self._check_name('const', name, node)
+
+    @check_messages('blacklisted-name', 'invalid-name')
     def visit_assname(self, node):
         """check module level assigned names"""
         frame = node.frame()
         ass_type = node.ass_type()
-        if isinstance(ass_type, (astng.Comprehension, astng.Comprehension)):
+        if isinstance(ass_type, astroid.Comprehension):
             self._check_name('inlinevar', node.name, node)
-        elif isinstance(frame, astng.Module):
-            if isinstance(ass_type, astng.Assign) and not in_loop(ass_type):
-                self._check_name('const', node.name, node)
-            elif isinstance(ass_type, astng.ExceptHandler):
+        elif isinstance(frame, astroid.Module):
+            if isinstance(ass_type, astroid.Assign) and not in_loop(ass_type):
+                if isinstance(safe_infer(ass_type.value), astroid.Class):
+                    self._check_name('class', node.name, node)
+                else:
+                    self._check_name('const', node.name, node)
+            elif isinstance(ass_type, astroid.ExceptHandler):
                 self._check_name('variable', node.name, node)
-        elif isinstance(frame, astng.Function):
+        elif isinstance(frame, astroid.Function):
             # global introduced variable aren't in the function locals
-            if node.name in frame:
+            if node.name in frame and node.name not in frame.argnames():
                 self._check_name('variable', node.name, node)
+        elif isinstance(frame, astroid.Class):
+            if not list(frame.local_attr_ancestors(node.name)):
+                self._check_name('class_attribute', node.name, node)
 
     def _recursive_check_names(self, args, node):
         """check names in a possibly recursive list <arg>"""
         for arg in args:
-            if isinstance(arg, astng.AssName):
+            if isinstance(arg, astroid.AssName):
                 self._check_name('argument', arg.name, node)
             else:
                 self._recursive_check_names(arg.elts, node)
 
+    def _find_name_group(self, node_type):
+        return self._name_group.get(node_type, node_type)
+
+    def _is_multi_naming_match(self, match):
+        return (match is not None and
+                match.lastgroup is not None and
+                match.lastgroup not in EXEMPT_NAME_CATEGORIES)
+
     def _check_name(self, node_type, name, node):
         """check for a name using the type's regexp"""
         if is_inside_except(node):
             clobbering, _ = clobber_in_except(node)
             if clobbering:
                 return
-
         if name in self.config.good_names:
             return
         if name in self.config.bad_names:
             self.stats['badname_' + node_type] += 1
-            self.add_message('C0102', node=node, args=name)
+            self.add_message('blacklisted-name', node=node, args=name)
             return
         regexp = getattr(self.config, node_type + '_rgx')
-        if regexp.match(name) is None:
-            self.add_message('C0103', node=node, args=(name, regexp.pattern))
+        match = regexp.match(name)
+
+        if self._is_multi_naming_match(match):
+            name_group = self._find_name_group(node_type)
+            if name_group not in self._name_category:
+                self._name_category[name_group] = match.lastgroup
+            elif self._name_category[name_group] != match.lastgroup:
+                match = None
+
+        if match is None:
+            type_label = _NAME_TYPES[node_type][1]
+            hint = ''
+            if self.config.include_naming_hint:
+                hint = ' (hint: %s)' % (getattr(self.config, node_type + '_name_hint'))
+            self.add_message('invalid-name', node=node, args=(type_label, name, hint))
             self.stats['badname_' + node_type] += 1
 
 
 class DocStringChecker(_BasicChecker):
     msgs = {
-    'C0111': ('Missing docstring', # W0131
-              'Used when a module, function, class or method has no docstring.\
-              Some special methods like __init__ doesn\'t necessary require a \
-              docstring.'),
-    'C0112': ('Empty docstring', # W0132
-              'Used when a module, function, class or method has an empty \
-              docstring (it would be too easy ;).'),
-    }
+        'C0111': ('Missing %s docstring', # W0131
+                  'missing-docstring',
+                  'Used when a module, function, class or method has no docstring.'
+                  'Some special methods like __init__ doesn\'t necessary require a '
+                  'docstring.'),
+        'C0112': ('Empty %s docstring', # W0132
+                  'empty-docstring',
+                  'Used when a module, function, class or method has an empty '
+                  'docstring (it would be too easy ;).'),
+        }
     options = (('no-docstring-rgx',
                 {'default' : NO_REQUIRED_DOC_RGX,
                  'type' : 'regexp', 'metavar' : '<regexp>',
                  'help' : 'Regular expression which should only match '
-                          'functions or classes name which do not require a '
-                          'docstring'}
-                ),
-               )
+                          'function or class names that do not require a '
+                          'docstring.'}
+               ),
+               ('docstring-min-length',
+                {'default' : -1,
+                 'type' : 'int', 'metavar' : '<int>',
+                 'help': ('Minimum line length for functions/classes that'
+                          ' require docstrings, shorter ones are exempt.')}
+               ),
+              )
+
 
     def open(self):
         self.stats = self.linter.add_stats(undocumented_module=0,
                                            undocumented_function=0,
                                            undocumented_method=0,
                                            undocumented_class=0)
-
+    @check_messages('missing-docstring', 'empty-docstring')
     def visit_module(self, node):
         self._check_docstring('module', node)
 
+    @check_messages('missing-docstring', 'empty-docstring')
     def visit_class(self, node):
         if self.config.no_docstring_rgx.match(node.name) is None:
             self._check_docstring('class', node)
-
+    @check_messages('missing-docstring', 'empty-docstring')
     def visit_function(self, node):
         if self.config.no_docstring_rgx.match(node.name) is None:
             ftype = node.is_method() and 'method' or 'function'
-            if isinstance(node.parent.frame(), astng.Class):
+            if isinstance(node.parent.frame(), astroid.Class):
                 overridden = False
                 # check if node is from a method overridden by its ancestor
                 for ancestor in node.parent.frame().ancestors():
                     if node.name in ancestor and \
-                       isinstance(ancestor[node.name], astng.Function):
+                       isinstance(ancestor[node.name], astroid.Function):
                         overridden = True
                         break
-                if not overridden:
-                    self._check_docstring(ftype, node)
+                self._check_docstring(ftype, node,
+                                      report_missing=not overridden)
             else:
                 self._check_docstring(ftype, node)
 
-    def _check_docstring(self, node_type, node):
+    def _check_docstring(self, node_type, node, report_missing=True):
         """check the node has a non empty docstring"""
         docstring = node.doc
         if docstring is None:
+            if not report_missing:
+                return
+            if node.body:
+                lines = node.body[-1].lineno - node.body[0].lineno + 1
+            else:
+                lines = 0
+            max_lines = self.config.docstring_min_length
+
+            if node_type != 'module' and max_lines > -1 and lines < max_lines:
+                return
             self.stats['undocumented_'+node_type] += 1
-            self.add_message('C0111', node=node)
+            if (node.body and isinstance(node.body[0], astroid.Discard) and
+                isinstance(node.body[0].value, astroid.CallFunc)):
+                # Most likely a string with a format call. Let's see.
+                func = safe_infer(node.body[0].value.func)
+                if (isinstance(func, astroid.BoundMethod)
+                    and isinstance(func.bound, astroid.Instance)):
+                    # Strings in Python 3, others in Python 2.
+                    if PY3K and func.bound.name == 'str':
+                        return
+                    elif func.bound.name in ('str', 'unicode', 'bytes'):
+                        return
+            self.add_message('missing-docstring', node=node, args=(node_type,))
         elif not docstring.strip():
             self.stats['undocumented_'+node_type] += 1
-            self.add_message('C0112', node=node)
+            self.add_message('empty-docstring', node=node, args=(node_type,))
 
 
 class PassChecker(_BasicChecker):
-    """check is the pass statement is really necessary"""
+    """check if the pass statement is really necessary"""
     msgs = {'W0107': ('Unnecessary pass statement',
+                      'unnecessary-pass',
                       'Used when a "pass" statement that can be avoided is '
-                      'encountered.)'),
-            }
-
+                      'encountered.'),
+           }
+    @check_messages('unnecessary-pass')
     def visit_pass(self, node):
         if len(node.parent.child_sequence(node)) > 1:
-            self.add_message('W0107', node=node)
+            self.add_message('unnecessary-pass', node=node)
+
+
+class LambdaForComprehensionChecker(_BasicChecker):
+    """check for using a lambda where a comprehension would do.
+
+    See <http://www.artima.com/weblogs/viewpost.jsp?thread=98196>
+    where GvR says comprehensions would be clearer.
+    """
+
+    msgs = {'W0110': ('map/filter on lambda could be replaced by comprehension',
+                      'deprecated-lambda',
+                      'Used when a lambda is the first argument to "map" or '
+                      '"filter". It could be clearer as a list '
+                      'comprehension or generator expression.',
+                      {'maxversion': (3, 0)}),
+           }
+
+    @check_messages('deprecated-lambda')
+    def visit_callfunc(self, node):
+        """visit a CallFunc node, check if map or filter are called with a
+        lambda
+        """
+        if not node.args:
+            return
+        if not isinstance(node.args[0], astroid.Lambda):
+            return
+        infered = safe_infer(node.func)
+        if (is_builtin_object(infered)
+                and infered.name in ['map', 'filter']):
+            self.add_message('deprecated-lambda', node=node)
 
 
 def register(linter):
     """required method to auto register this checker"""
     linter.register_checker(BasicErrorChecker(linter))
     linter.register_checker(BasicChecker(linter))
     linter.register_checker(NameChecker(linter))
     linter.register_checker(DocStringChecker(linter))
     linter.register_checker(PassChecker(linter))
+    linter.register_checker(LambdaForComprehensionChecker(linter))