Revert "Revert "pylint: upgrade to 1.3.1""

third_party/pylint/checkers/classes.py

-# Copyright (c) 2003-2011 LOGILAB S.A. (Paris, FRANCE).
+# Copyright (c) 2003-2014 LOGILAB S.A. (Paris, FRANCE).
 # 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.
 """classes checker for Python code
 """
 from __future__ import generators
 
-from logilab import astng
-from logilab.astng import YES, Instance, are_exclusive
+import sys
 
-from pylint.interfaces import IASTNGChecker
+import astroid
+from astroid import YES, Instance, are_exclusive, AssAttr, Class
+from astroid.bases import Generator
+
+from pylint.interfaces import IAstroidChecker
 from pylint.checkers import BaseChecker
-from pylint.checkers.utils import PYMETHODS, overrides_a_method, check_messages
+from pylint.checkers.utils import (
+    PYMETHODS, overrides_a_method, check_messages, is_attr_private,
+    is_attr_protected, node_frame_class, safe_infer)
+
+if sys.version_info >= (3, 0):
+    NEXT_METHOD = '__next__'
+else:
+    NEXT_METHOD = 'next'
+ITER_METHODS = ('__iter__', '__getitem__')
 
 def class_is_abstract(node):
     """return true if the given class node should be considered as an abstract
     class
     """
     for method in node.methods():
         if method.parent.frame() is node:
             if method.is_abstract(pass_is_abstract=False):
                 return True
     return False
 
 
 MSGS = {
     'F0202': ('Unable to check methods signature (%s / %s)',
+              'method-check-failed',
               'Used when PyLint has been unable to check methods signature \
               compatibility for an unexpected reason. Please report this kind \
               if you don\'t make sense of it.'),
 
-    'E0202': ('An attribute affected in %s line %s hide this method',
+    'E0202': ('An attribute defined in %s line %s hides this method',
+              'method-hidden',
               'Used when a class defines a method which is hidden by an '
               'instance attribute from an ancestor class or set by some '
               'client code.'),
     'E0203': ('Access to member %r before its definition line %s',
+              'access-member-before-definition',
               'Used when an instance member is accessed before it\'s actually\
               assigned.'),
     'W0201': ('Attribute %r defined outside __init__',
+              'attribute-defined-outside-init',
               'Used when an instance attribute is defined outside the __init__\
               method.'),
 
     'W0212': ('Access to a protected member %s of a client class', # E0214
+              'protected-access',
               'Used when a protected member (i.e. class member with a name \
               beginning with an underscore) is access outside the class or a \
               descendant of the class where it\'s defined.'),
 
     'E0211': ('Method has no argument',
+              'no-method-argument',
               'Used when a method which should have the bound instance as \
               first argument has no argument defined.'),
     'E0213': ('Method should have "self" as first argument',
+              'no-self-argument',
               'Used when a method has an attribute different the "self" as\
               first argument. This is considered as an error since this is\
               a so common convention that you shouldn\'t break it!'),
-    'C0202': ('Class method should have %s as first argument', # E0212
-              'Used when a class method has an attribute different than "cls"\
-              as first argument, to easily differentiate them from regular \
-              instance methods.'),
-    'C0203': ('Metaclass method should have "mcs" as first argument', # E0214
-              'Used when a metaclass method has an attribute different the \
-              "mcs" as first argument.'),
+    'C0202': ('Class method %s should have %s as first argument', # E0212
+              'bad-classmethod-argument',
+              'Used when a class method has a first argument named differently '
+              'than the value specified in valid-classmethod-first-arg option '
+              '(default to "cls"), recommended to easily differentiate them '
+              'from regular instance methods.'),
+    'C0203': ('Metaclass method %s should have %s as first argument', # E0214
+              'bad-mcs-method-argument',
+              'Used when a metaclass method has a first agument named '
+              'differently than the value specified in valid-classmethod-first'
+              '-arg option (default to "cls"), recommended to easily '
+              'differentiate them from regular instance methods.'),
+    'C0204': ('Metaclass class method %s should have %s as first argument',
+              'bad-mcs-classmethod-argument',
+              'Used when a metaclass class method has a first argument named '
+              'differently than the value specified in valid-metaclass-'
+              'classmethod-first-arg option (default to "mcs"), recommended to '
+              'easily differentiate them from regular instance methods.'),
 
     'W0211': ('Static method with %r as first argument',
-              'Used when a static method has "self" or "cls" as first argument.'
-              ),
+              'bad-staticmethod-argument',
+              'Used when a static method has "self" or a value specified in '
+              'valid-classmethod-first-arg option or '
+              'valid-metaclass-classmethod-first-arg option as first argument.'
+             ),
     'R0201': ('Method could be a function',
+              'no-self-use',
               'Used when a method doesn\'t use its bound instance, and so could\
               be written as a function.'
-              ),
+             ),
 
     'E0221': ('Interface resolved to %s is not a class',
+              'interface-is-not-class',
               'Used when a class claims to implement an interface which is not \
               a class.'),
     'E0222': ('Missing method %r from %s interface',
+              'missing-interface-method',
               'Used when a method declared in an interface is missing from a \
               class implementing this interface'),
     'W0221': ('Arguments number differs from %s method',
+              'arguments-differ',
               'Used when a method has a different number of arguments than in \
               the implemented interface or in an overridden method.'),
     'W0222': ('Signature differs from %s method',
+              'signature-differs',
               'Used when a method signature is different than in the \
               implemented interface or in an overridden method.'),
     'W0223': ('Method %r is abstract in class %r but is not overridden',
+              'abstract-method',
               'Used when an abstract method (i.e. raise NotImplementedError) is \
               not overridden in concrete class.'
-              ),
+             ),
     'F0220': ('failed to resolve interfaces implemented by %s (%s)', # W0224
+              'unresolved-interface',
               'Used when a PyLint as failed to find interfaces implemented by \
                a class'),
 
 
     'W0231': ('__init__ method from base class %r is not called',
+              'super-init-not-called',
               'Used when an ancestor class method has an __init__ method \
               which is not called by a derived class.'),
     'W0232': ('Class has no __init__ method',
+              'no-init',
               'Used when a class has no __init__ method, neither its parent \
               classes.'),
     'W0233': ('__init__ method from a non direct base class %r is called',
+              'non-parent-init-called',
               'Used when an __init__ method is called on a class which is not \
               in the direct ancestors for the analysed class.'),
+    'W0234': ('__iter__ returns non-iterator',
+              'non-iterator-returned',
+              'Used when an __iter__ method returns something which is not an \
+               iterable (i.e. has no `%s` method)' % NEXT_METHOD),
+    'E0235': ('__exit__ must accept 3 arguments: type, value, traceback',
+              'bad-context-manager',
+              'Used when the __exit__ special method, belonging to a \
+               context manager, does not accept 3 arguments \
+               (type, value, traceback).'),
+    'E0236': ('Invalid object %r in __slots__, must contain '
+              'only non empty strings',
+              'invalid-slots-object',
+              'Used when an invalid (non-string) object occurs in __slots__.'),
+    'E0237': ('Assigning to attribute %r not defined in class slots',
+              'assigning-non-slot',
+              'Used when assigning to an attribute not defined '
+              'in the class slots.'),
+    'E0238': ('Invalid __slots__ object',
+              'invalid-slots',
+              'Used when an invalid __slots__ is found in class. '
+              'Only a string, an iterable or a sequence is permitted.')
+
 
     }
 
 
 class ClassChecker(BaseChecker):
     """checks for :
     * methods without self as first argument
     * overridden methods signature
     * access only to existent members via self
     * attributes not defined in the __init__ method
     * supported interfaces implementation
     * unreachable code
     """
 
-    __implements__ = (IASTNGChecker,)
+    __implements__ = (IAstroidChecker,)
 
     # configuration section name
     name = 'classes'
     # messages
     msgs = MSGS
     priority = -2
     # configuration options
     options = (('ignore-iface-methods',
                 {'default' : (#zope interface
-        'isImplementedBy', 'deferred', 'extends', 'names',
-        'namesAndDescriptions', 'queryDescriptionFor',  'getBases',
-        'getDescriptionFor', 'getDoc', 'getName', 'getTaggedValue',
-        'getTaggedValueTags', 'isEqualOrExtendedBy', 'setTaggedValue',
-        'isImplementedByInstancesOf',
-        # twisted
-        'adaptWith',
-        # logilab.common interface
-        'is_implemented_by'),
+                    'isImplementedBy', 'deferred', 'extends', 'names',
+                    'namesAndDescriptions', 'queryDescriptionFor', 'getBases',
+                    'getDescriptionFor', 'getDoc', 'getName', 'getTaggedValue',
+                    'getTaggedValueTags', 'isEqualOrExtendedBy', 'setTaggedValue',
+                    'isImplementedByInstancesOf',
+                    # twisted
+                    'adaptWith',
+                    # logilab.common interface
+                    'is_implemented_by'),
                  'type' : 'csv',
                  'metavar' : '<method names>',
                  'help' : '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.'}
-                ),
-
+               ),
                ('defining-attr-methods',
                 {'default' : ('__init__', '__new__', 'setUp'),
                  'type' : 'csv',
                  'metavar' : '<method names>',
                  'help' : 'List of method names used to declare (i.e. assign) \
 instance attributes.'}
-                ),
+               ),
                ('valid-classmethod-first-arg',
                 {'default' : ('cls',),
                  'type' : 'csv',
                  'metavar' : '<argument names>',
                  'help' : 'List of valid names for the first argument in \
 a class method.'}
-                ),
-
-               )
+               ),
+               ('valid-metaclass-classmethod-first-arg',
+                {'default' : ('mcs',),
+                 'type' : 'csv',
+                 'metavar' : '<argument names>',
+                 'help' : 'List of valid names for the first argument in \
+a metaclass class method.'}
+               ),
+              )
 
     def __init__(self, linter=None):
         BaseChecker.__init__(self, linter)
         self._accessed = []
         self._first_attrs = []
         self._meth_could_be_func = None
 
     def visit_class(self, node):
         """init visit variable _accessed and check interfaces
         """
         self._accessed.append({})
         self._check_bases_classes(node)
         self._check_interfaces(node)
         # if not an interface, exception, metaclass
         if node.type == 'class':
             try:
                 node.local_attr('__init__')
-            except astng.NotFoundError:
-                self.add_message('W0232', args=node, node=node)
+            except astroid.NotFoundError:
+                self.add_message('no-init', args=node, node=node)
+        self._check_slots(node)
 
-    @check_messages('E0203', 'W0201')
+    @check_messages('access-member-before-definition', 'attribute-defined-outside-init')
     def leave_class(self, cnode):
         """close a class node:
         check that instance attributes are defined in __init__ and check
         access to existent members
         """
         # check access to existent members on non metaclass classes
         accessed = self._accessed.pop()
         if cnode.type != 'metaclass':
             self._check_accessed_members(cnode, accessed)
         # checks attributes are defined in an allowed method such as __init__
-        if 'W0201' not in self.active_msgs:
+        if not self.linter.is_message_enabled('attribute-defined-outside-init'):
             return
         defining_methods = self.config.defining_attr_methods
-        for attr, nodes in cnode.instance_attrs.items():
+        current_module = cnode.root()
+        for attr, nodes in cnode.instance_attrs.iteritems():
+            # skip nodes which are not in the current module and it may screw up
+            # the output, while it's not worth it
             nodes = [n for n in nodes if not
-                    isinstance(n.statement(), (astng.Delete, astng.AugAssign))]
+                     isinstance(n.statement(), (astroid.Delete, astroid.AugAssign))
+                     and n.root() is current_module]
             if not nodes:
                 continue # error detected by typechecking
-            attr_defined = False
             # check if any method attr is defined in is a defining method
-            for node in nodes:
-                if node.frame().name in defining_methods:
-                    attr_defined = True
-            if not attr_defined:
-                # check attribute is defined in a parent's __init__
-                for parent in cnode.instance_attr_ancestors(attr):
-                    attr_defined = False
-                    # check if any parent method attr is defined in is a defining method
-                    for node in parent.instance_attrs[attr]:
-                        if node.frame().name in defining_methods:
-                            attr_defined = True
-                    if attr_defined:
-                        # we're done :)
-                        break
-                else:
-                    # check attribute is defined as a class attribute
-                    try:
-                        cnode.local_attr(attr)
-                    except astng.NotFoundError:
-                        self.add_message('W0201', args=attr, node=node)
+            if any(node.frame().name in defining_methods
+                   for node in nodes):
+                continue
+
+            # check attribute is defined in a parent's __init__
+            for parent in cnode.instance_attr_ancestors(attr):
+                attr_defined = False
+                # check if any parent method attr is defined in is a defining method
+                for node in parent.instance_attrs[attr]:
+                    if node.frame().name in defining_methods:
+                        attr_defined = True
+                if attr_defined:
+                    # we're done :)
+                    break
+            else:
+                # check attribute is defined as a class attribute
+                try:
+                    cnode.local_attr(attr)
+                except astroid.NotFoundError:
+                    for node in nodes:
+                        if node.frame().name not in defining_methods:
+                            self.add_message('attribute-defined-outside-init',
+                                             args=attr, node=node)
 
     def visit_function(self, node):
         """check method arguments, overriding"""
         # ignore actual functions
         if not node.is_method():
             return
         klass = node.parent.frame()
         self._meth_could_be_func = True
         # check first argument is self if this is actually a method
         self._check_first_arg_for_type(node, klass.type == 'metaclass')
         if node.name == '__init__':
             self._check_init(node)
             return
         # check signature if the method overloads inherited method
         for overridden in klass.local_attr_ancestors(node.name):
-            # get astng for the searched method
+            # get astroid for the searched method
             try:
                 meth_node = overridden[node.name]
             except KeyError:
                 # we have found the method but it's not in the local
                 # dictionary.
-                # This may happen with astng build from living objects
+                # This may happen with astroid build from living objects
                 continue
-            if not isinstance(meth_node, astng.Function):
+            if not isinstance(meth_node, astroid.Function):
                 continue
             self._check_signature(node, meth_node, 'overridden')
             break
-        # check if the method overload an attribute
+        if node.decorators:
+            for decorator in node.decorators.nodes:
+                if isinstance(decorator, astroid.Getattr) and \
+                        decorator.attrname in ('getter', 'setter', 'deleter'):
+                    # attribute affectation will call this method, not hiding it
+                    return
+                if isinstance(decorator, astroid.Name) and decorator.name == 'property':
+                    # attribute affectation will either call a setter or raise
+                    # an attribute error, anyway not hiding the function
+                    return
+        # check if the method is hidden by an attribute
         try:
             overridden = klass.instance_attr(node.name)[0] # XXX
-            args = (overridden.root().name, overridden.fromlineno)
-            self.add_message('E0202', args=args, node=node)
-        except astng.NotFoundError:
+            overridden_frame = overridden.frame()
+            if (isinstance(overridden_frame, astroid.Function)
+                    and overridden_frame.type == 'method'):
+                overridden_frame = overridden_frame.parent.frame()
+            if (isinstance(overridden_frame, Class)
+                    and klass._is_subtype_of(overridden_frame.qname())):
+                args = (overridden.root().name, overridden.fromlineno)
+                self.add_message('method-hidden', args=args, node=node)
+        except astroid.NotFoundError:
             pass
 
+        # check non-iterators in __iter__
+        if node.name == '__iter__':
+            self._check_iter(node)
+        elif node.name == '__exit__':
+            self._check_exit(node)
+
+    def _check_slots(self, node):
+        if '__slots__' not in node.locals:
+            return
+        for slots in node.igetattr('__slots__'):
+            # check if __slots__ is a valid type
+            for meth in ITER_METHODS:
+                try:
+                    slots.getattr(meth)
+                    break
+                except astroid.NotFoundError:
+                    continue
+            else:
+                self.add_message('invalid-slots', node=node)
+                continue
+
+            if isinstance(slots, astroid.Const):
+                # a string, ignore the following checks
+                continue
+            if not hasattr(slots, 'itered'):
+                # we can't obtain the values, maybe a .deque?
+                continue
+
+            if isinstance(slots, astroid.Dict):
+                values = [item[0] for item in slots.items]
+            else:
+                values = slots.itered()
+            if values is YES:
+                return
+
+            for elt in values:
+                try:
+                    self._check_slots_elt(elt)
+                except astroid.InferenceError:
+                    continue
+
+    def _check_slots_elt(self, elt):
+        for infered in elt.infer():
+            if infered is YES:
+                continue
+            if (not isinstance(infered, astroid.Const) or
+                    not isinstance(infered.value, str)):
+                self.add_message('invalid-slots-object',
+                                 args=infered.as_string(),
+                                 node=elt)
+                continue
+            if not infered.value:
+                self.add_message('invalid-slots-object',
+                                 args=infered.as_string(),
+                                 node=elt)
+
+    def _check_iter(self, node):
+        try:
+            infered = node.infer_call_result(node)
+        except astroid.InferenceError:
+            return
+
+        for infered_node in infered:
+            if (infered_node is YES
+                    or isinstance(infered_node, Generator)):
+                continue
+            if isinstance(infered_node, astroid.Instance):
+                try:
+                    infered_node.local_attr(NEXT_METHOD)
+                except astroid.NotFoundError:
+                    self.add_message('non-iterator-returned',
+                                     node=node)
+                    break
+
+    def _check_exit(self, node):
+        positional = sum(1 for arg in node.args.args if arg.name != 'self')
+        if positional < 3 and not node.args.vararg:
+            self.add_message('bad-context-manager',
+                             node=node)
+        elif positional > 3:
+            self.add_message('bad-context-manager',
+                             node=node)
+
     def leave_function(self, node):
         """on method node, check if this method couldn't be a function
 
         ignore class, static and abstract methods, initializer,
         methods overridden from a parent class and any
         kind of method defined in an interface for this warning
         """
         if node.is_method():
             if node.args.args is not None:
                 self._first_attrs.pop()
-            if 'R0201' not in self.active_msgs:
+            if not self.linter.is_message_enabled('no-self-use'):
                 return
             class_node = node.parent.frame()
             if (self._meth_could_be_func and node.type == 'method'
-                and not node.name in PYMETHODS
-                and not (node.is_abstract() or
-                         overrides_a_method(class_node, node.name))
-                and class_node.type != 'interface'):
-                self.add_message('R0201', node=node)
+                    and not node.name in PYMETHODS
+                    and not (node.is_abstract() or
+                             overrides_a_method(class_node, node.name))
+                    and class_node.type != 'interface'):
+                self.add_message('no-self-use', node=node)
 
     def visit_getattr(self, node):
         """check if the getattr is an access to a class member
         if so, register it. Also check for access to protected
         class member from outside its class (but ignore __special__
         methods)
         """
         attrname = node.attrname
-        if self._first_attrs and isinstance(node.expr, astng.Name) and \
-               node.expr.name == self._first_attrs[-1]:
+        # Check self
+        if self.is_first_attr(node):
             self._accessed[-1].setdefault(attrname, []).append(node)
             return
-        if 'W0212' not in self.active_msgs:
+        if not self.linter.is_message_enabled('protected-access'):
             return
-        if attrname[0] == '_' and not attrname == '_' and not (
-             attrname.startswith('__') and attrname.endswith('__')):
-            # XXX move this in a reusable function
-            klass = node.frame()
-            while klass is not None and not isinstance(klass, astng.Class):
-                if klass.parent is None:
-                    klass = None
-                else:
-                    klass = klass.parent.frame()
+
+        self._check_protected_attribute_access(node)
+
+    def visit_assattr(self, node):
+        if isinstance(node.ass_type(), astroid.AugAssign) and self.is_first_attr(node):
+            self._accessed[-1].setdefault(node.attrname, []).append(node)
+        self._check_in_slots(node)
+
+    def _check_in_slots(self, node):
+        """ Check that the given assattr node
+        is defined in the class slots.
+        """
+        infered = safe_infer(node.expr)
+        if infered and isinstance(infered, Instance):
+            klass = infered._proxied
+            if '__slots__' not in klass.locals or not klass.newstyle:
+                return
+
+            slots = klass.slots()
+            # If any ancestor doesn't use slots, the slots
+            # defined for this class are superfluous.
+            if any('__slots__' not in ancestor.locals and
+                   ancestor.name != 'object'
+                   for ancestor in klass.ancestors()):
+                return
+
+            if not any(slot.value == node.attrname for slot in slots):
+                # If we have a '__dict__' in slots, then
+                # assigning any name is valid.
+                if not any(slot.value == '__dict__' for slot in slots):
+                    self.add_message('assigning-non-slot',
+                                     args=(node.attrname, ), node=node)
+
+    @check_messages('protected-access')
+    def visit_assign(self, assign_node):
+        node = assign_node.targets[0]
+        if not isinstance(node, AssAttr):
+            return
+
+        if self.is_first_attr(node):
+            return
+
+        self._check_protected_attribute_access(node)
+
+    def _check_protected_attribute_access(self, node):
+        '''Given an attribute access node (set or get), check if attribute
+        access is legitimate. Call _check_first_attr with node before calling
+        this method. Valid cases are:
+        * self._attr in a method or cls._attr in a classmethod. Checked by
+        _check_first_attr.
+        * Klass._attr inside "Klass" class.
+        * Klass2._attr inside "Klass" class when Klass2 is a base class of
+            Klass.
+        '''
+        attrname = node.attrname
+
+        if is_attr_protected(attrname):
+
+            klass = node_frame_class(node)
+
             # XXX infer to be more safe and less dirty ??
             # in classes, check we are not getting a parent method
             # through the class object or through super
             callee = node.expr.as_string()
-            if klass is None or not (callee == klass.name or
-                callee in klass.basenames
-                or (isinstance(node.expr, astng.CallFunc)
-                    and isinstance(node.expr.func, astng.Name)
-                    and node.expr.func.name == 'super')):
-                self.add_message('W0212', node=node, args=attrname)
 
+            # We are not in a class, no remaining valid case
+            if klass is None:
+                self.add_message('protected-access', node=node, args=attrname)
+                return
+
+            # If the expression begins with a call to super, that's ok.
+            if isinstance(node.expr, astroid.CallFunc) and \
+               isinstance(node.expr.func, astroid.Name) and \
+               node.expr.func.name == 'super':
+                return
+
+            # We are in a class, one remaining valid cases, Klass._attr inside
+            # Klass
+            if not (callee == klass.name or callee in klass.basenames):
+                self.add_message('protected-access', node=node, args=attrname)
 
     def visit_name(self, node):
         """check if the name handle an access to a class member
         if so, register it
         """
         if self._first_attrs and (node.name == self._first_attrs[-1] or
                                   not self._first_attrs[-1]):
             self._meth_could_be_func = False
 
     def _check_accessed_members(self, node, accessed):
         """check that accessed members are defined"""
         # XXX refactor, probably much simpler now that E0201 is in type checker
-        for attr, nodes in accessed.items():
+        for attr, nodes in accessed.iteritems():
             # deactivate "except doesn't do anything", that's expected
             # pylint: disable=W0704
-            # is it a class attribute ?
             try:
+                # is it a class attribute ?
                 node.local_attr(attr)
                 # yes, stop here
                 continue
-            except astng.NotFoundError:
+            except astroid.NotFoundError:
                 pass
             # is it an instance attribute of a parent class ?
             try:
                 node.instance_attr_ancestors(attr).next()
                 # yes, stop here
                 continue
             except StopIteration:
                 pass
             # is it an instance attribute ?
             try:
                 defstmts = node.instance_attr(attr)
-            except astng.NotFoundError:
+            except astroid.NotFoundError:
                 pass
             else:
+                # filter out augment assignment nodes
+                defstmts = [stmt for stmt in defstmts if stmt not in nodes]
+                if not defstmts:
+                    # only augment assignment for this node, no-member should be
+                    # triggered by the typecheck checker
+                    continue
+                # filter defstmts to only pick the first one when there are
+                # several assignments in the same scope
+                scope = defstmts[0].scope()
+                defstmts = [stmt for i, stmt in enumerate(defstmts)
+                            if i == 0 or stmt.scope() is not scope]
+                # if there are still more than one, don't attempt to be smarter
+                # than we can be
                 if len(defstmts) == 1:
                     defstmt = defstmts[0]
                     # check that if the node is accessed in the same method as
                     # it's defined, it's accessed after the initial assignment
                     frame = defstmt.frame()
                     lno = defstmt.fromlineno
                     for _node in nodes:
                         if _node.frame() is frame and _node.fromlineno < lno \
                            and not are_exclusive(_node.statement(), defstmt, ('AttributeError', 'Exception', 'BaseException')):
-                            self.add_message('E0203', node=_node,
-                                             args=(attr, lno))
+                            self.add_message('access-member-before-definition',
+                                             node=_node, args=(attr, lno))
 
     def _check_first_arg_for_type(self, node, metaclass=0):
         """check the name of first argument, expect:
 
         * 'self' for a regular method
-        * 'cls' for a class method
-        * 'mcs' for a metaclass
+        * 'cls' for a class method or a metaclass regular method (actually
+          valid-classmethod-first-arg value)
+        * 'mcs' for a metaclass class method (actually
+          valid-metaclass-classmethod-first-arg)
         * not one of the above for a static method
         """
         # don't care about functions with unknown argument (builtins)
         if node.args.args is None:
             return
         first_arg = node.args.args and node.argnames()[0]
         self._first_attrs.append(first_arg)
         first = self._first_attrs[-1]
         # static method
         if node.type == 'staticmethod':
-            if first_arg in ('self', 'cls', 'mcs'):
-                self.add_message('W0211', args=first, node=node)
+            if (first_arg == 'self' or
+                    first_arg in self.config.valid_classmethod_first_arg or
+                    first_arg in self.config.valid_metaclass_classmethod_first_arg):
+                self.add_message('bad-staticmethod-argument', args=first, node=node)
+                return
             self._first_attrs[-1] = None
         # class / regular method with no args
         elif not node.args.args:
-            self.add_message('E0211', node=node)
-        # metaclass method
+            self.add_message('no-method-argument', node=node)
+        # metaclass
         elif metaclass:
-            if first != 'mcs':
-                self.add_message('C0203', node=node)
-        # class method
-        elif node.type == 'classmethod':
-            if first not in self.config.valid_classmethod_first_arg:
-                if len(self.config.valid_classmethod_first_arg) == 1:
-                    valid = repr(self.config.valid_classmethod_first_arg[0])
-                else:
-                    valid = ', '.join(
-                      repr(v)
-                      for v in self.config.valid_classmethod_first_arg[:-1])
-                    valid = '%s or %r' % (
-                        valid, self.config.valid_classmethod_first_arg[-1])
-                self.add_message('C0202', args=valid, node=node)
-        # regular method without self as argument
-        elif first != 'self':
-            self.add_message('E0213', node=node)
+            # metaclass __new__ or classmethod
+            if node.type == 'classmethod':
+                self._check_first_arg_config(
+                    first,
+                    self.config.valid_metaclass_classmethod_first_arg, node,
+                    'bad-mcs-classmethod-argument', node.name)
+            # metaclass regular method
+            else:
+                self._check_first_arg_config(
+                    first,
+                    self.config.valid_classmethod_first_arg, node, 'bad-mcs-method-argument',
+                    node.name)
+        # regular class
+        else:
+            # class method
+            if node.type == 'classmethod':
+                self._check_first_arg_config(
+                    first,
+                    self.config.valid_classmethod_first_arg, node, 'bad-classmethod-argument',
+                    node.name)
+            # regular method without self as argument
+            elif first != 'self':
+                self.add_message('no-self-argument', node=node)
+
+    def _check_first_arg_config(self, first, config, node, message,
+                                method_name):
+        if first not in config:
+            if len(config) == 1:
+                valid = repr(config[0])
+            else:
+                valid = ', '.join(repr(v) for v in config[:-1])
+                valid = '%s or %r' % (valid, config[-1])
+            self.add_message(message, args=(method_name, valid), node=node)
 
     def _check_bases_classes(self, node):
         """check that the given class node implements abstract methods from
         base classes
         """
         # check if this class abstract
         if class_is_abstract(node):
             return
         for method in node.methods():
             owner = method.parent.frame()
             if owner is node:
                 continue
             # owner is not this class, it must be a parent class
             # check that the ancestor's method is not abstract
+            if method.name in node.locals:
+                # it is redefined as an attribute or with a descriptor
+                continue
             if method.is_abstract(pass_is_abstract=False):
-                self.add_message('W0223', node=node,
+                self.add_message('abstract-method', node=node,
                                  args=(method.name, owner.name))
 
     def _check_interfaces(self, node):
         """check that the given class node really implements declared
         interfaces
         """
         e0221_hack = [False]
         def iface_handler(obj):
             """filter interface objects, it should be classes"""
-            if not isinstance(obj, astng.Class):
+            if not isinstance(obj, astroid.Class):
                 e0221_hack[0] = True
-                self.add_message('E0221', node=node,
+                self.add_message('interface-is-not-class', node=node,
                                  args=(obj.as_string(),))
                 return False
             return True
         ignore_iface_methods = self.config.ignore_iface_methods
         try:
             for iface in node.interfaces(handler_func=iface_handler):
                 for imethod in iface.methods():
                     name = imethod.name
                     if name.startswith('_') or name in ignore_iface_methods:
                         # don't check method beginning with an underscore,
                         # usually belonging to the interface implementation
                         continue
-                    # get class method astng
+                    # get class method astroid
                     try:
                         method = node_method(node, name)
-                    except astng.NotFoundError:
-                        self.add_message('E0222', args=(name, iface.name),
+                    except astroid.NotFoundError:
+                        self.add_message('missing-interface-method', args=(name, iface.name),
                                          node=node)
                         continue
                     # ignore inherited methods
                     if method.parent.frame() is not node:
                         continue
                     # check signature
                     self._check_signature(method, imethod,
-                                         '%s interface' % iface.name)
-        except astng.InferenceError:
+                                          '%s interface' % iface.name)
+        except astroid.InferenceError:
             if e0221_hack[0]:
                 return
             implements = Instance(node).getattr('__implements__')[0]
             assignment = implements.parent
-            assert isinstance(assignment, astng.Assign)
+            assert isinstance(assignment, astroid.Assign)
             # assignment.expr can be a Name or a Tuple or whatever.
             # Use as_string() for the message
             # FIXME: in case of multiple interfaces, find which one could not
             #        be resolved
-            self.add_message('F0220', node=implements,
+            self.add_message('unresolved-interface', node=implements,
                              args=(node.name, assignment.value.as_string()))
 
     def _check_init(self, node):
         """check that the __init__ method call super or ancestors'__init__
         method
         """
-        if not set(('W0231', 'W0233')) & self.active_msgs:
+        if (not self.linter.is_message_enabled('super-init-not-called') and
+                not self.linter.is_message_enabled('non-parent-init-called')):
             return
         klass_node = node.parent.frame()
         to_call = _ancestors_to_call(klass_node)
         not_called_yet = dict(to_call)
-        for stmt in node.nodes_of_class(astng.CallFunc):
+        for stmt in node.nodes_of_class(astroid.CallFunc):
             expr = stmt.func
-            if not isinstance(expr, astng.Getattr) \
+            if not isinstance(expr, astroid.Getattr) \
                    or expr.attrname != '__init__':
                 continue
             # skip the test if using super
-            if isinstance(expr.expr, astng.CallFunc) and \
-               isinstance(expr.expr.func, astng.Name) and \
+            if isinstance(expr.expr, astroid.CallFunc) and \
+                   isinstance(expr.expr.func, astroid.Name) and \
                expr.expr.func.name == 'super':
                 return
             try:
                 klass = expr.expr.infer().next()
                 if klass is YES:
                     continue
                 try:
                     del not_called_yet[klass]
                 except KeyError:
                     if klass not in to_call:
-                        self.add_message('W0233', node=expr, args=klass.name)
-            except astng.InferenceError:
+                        self.add_message('non-parent-init-called', node=expr, args=klass.name)
+            except astroid.InferenceError:
                 continue
-        for klass in not_called_yet.keys():
-            if klass.name == 'object':
+        for klass, method in not_called_yet.iteritems():
+            if klass.name == 'object' or method.parent.name == 'object':
                 continue
-            self.add_message('W0231', args=klass.name, node=node)
+            self.add_message('super-init-not-called', args=klass.name, node=node)
 
     def _check_signature(self, method1, refmethod, class_type):
         """check that the signature of the two given methods match
 
         class_type is in 'class', 'interface'
         """
-        if not (isinstance(method1, astng.Function)
-                and isinstance(refmethod, astng.Function)):
-            self.add_message('F0202', args=(method1, refmethod), node=method1)
+        if not (isinstance(method1, astroid.Function)
+                and isinstance(refmethod, astroid.Function)):
+            self.add_message('method-check-failed', args=(method1, refmethod), node=method1)
             return
         # don't care about functions with unknown argument (builtins)
         if method1.args.args is None or refmethod.args.args is None:
             return
         # if we use *args, **kwargs, skip the below checks
         if method1.args.vararg or method1.args.kwarg:
             return
+        if is_attr_private(method1.name):
+            return
         if len(method1.args.args) != len(refmethod.args.args):
-            self.add_message('W0221', args=class_type, node=method1)
+            self.add_message('arguments-differ', args=class_type, node=method1)
         elif len(method1.args.defaults) < len(refmethod.args.defaults):
-            self.add_message('W0222', args=class_type, node=method1)
+            self.add_message('signature-differs', args=class_type, node=method1)
 
+    def is_first_attr(self, node):
+        """Check that attribute lookup name use first attribute variable name
+        (self for method, cls for classmethod and mcs for metaclass).
+        """
+        return self._first_attrs and isinstance(node.expr, astroid.Name) and \
+                   node.expr.name == self._first_attrs[-1]
 
 def _ancestors_to_call(klass_node, method='__init__'):
     """return a dictionary where keys are the list of base classes providing
     the queried method, and so that should/may be called from the method node
     """
     to_call = {}
     for base_node in klass_node.ancestors(recurs=False):
         try:
-            base_node.local_attr(method)
-            to_call[base_node] = 1
-        except astng.NotFoundError:
+            to_call[base_node] = base_node.igetattr(method).next()
+        except astroid.InferenceError:
             continue
     return to_call
 
 
 def node_method(node, method_name):
-    """get astng for <method_name> on the given class node, ensuring it
+    """get astroid for <method_name> on the given class node, ensuring it
     is a Function node
     """
     for n in node.local_attr(method_name):
-        if isinstance(n, astng.Function):
+        if isinstance(n, astroid.Function):
             return n
-    raise astng.NotFoundError(method_name)
+    raise astroid.NotFoundError(method_name)
 
 def register(linter):
     """required method to auto register this checker """
     linter.register_checker(ClassChecker(linter))