Add pylint to depot_tools.

third_party/pylint/checkers/base.py

Index: third_party/pylint/checkers/base.py
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+# Copyright (c) 2003-2010 LOGILAB S.A. (Paris, FRANCE).
+# 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.
+"""basic checker for Python code"""
+
+
+from logilab import astng
+from logilab.common.ureports import Table
+from logilab.astng import are_exclusive
+
+from pylint.interfaces import IASTNGChecker
+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
+
+
+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}$')
+# do not require a doc string on system methods
+NO_REQUIRED_DOC_RGX = re.compile('__.*__')
+
+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)):
+            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 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:
+            total = stats[node_type]
+        except KeyError:
+            raise EmptyReport()
+        nice_stats[node_type] = {}
+        if total != 0:
+            try:
+                documented = total - stats['undocumented_'+node_type]
+                percent = (documented * 100.) / total
+                nice_stats[node_type]['percent_documented'] = '%.2f' % percent
+            except KeyError:
+                nice_stats[node_type]['percent_documented'] = 'NC'
+            try:
+                percent = (stats['badname_'+node_type] * 100.) / total
+                nice_stats[node_type]['percent_badname'] = '%.2f' % percent
+            except KeyError:
+                nice_stats[node_type]['percent_badname'] = 'NC'
+    lines = ('type', 'number', 'old number', 'difference',
+             '%documented', '%badname')
+    for node_type in ('module', 'class', 'method', 'function'):
+        new = stats[node_type]
+        old = old_stats.get(node_type, None)
+        if old is not None:
+            diff_str = diff_string(old, new)
+        else:
+            old, diff_str = 'NC', 'NC'
+        lines += (node_type, str(new), str(old), diff_str,
+                  nice_stats[node_type].get('percent_documented', '0'),
+                  nice_stats[node_type].get('percent_badname', '0'))
+    sect.append(Table(children=lines, cols=6, rheaders=1))
+
+def redefined_by_decorator(node):
+    """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):
+                return True
+    return False
+
+class _BasicChecker(BaseChecker):
+    __implements__ = IASTNGChecker
+    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.'),
+
+    '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')
+    def visit_class(self, node):
+        self._check_redefinition('class', node)
+
+    @check_messages('E0100', 'E0101', 'E0102', 'E0106')
+    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))
+        if node.is_method() and node.name == '__init__':
+            if node.is_generator():
+                self.add_message('E0100', 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)
+        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)
+
+    @check_messages('E0104')
+    def visit_return(self, node):
+        if not isinstance(node.frame(), astng.Function):
+            self.add_message('E0104', node=node)
+
+    @check_messages('E0105')
+    def visit_yield(self, node):
+        if not isinstance(node.frame(), astng.Function):
+            self.add_message('E0105', node=node)
+
+    @check_messages('E0103')
+    def visit_continue(self, node):
+        self._check_in_loop(node, 'continue')
+
+    @check_messages('E0103')
+    def visit_break(self, node):
+        self._check_in_loop(node, 'break')
+
+    @check_messages('E0107')
+    def visit_unaryop(self, node):
+        """check use of the non-existent ++ adn -- 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)
+
+    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)):
+                break
+            _node = _node.parent
+        else:
+            self.add_message('E0103', 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,
+                             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
+
+    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 !'),
+
+    '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
+              'Used when an attribute required for modules is missing.'),
+
+    }
+
+    options = (('required-attributes',
+                {'default' : (), 'type' : 'csv',
+                 'metavar' : '<attributes>',
+                 'help' : 'Required attributes for module, separated by a '
+                          'comma'}
+                ),
+               ('bad-functions',
+                {'default' : ('map', 'filter', 'apply', 'input'),
+                 '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), )
+
+    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)
+
+    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)
+
+    def visit_class(self, node):
+        """check module name, docstring and redefinition
+        increment branch counter
+        """
+        self.stats['class'] += 1
+
+    @check_messages('W0104', 'W0105')
+    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):
+            # treat string statement in a separated message
+            self.add_message('W0105', 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])):
+            return
+        if any(expr.nodes_of_class(astng.CallFunc)):
+            self.add_message('W0106', node=node, args=expr.as_string())
+        else:
+            self.add_message('W0104', node=node)
+
+    @check_messages('W0108')
+    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):
+            # 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 ?
+        # *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):
+                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):
+                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):
+                return
+            if node.args.args[i].name != call.args[i].name:
+                return
+        self.add_message('W0108', line=node.fromlineno, node=node)
+
+    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:
+                continue
+            if isinstance(value, (astng.Dict, astng.List)):
+                if value is default:
+                    msg = default.as_string()
+                else:
+                    msg = '%s (%s)' % (default.as_string(), value.as_string())
+                self.add_message('W0102', node=node, args=(msg,))
+
+    @check_messages('W0101', 'W0150')
+    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,))
+
+    @check_messages('W0101')
+    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')
+    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,))
+
+    @check_messages('W0101')
+    def visit_raise(self, node):
+        """check is the node has a right sibling (if so, that's some unreachable
+        code)
+        """
+        self._check_unreachable(node)
+
+    @check_messages('W0122')
+    def visit_exec(self, node):
+        """just print a warning on exec statements"""
+        self.add_message('W0122', node=node)
+
+    @check_messages('W0141', 'W0142')
+    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):
+            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 in self.config.bad_functions:
+                    self.add_message('W0141', node=node, args=name)
+        if node.starargs or node.kwargs:
+            scope = node.scope()
+            if isinstance(scope, astng.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)
+
+    @check_messages('W0199')
+    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)
+
+    @check_messages('W0109')
+    def visit_dict(self, node):
+        """check duplicate key in dictionary"""
+        keys = set()
+        for k, v in node.items:
+            if isinstance(k, astng.Const):
+                key = k.value
+                if key in keys:
+                    self.add_message('W0109', 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)
+
+    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)
+                return
+            _node = _parent
+            _parent = _node.parent
+
+
+
+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...).'),
+
+    }
+    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',
+                {'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'}
+                ),
+               )
+
+    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)
+
+    @check_messages('C0102', 'C0103')
+    def visit_module(self, node):
+        self._check_name('module', node.name.split('.')[-1], node)
+
+    @check_messages('C0102', 'C0103')
+    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])
+
+    @check_messages('C0102', 'C0103')
+    def visit_function(self, node):
+        self._check_name(node.is_method() and 'method' or 'function',
+                         node.name, node)
+        # check arguments name
+        args = node.args.args
+        if args is not None:
+            self._recursive_check_names(args, node)
+
+    @check_messages('C0102', 'C0103')
+    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)):
+            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):
+                self._check_name('variable', node.name, node)
+        elif isinstance(frame, astng.Function):
+            # global introduced variable aren't in the function locals
+            if node.name in frame:
+                self._check_name('variable', 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):
+                self._check_name('argument', arg.name, node)
+            else:
+                self._recursive_check_names(arg.elts, node)
+
+    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)
+            return
+        regexp = getattr(self.config, node_type + '_rgx')
+        if regexp.match(name) is None:
+            self.add_message('C0103', node=node, args=(name, regexp.pattern))
+            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 ;).'),
+    }
+    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'}
+                ),
+               )
+
+    def open(self):
+        self.stats = self.linter.add_stats(undocumented_module=0,
+                                           undocumented_function=0,
+                                           undocumented_method=0,
+                                           undocumented_class=0)
+
+    def visit_module(self, node):
+        self._check_docstring('module', node)
+
+    def visit_class(self, node):
+        if self.config.no_docstring_rgx.match(node.name) is None:
+            self._check_docstring('class', node)
+
+    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):
+                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):
+                        overridden = True
+                        break
+                if not overridden:
+                    self._check_docstring(ftype, node)
+            else:
+                self._check_docstring(ftype, node)
+
+    def _check_docstring(self, node_type, node):
+        """check the node has a non empty docstring"""
+        docstring = node.doc
+        if docstring is None:
+            self.stats['undocumented_'+node_type] += 1
+            self.add_message('C0111', node=node)
+        elif not docstring.strip():
+            self.stats['undocumented_'+node_type] += 1
+            self.add_message('C0112', node=node)
+
+
+class PassChecker(_BasicChecker):
+    """check is the pass statement is really necessary"""
+    msgs = {'W0107': ('Unnecessary pass statement',
+                      'Used when a "pass" statement that can be avoided is '
+                      'encountered.)'),
+            }
+
+    def visit_pass(self, node):
+        if len(node.parent.child_sequence(node)) > 1:
+            self.add_message('W0107', 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))