Add pylint to depot_tools.

third_party/pylint/checkers/classes.py

Index: third_party/pylint/checkers/classes.py
diff --git a/third_party/pylint/checkers/classes.py b/third_party/pylint/checkers/classes.py
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+# Copyright (c) 2003-2011 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.
+"""classes checker for Python code
+"""
+from __future__ import generators
+
+from logilab import astng
+from logilab.astng import YES, Instance, are_exclusive
+
+from pylint.interfaces import IASTNGChecker
+from pylint.checkers import BaseChecker
+from pylint.checkers.utils import PYMETHODS, overrides_a_method, check_messages
+
+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)',
+              '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',
+              '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',
+              'Used when an instance member is accessed before it\'s actually\
+              assigned.'),
+    'W0201': ('Attribute %r 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
+              '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',
+              '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',
+              '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.'),
+
+    'W0211': ('Static method with %r as first argument',
+              'Used when a static method has "self" or "cls" as first argument.'
+              ),
+    'R0201': ('Method could be a function',
+              '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',
+              'Used when a class claims to implement an interface which is not \
+              a class.'),
+    'E0222': ('Missing method %r from %s interface',
+              'Used when a method declared in an interface is missing from a \
+              class implementing this interface'),
+    'W0221': ('Arguments number differs from %s method',
+              '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',
+              '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',
+              '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
+              'Used when a PyLint as failed to find interfaces implemented by \
+               a class'),
+
+
+    'W0231': ('__init__ method from base class %r is 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',
+              'Used when a class has no __init__ method, neither its parent \
+              classes.'),
+    'W0233': ('__init__ method from a non direct base class %r is called',
+              'Used when an __init__ method is called on a class which is not \
+              in the direct ancestors for the analysed class.'),
+
+    }
+
+
+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,)
+
+    # 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'),
+                 '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.'}
+                ),
+
+               )
+
+    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)
+
+    @check_messages('E0203', 'W0201')
+    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:
+            return
+        defining_methods = self.config.defining_attr_methods
+        for attr, nodes in cnode.instance_attrs.items():
+            nodes = [n for n in nodes if not
+                    isinstance(n.statement(), (astng.Delete, astng.AugAssign))]
+            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)
+
+    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
+            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
+                continue
+            if not isinstance(meth_node, astng.Function):
+                continue
+            self._check_signature(node, meth_node, 'overridden')
+            break
+        # check if the method overload 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:
+            pass
+
+    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:
+                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)
+
+    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]:
+            self._accessed[-1].setdefault(attrname, []).append(node)
+            return
+        if 'W0212' not in self.active_msgs:
+            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()
+            # 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)
+
+
+    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():
+            # deactivate "except doesn't do anything", that's expected
+            # pylint: disable=W0704
+            # is it a class attribute ?
+            try:
+                node.local_attr(attr)
+                # yes, stop here
+                continue
+            except astng.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:
+                pass
+            else:
+                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))
+
+    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
+        * 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)
+            self._first_attrs[-1] = None
+        # class / regular method with no args
+        elif not node.args.args:
+            self.add_message('E0211', node=node)
+        # metaclass method
+        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)
+
+    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.is_abstract(pass_is_abstract=False):
+                self.add_message('W0223', 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):
+                e0221_hack[0] = True
+                self.add_message('E0221', 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
+                    try:
+                        method = node_method(node, name)
+                    except astng.NotFoundError:
+                        self.add_message('E0222', 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:
+            if e0221_hack[0]:
+                return
+            implements = Instance(node).getattr('__implements__')[0]
+            assignment = implements.parent
+            assert isinstance(assignment, astng.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,
+                             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:
+            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):
+            expr = stmt.func
+            if not isinstance(expr, astng.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 \
+               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:
+                continue
+        for klass in not_called_yet.keys():
+            if klass.name == 'object':
+                continue
+            self.add_message('W0231', 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)
+            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 len(method1.args.args) != len(refmethod.args.args):
+            self.add_message('W0221', args=class_type, node=method1)
+        elif len(method1.args.defaults) < len(refmethod.args.defaults):
+            self.add_message('W0222', args=class_type, node=method1)
+
+
+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:
+            continue
+    return to_call
+
+
+def node_method(node, method_name):
+    """get astng 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):
+            return n
+    raise astng.NotFoundError(method_name)
+
+def register(linter):
+    """required method to auto register this checker """
+    linter.register_checker(ClassChecker(linter))