# Copyright (c) 2006, 2008-2011, 2013-2014 LOGILAB S.A. (Paris, FRANCE) # Copyright (c) 2012-2014 Google, Inc. # Copyright (c) 2013-2017 Claudiu Popa # Copyright (c) 2014 Michal Nowikowski # Copyright (c) 2014 Brett Cannon # Copyright (c) 2014 Arun Persaud # Copyright (c) 2015 Ionel Cristian Maries # Copyright (c) 2016 Alexander Todorov # Copyright (c) 2016 Jakub Wilk # Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html # For details: https://github.com/PyCQA/pylint/blob/master/COPYING """check for new / old style related problems """ import sys import astroid from pylint.interfaces import IAstroidChecker, INFERENCE, INFERENCE_FAILURE, HIGH from pylint.checkers import BaseChecker from pylint.checkers.utils import ( check_messages, node_frame_class, has_known_bases ) MSGS = { 'E1001': ('Use of __slots__ on an old style class', 'slots-on-old-class', 'Used when an old style class uses the __slots__ attribute.', {'maxversion': (3, 0)}), 'E1002': ('Use of super on an old style class', 'super-on-old-class', 'Used when an old style class uses the super builtin.', {'maxversion': (3, 0)}), 'E1003': ('Bad first argument %r given to super()', 'bad-super-call', 'Used when another argument than the current class is given as \ first argument of the super builtin.'), 'E1004': ('Missing argument to super()', 'missing-super-argument', 'Used when the super builtin didn\'t receive an \ argument.', {'maxversion': (3, 0)}), 'W1001': ('Use of "property" on an old style class', 'property-on-old-class', 'Used when Pylint detect the use of the builtin "property" \ on an old style class while this is relying on new style \ classes features.', {'maxversion': (3, 0)}), 'C1001': ('Old-style class defined.', 'old-style-class', 'Used when a class is defined that does not inherit from another ' 'class and does not inherit explicitly from "object".', {'maxversion': (3, 0)}) } class NewStyleConflictChecker(BaseChecker): """checks for usage of new style capabilities on old style classes and other new/old styles conflicts problems * use of property, __slots__, super * "super" usage """ __implements__ = (IAstroidChecker,) # configuration section name name = 'newstyle' # messages msgs = MSGS priority = -2 # configuration options options = () @check_messages('slots-on-old-class', 'old-style-class') def visit_classdef(self, node): """ Check __slots__ in old style classes and old style class definition. """ if '__slots__' in node and not node.newstyle: confidence = (INFERENCE if has_known_bases(node) else INFERENCE_FAILURE) self.add_message('slots-on-old-class', node=node, confidence=confidence) # The node type could be class, exception, metaclass, or # interface. Presumably, the non-class-type nodes would always # have an explicit base class anyway. if not node.bases and node.type == 'class' and not node.metaclass(): # We use confidence HIGH here because this message should only ever # be emitted for classes at the root of the inheritance hierarchyself. self.add_message('old-style-class', node=node, confidence=HIGH) @check_messages('property-on-old-class') def visit_call(self, node): """check property usage""" parent = node.parent.frame() if (isinstance(parent, astroid.ClassDef) and not parent.newstyle and isinstance(node.func, astroid.Name)): confidence = (INFERENCE if has_known_bases(parent) else INFERENCE_FAILURE) name = node.func.name if name == 'property': self.add_message('property-on-old-class', node=node, confidence=confidence) @check_messages('super-on-old-class', 'bad-super-call', 'missing-super-argument') def visit_functiondef(self, node): """check use of super""" # ignore actual functions or method within a new style class if not node.is_method(): return klass = node.parent.frame() for stmt in node.nodes_of_class(astroid.Call): if node_frame_class(stmt) != node_frame_class(node): # Don't look down in other scopes. continue expr = stmt.func if not isinstance(expr, astroid.Attribute): continue call = expr.expr # skip the test if using super if not (isinstance(call, astroid.Call) and isinstance(call.func, astroid.Name) and call.func.name == 'super'): continue if not klass.newstyle and has_known_bases(klass): # super should not be used on an old style class self.add_message('super-on-old-class', node=node) else: # super first arg should be the class if not call.args: if sys.version_info[0] == 3: # unless Python 3 continue else: self.add_message('missing-super-argument', node=call) continue # calling super(type(self), self) can lead to recursion loop # in derived classes arg0 = call.args[0] if isinstance(arg0, astroid.Call) and \ isinstance(arg0.func, astroid.Name) and \ arg0.func.name == 'type': self.add_message('bad-super-call', node=call, args=('type', )) continue # calling super(self.__class__, self) can lead to recursion loop # in derived classes if len(call.args) >= 2 and \ isinstance(call.args[1], astroid.Name) and \ call.args[1].name == 'self' and \ isinstance(arg0, astroid.Attribute) and \ arg0.attrname == '__class__': self.add_message('bad-super-call', node=call, args=('self.__class__', )) continue try: supcls = call.args and next(call.args[0].infer(), None) except astroid.InferenceError: continue if klass is not supcls: name = None # if supcls is not YES, then supcls was infered # and use its name. Otherwise, try to look # for call.args[0].name if supcls: name = supcls.name elif call.args and hasattr(call.args[0], 'name'): name = call.args[0].name if name: self.add_message('bad-super-call', node=call, args=(name, )) visit_asyncfunctiondef = visit_functiondef def register(linter): """required method to auto register this checker """ linter.register_checker(NewStyleConflictChecker(linter))