| # Copyright (c) 2003-2007 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. |
| """exceptions handling (raising, catching, exceptions classes) checker |
| """ |
| import sys |
| |
| from logilab.common.compat import builtins |
| BUILTINS_NAME = builtins.__name__ |
| from logilab import astng |
| from logilab.astng import YES, Instance, unpack_infer |
| |
| from pylint.checkers import BaseChecker |
| from pylint.checkers.utils import is_empty, is_raising |
| from pylint.interfaces import IASTNGChecker |
| |
| |
| OVERGENERAL_EXCEPTIONS = ('Exception',) |
| |
| MSGS = { |
| 'E0701': ( |
| 'Bad except clauses order (%s)', |
| 'Used when except clauses are not in the correct order (from the \ |
| more specific to the more generic). If you don\'t fix the order, \ |
| some exceptions may not be catched by the most specific handler.'), |
| 'E0702': ('Raising %s while only classes, instances or string are allowed', |
| 'Used when something which is neither a class, an instance or a \ |
| string is raised (i.e. a `TypeError` will be raised).'), |
| 'E0710': ('Raising a new style class which doesn\'t inherit from BaseException', |
| 'Used when a new style class which doesn\'t inherit from \ |
| BaseException is raised.'), |
| 'E0711': ('NotImplemented raised - should raise NotImplementedError', |
| 'Used when NotImplemented is raised instead of \ |
| NotImplementedError'), |
| |
| 'W0701': ('Raising a string exception', |
| 'Used when a string exception is raised.'), |
| 'W0702': ('No exception type(s) specified', |
| 'Used when an except clause doesn\'t specify exceptions type to \ |
| catch.'), |
| 'W0703': ('Catching too general exception %s', |
| 'Used when an except catches a too general exception, \ |
| possibly burying unrelated errors.'), |
| 'W0704': ('Except doesn\'t do anything', |
| 'Used when an except clause does nothing but "pass" and there is\ |
| no "else" clause.'), |
| 'W0710': ('Exception doesn\'t inherit from standard "Exception" class', |
| 'Used when a custom exception class is raised but doesn\'t \ |
| inherit from the builtin "Exception" class.'), |
| } |
| |
| |
| if sys.version_info < (3, 0): |
| EXCEPTIONS_MODULE = "exceptions" |
| else: |
| EXCEPTIONS_MODULE = "builtins" |
| |
| class ExceptionsChecker(BaseChecker): |
| """checks for |
| * excepts without exception filter |
| * type of raise argument : string, Exceptions, other values |
| """ |
| |
| __implements__ = IASTNGChecker |
| |
| name = 'exceptions' |
| msgs = MSGS |
| priority = -4 |
| options = (('overgeneral-exceptions', |
| {'default' : OVERGENERAL_EXCEPTIONS, |
| 'type' :'csv', 'metavar' : '<comma-separated class names>', |
| 'help' : 'Exceptions that will emit a warning ' |
| 'when being caught. Defaults to "%s"' % ( |
| ', '.join(OVERGENERAL_EXCEPTIONS),)} |
| ), |
| ) |
| |
| def visit_raise(self, node): |
| """visit raise possibly inferring value""" |
| # ignore empty raise |
| if node.exc is None: |
| return |
| expr = node.exc |
| if self._check_raise_value(node, expr): |
| return |
| else: |
| try: |
| value = unpack_infer(expr).next() |
| except astng.InferenceError: |
| return |
| self._check_raise_value(node, value) |
| |
| def _check_raise_value(self, node, expr): |
| """check for bad values, string exception and class inheritance |
| """ |
| value_found = True |
| if isinstance(expr, astng.Const): |
| value = expr.value |
| if isinstance(value, str): |
| self.add_message('W0701', node=node) |
| else: |
| self.add_message('E0702', node=node, |
| args=value.__class__.__name__) |
| elif (isinstance(expr, astng.Name) and \ |
| expr.name in ('None', 'True', 'False')) or \ |
| isinstance(expr, (astng.List, astng.Dict, astng.Tuple, |
| astng.Module, astng.Function)): |
| self.add_message('E0702', node=node, args=expr.name) |
| elif ( (isinstance(expr, astng.Name) and expr.name == 'NotImplemented') |
| or (isinstance(expr, astng.CallFunc) and |
| isinstance(expr.func, astng.Name) and |
| expr.func.name == 'NotImplemented') ): |
| self.add_message('E0711', node=node) |
| elif isinstance(expr, astng.BinOp) and expr.op == '%': |
| self.add_message('W0701', node=node) |
| elif isinstance(expr, (Instance, astng.Class)): |
| if isinstance(expr, Instance): |
| expr = expr._proxied |
| if (isinstance(expr, astng.Class) and |
| not inherit_from_std_ex(expr) and |
| expr.root().name != BUILTINS_NAME): |
| if expr.newstyle: |
| self.add_message('E0710', node=node) |
| else: |
| self.add_message('W0710', node=node) |
| else: |
| value_found = False |
| else: |
| value_found = False |
| return value_found |
| |
| |
| def visit_tryexcept(self, node): |
| """check for empty except""" |
| exceptions_classes = [] |
| nb_handlers = len(node.handlers) |
| for index, handler in enumerate(node.handlers): |
| # single except doing nothing but "pass" without else clause |
| if nb_handlers == 1 and is_empty(handler.body) and not node.orelse: |
| self.add_message('W0704', node=handler.type or handler.body[0]) |
| if handler.type is None: |
| if nb_handlers == 1 and not is_raising(handler.body): |
| self.add_message('W0702', node=handler) |
| # check if a "except:" is followed by some other |
| # except |
| elif index < (nb_handlers - 1): |
| msg = 'empty except clause should always appear last' |
| self.add_message('E0701', node=node, args=msg) |
| else: |
| try: |
| excs = list(unpack_infer(handler.type)) |
| except astng.InferenceError: |
| continue |
| for exc in excs: |
| # XXX skip other non class nodes |
| if exc is YES or not isinstance(exc, astng.Class): |
| continue |
| exc_ancestors = [anc for anc in exc.ancestors() |
| if isinstance(anc, astng.Class)] |
| for previous_exc in exceptions_classes: |
| if previous_exc in exc_ancestors: |
| msg = '%s is an ancestor class of %s' % ( |
| previous_exc.name, exc.name) |
| self.add_message('E0701', node=handler.type, args=msg) |
| if (exc.name in self.config.overgeneral_exceptions |
| and exc.root().name == EXCEPTIONS_MODULE |
| and nb_handlers == 1 and not is_raising(handler.body)): |
| self.add_message('W0703', args=exc.name, node=handler.type) |
| exceptions_classes += excs |
| |
| |
| def inherit_from_std_ex(node): |
| """return true if the given class node is subclass of |
| exceptions.Exception |
| """ |
| if node.name in ('Exception', 'BaseException') \ |
| and node.root().name == EXCEPTIONS_MODULE: |
| return True |
| for parent in node.ancestors(recurs=False): |
| if inherit_from_std_ex(parent): |
| return True |
| return False |
| |
| def register(linter): |
| """required method to auto register this checker""" |
| linter.register_checker(ExceptionsChecker(linter)) |
