forget the past.

forget the past.

1 files changed, 167 insertions, 0 deletions

diff --git a/checkers/exceptions.py b/checkers/exceptions.py
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+# 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.
+""" Copyright (c) 2003-2005 LOGILAB S.A. (Paris, FRANCE).
+ http://www.logilab.fr/ -- mailto:contact@logilab.fr
+
+exceptions checkers for Python code
+"""
+
+__revision__ = '$Id: exceptions.py,v 1.27 2006-03-08 15:53:42 syt Exp $'
+
+from logilab.common.compat import enumerate
+from logilab import astng
+from logilab.astng.inference import unpack_infer
+
+from pylint.checkers import BaseChecker
+from pylint.checkers.utils import is_empty
+from pylint.interfaces import IASTNGChecker
+
+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).'),
+    
+    'W0701': ('Raising a string exception',
+              'Used when a string exception is raised.'),
+    'W0702': ('No exception\'s type specified',
+              'Used when an except clause doesn\'t specify exceptions type to \
+              catch.'),
+    'W0703': ('Catch "Exception"',
+              'Used when an except catch Exception instances.'),
+    'W0704': ('Except doesn\'t do anything',
+              'Used when an except clause does nothing but "pass" and there is\
+              no "else" clause.'),
+    'W0706': (
+    'Identifier %s used to raise an exception is assigned to %s',
+    'Used when a variable used to raise an exception is initially \
+    assigned to a value which can\'t be used as an exception.'),
+    }
+
+def is_raising(stmt):
+    """return true if the given statement node raise an exception
+    """
+    for node in stmt.nodes:
+        if isinstance(node, astng.Raise):
+            return 1
+    return 0
+    
+class ExceptionsChecker(BaseChecker):
+    """checks for                                                              
+    * excepts without exception filter                                         
+    * string exceptions                                                        
+    """
+    
+    __implements__ = IASTNGChecker
+
+    name = 'exceptions'
+    msgs = MSGS
+    priority = -4
+    options = ()
+
+    def visit_raise(self, node):
+        """check for string exception
+        """
+        # ignore empty raise
+        if node.expr1 is None:
+            return
+        expr = node.expr1
+        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'):                
+            self.add_message('E0702', node=node, args=expr.name)
+        elif isinstance(expr, astng.Mod):
+            self.add_message('W0701', node=node)
+        else:
+            try:
+                value = unpack_infer(expr).next()
+            except astng.InferenceError:
+                return
+            if value is astng.YES:
+                return
+            # must to be carefull since Const, Dict, .. inherit from
+            # Instance now
+            if isinstance(value, (astng.Class, astng.Module)):
+                return
+            if isinstance(value, astng.Instance) and \
+               isinstance(value._proxied, astng.Class):
+                return
+            if isinstance(value, astng.Const) and \
+               (value.value is None or 
+                value.value is True or value.value is False):
+                # this Const has been generated by resolve
+                # since None, True and False are represented by Name
+                # nodes in the ast, and so this const node doesn't
+                # have the necessary parent, lineno and so on attributes
+                assinfo = value.as_string()
+            else:
+                assinfo = '%s line %s' % (value.as_string(),
+                                          value.source_line())
+            self.add_message('W0706', node=node,
+                             args=(expr.as_string(), assinfo))
+            
+    def visit_tryexcept(self, node):
+        """check for empty except
+        """
+        exceptions_classes = []
+        nb_handlers = len(node.handlers)
+        for index, handler  in enumerate(node.handlers):
+            exc_type = handler[0]
+            stmt = handler[2]
+            # single except doing nothing but "pass" without else clause
+            if nb_handlers == 1 and is_empty(stmt) and not node.else_:
+                self.add_message('W0704', node=exc_type)
+            if exc_type is None:
+                if nb_handlers == 1 and not is_raising(stmt):
+                    self.add_message('W0702', node=stmt.nodes[0])
+                # check if a "except:" is followed by some other
+                # except
+                elif index < (nb_handlers - 1):
+                    msg = 'empty except clause should always appears last'
+                    self.add_message('E0701', node=node, args=msg)
+            else:
+                try:
+                    excs = list(unpack_infer(exc_type))
+                except astng.InferenceError:
+                    continue
+                for exc in excs:
+                    if exc is astng.YES:
+                        continue
+                    if not isinstance(exc, astng.Class):
+                        continue # XXX
+                    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=exc_type, args=msg)
+                    if (exc.name == 'Exception'
+                        and exc.root().name == 'exceptions'
+                        and nb_handlers == 1 and not is_raising(stmt)):
+                        self.add_message('W0703', node=exc_type)
+                exceptions_classes += excs
+        
+def register(linter):
+    """required method to auto register this checker"""
+    linter.register_checker(ExceptionsChecker(linter))